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    • 专利摘要:
    The present invention relates to a method for improving a blade as well as to such an improved blade and to an advancing propeller comprising said improved blades. The radius of an initial leading edge circle (15, 25) of each airfoil (10) of said blade is increased and its leading edge (5) is displaced by a half-intrados profile ( 21) to a half extrados profile (11), thereby changing the aerodynamic profile (10) of each cross section of said blade and the camber of each airfoil (10). Consequently, a negative incidence of stalling of said blade is increased, in absolute value, thus making it possible to increase the aerodynamic performance of said blade under a negative incidence compared to an unmodified blade, without significant degradation of its aerodynamic performance under a positive impact.
    公开号:FR3077803A1
    申请号:FR1870167
    申请日:2018-02-15
    公开日:2019-08-16
    发明作者:Raphael FUKARI；Paul Eglin
    申请人:Airbus Helicopters SAS；
    IPC主号:
    专利说明:

    Method of improving a blade in order to increase its negative incidence of stall
    The present invention is in the field of aerodynamic profiles of blades and more particularly blades intended to form a propeller for advancing an aircraft.
    The present invention relates to a method for improving a blade in order to increase its negative stall incidence in absolute value, as well as such an improved blade and a rotor provided with such improved blades. This improved blade is intended to equip a rotor of an aircraft which must provide an aerodynamic force in two opposite directions, namely either a force towards the front of the aircraft, or a force towards the rear of the aircraft. This improved blade is in particular intended for a propeller for advancing an aircraft or also for an anti-torque auxiliary rotor of a rotary wing aircraft.
    Conventionally, a blade extends longitudinally along its span from a first end to a second end. Note that the term "longitudinal" is understood as meaning the span of the blade. In addition, the blade extends transversely from a leading edge to a trailing edge, according to the strings of the blade.
    The blade notably comprises an outer covering provided with a first skin at the level of its upper surface and a second skin at the level of its lower surface as well as successive cross sections. Each cross section is defined by an aerodynamic profile comprising two half-profiles, namely a half profile of the lower surface and a half profile of the upper surface.
    Existing aerodynamic profiles which are frequently used for the blades of aircraft rotors are for example defined according to the NACA families or else the OA families, the OA families being for example described in documents FR 2626841 and FR 2765187.
    A blade is intended to be fixed to a rotating hub of a rotor at its first end by means of a blade root, its second end being called the free end. This rotating hub of the rotor rotates each blade. Relative to the rotor, it is understood that the blade extends radially from the first end towards the second end. A rotor has at least two blades.
    Each blade of a rotor provides, under the effect of an air flow generated by the rotation of the rotor, an aerodynamic force, designated generally thrust. This aerodynamic force is notably variable according to an aerodynamic angle of incidence of the blade, namely an angle between the air flow and a straight line connecting the leading edge and the trailing edge of this aerodynamic profile corresponding to the chord of the blade. For a rotor, this angle of incidence is generally modified by acting on an axis of pitch variation of the blade. This pitch variation axis extends substantially longitudinally along the span of the blade. Thereafter, the term “incidence” will be used to designate more simply the angle of aerodynamic incidence of the blade.
    We observe from a threshold incidence of the blade, designated "stall incidence", detachment of the air streams in particular at the leading edge or the trailing edge of the blade. This detachment can cause an aerodynamic stall of the blade corresponding to a sudden fall in its thrust. In addition, the detachment of the air streams generates vortices which are responsible for an increase in the coefficient of blade drag and vibrations.
    A rotor can be a main rotor of a rotary wing aircraft making it possible to sustain the aircraft, or even to propel it. A rotor can also be an auxiliary anti-torque rotor of a rotary wing aircraft. A rotor can also be a propeller for advancing a fixed-wing or rotary-wing aircraft, each blade providing an aerodynamic force allowing the advancement of the aircraft. An aircraft may for example have one or two or even four advancement propellers.
    Each blade of a rotor generally provides during the rotation of the rotor an aerodynamic force mainly, or even only in one direction, in order to provide for example for a main rotor a thrust opposing the weight of the wing aircraft rotating. In the case of a forward propeller, this aerodynamic force allows the aircraft to advance and reach high forward speeds.
    However, this aerodynamic force can in certain particular cases be reversed, for example for a forward propeller in order to cause a slowdown of the aircraft, essentially during its landing. This particular functioning is however transitory, even marginal.
    Consequently, each blade is defined to optimally provide aerodynamic force in one direction, each blade then operating with a positive incidence. For this purpose, the camber of the aerodynamic profiles of the blade is generally increased.
    The camber is a characteristic of an aerodynamic profile equal to the distance between on the one hand the chord of the aerodynamic profile and on the other hand a half-thickness line or "average line" of this aerodynamic profile, that is to say -display being located equidistant from the half-profiles of lower and upper surfaces with respect to each normal to the middle line. The distance between the rope and the middle line is taken perpendicular to the rope and, consequently, a positive increase in camber corresponds to a positive increase in said distance. In particular, a camber is zero when the aerodynamic profile is symmetrical. Conversely, an aerodynamic profile with a non-zero camber is an asymmetrical aerodynamic profile.
    The positive increase in the camber of the aerodynamic profiles of a blade has the effect of increasing the positive incidence of stalling of this blade. In fact, the positive incidence of the blade can be increased during its rotation, consequently increasing the aerodynamic force generated by the blade and its aerodynamic performance.
    It can then be seen that the mechanical power required to rotate a rotor comprising such blades with cambered aerodynamic profiles in order to provide a given aerodynamic force under a positive incidence is reduced compared to blades with non-cambered aerodynamic profiles, in particular approaching the maximum aerodynamic force that this blade can provide.
    Such blades are for example described in document FR 2765187. According to this document, the position of the maximum camber of an aerodynamic profile along its rope can also be adjusted according to the relative thickness of the aerodynamic profile.
    Conversely, the increase in the camber of the aerodynamic profiles has the opposite effect of decreasing, in absolute value, and therefore increasing in algebraic value, the negative incidence of stalling of the blade. However, this increase in the negative incidence of stalling is not problematic, the blade operating essentially, or even only under a positive incidence.
    In addition, a rotary wing aircraft, also known as a rotorcraft, can operate both with high forward speeds during cruise flights and with very low forward speeds and perform hovering flights. A rotorcraft conventionally comprises a fuselage, at least one main rotor, an anti-torque device and a power plant.
    An anti-torque device performs an anti-torque function in order to counter a yaw rotor torque generated mainly by the rotation of the main rotor of the aircraft. An anti-torque device is constituted for example by an auxiliary rotor arranged on a rear end of a tail boom of the aircraft. This anti-torque auxiliary rotor makes it possible to create, through the aerodynamic force generated by its blades, a moment opposing the rotor torque.
    A hybrid helicopter is also known which designates a rotorcraft comprising at least one main rotor, a fuselage, a power plant and an auxiliary propulsion as well as generally a lifting surface, composed for example of two wings located on either side of the fuselage. The auxiliary propulsion can be formed by one or more advancement propellers, for example two advancement propellers positioned on either side of the fuselage.
    This auxiliary propulsion can constitute the anti-torque device of the hybrid helicopter, in particular when this auxiliary propulsion comprises two advancement propellers arranged on either side of the fuselage. In this case, the propellers provide differential aerodynamic forces causing the appearance of a moment opposing the rotor torque. In particular during a hovering flight, a first advancement propeller arranged on one side of the fuselage provides an aerodynamic force towards the front of the rotorcraft while a second advancement propeller arranged on the other side of the fuselage provides an aerodynamic force towards the rear of the rotorcraft.
    In fact, this second forward propeller must provide an aerodynamic force towards the front of the rotorcraft during forward flight of the rotorcraft and an aerodynamic force towards the rear of the rotorcraft during stationary flights while the first forward propeller Always provides aerodynamic force forward of the rotorcraft regardless of the rotational phase of the rotorcraft. To reverse the aerodynamic force of this second advancement propeller, each blade of the second advancement propeller must then pass from a positive incidence for advance flights to a negative incidence for stationary flights while each blade of the first propeller always has a positive impact whatever the flight phase of the rotorcraft.
    As mentioned above, each blade of a propeller is defined to optimally provide aerodynamic force in one direction, each blade then having a positive impact. In fact, each blade of the first and second advancement propeller are preferably defined to provide a significant aerodynamic force directed towards the front of the hybrid helicopter and comprise for example asymmetrical aerodynamic profiles allowing significant aerodynamic performance under positive impacts.
    As a result, in hover, each blade of the second propeller provides aerodynamic force directed towards the rear of the hybrid helicopter with aerodynamic profiles not optimized for this. In particular, each blade of the second advancement propeller can operate with a negative incidence close to a negative incidence of stalling of the blade. The usual asymmetrical aerodynamic profiles in this case exhibit non-optimal aerodynamic performance, the camber of their aerodynamic profiles being unsuitable for these negative incidences.
    Consequently, this second advancement propeller requires greater mechanical power to be driven in rotation in hovering flight, and in particular greater power than the first advancement propeller generating a substantially identical aerodynamic force but directed only towards the front of the rotorcraft.
    One solution in order to increase the aerodynamic performance of the blade under negative impacts is to decrease the camber of the aerodynamic profiles of the blade, or even to reverse it. However, this solution is contradictory with the performance sought in forward flight as mentioned above.
    The use of blades with symmetrical aerodynamic profiles, for example from the NACA family, would make it possible to have a substantially identical aerodynamic behavior of the blade subjected to an air flow under a positive incidence or a negative incidence, by adapting possibly the twist of the blade. However, the use of blades with such symmetrical aerodynamic profiles does not make it possible to obtain significant aerodynamic forces both forwards and backwards of the rotorcraft, whatever the incidence of the blade and, would require makes greater mechanical powers to drive these blades in rotation in order to provide the necessary aerodynamic forces.
    Under these conditions, the present invention proposes a method for improving a blade making it possible to overcome the limitations mentioned above and to modify the aerodynamic profiles of an existing blade in order to obtain aerodynamic performance superior to aerodynamic performance. of this existing blade. Consequently, the negative incidence of stalling of this modified blade is increased in absolute value, allowing the modified blade to provide a significant inverted aerodynamic force under a negative incidence without degrading the aerodynamic force supplied under a positive incidence.
    In this way, this modified blade makes it possible to obtain high aerodynamic performance in two opposite directions, as necessary, while minimizing the power necessary for the rotation of these modified blades, including under negative incidences.
    The present invention also relates to a blade improved by this method as well as a rotor comprising at least two blades thus improved and a rotary wing aircraft comprising two such advancement propellers including a propeller formed by this rotor.
    A blade extends in a longitudinal direction in span from a first end to a second end and in a transverse direction from a leading edge to a trailing edge. The blade has successive cross sections, each cross section being defined by an aerodynamic profile, each aerodynamic profile being defined in particular by two half profiles including a half profile of upper surface and a half profile of lower surface, the two half profiles respectively comprising a leading edge section, an intermediate section and a terminal section, the leading edge section of each half-profile being formed by a portion of an initial leading edge circle. For each profile, the leading edge segment begins at the leading edge, the terminal segment ends at the trailing edge and the intermediate segment is located between the leading edge segment and the terminal segment.
    This blade is connected to a rotating hub of a rotor at the first end of the blade via a blade root. This blade root has an essentially structural function, its contribution to the aerodynamic performance of the rotor being secondary. It is therefore considered in the context of the invention that a blade is therefore constituted solely by a profiled part which provides for each blade of the rotor the main aerodynamic forces of the rotor.
    According to the invention, the method for improving a blade comprises a first step of modifying at least half a profile of at least one aerodynamic profile, the first modification step being provided with the following sub-steps:
    -increase in the radius of the initial leading edge circle of this at least half a profile in order to form a new leading edge circle of this at least one half profile, a portion of which constitutes a new edge section of attack of this at least one half-profile, the new leading edge circle of this at least one half-profile being tangent initial circle of the leading edge of this at least one half-profile at the level of the leading edge , and
    definition of a new intermediate section of this at least one half-profile replacing the intermediate section of this at least one half-profile and connecting the new leading edge circle of this at least one half-profile to the terminal section of this at least half a profile in order to increase a negative incidence of stalling of the blade.
    During this first step, only one of the two half-profiles of each aerodynamic profile can be modified, namely the upper profile half or the lower profile half. The two half-profiles of each aerodynamic profile can also be modified during this first step.
    In fact, the half profiles of upper and lower surfaces are generally characterized by the coordinates of points allowing their construction. In addition, the leading edge sections of these two half-profiles may be circular in shape and formed respectively by a portion of the initial leading edge circle, the radius and the coordinates of the center of each initial edge circle d attack being known from the definition of the upper and lower half profiles, as described in document EP 0911257. The portions of these initial leading edge circles of the two half profiles are then respectively confused with the edge sections of attack of these two half-profiles of the aerodynamic profile, the respective radii of the initial leading edge circles being equal to the radii of the leading edge section of the half-profiles. In this case, the initial leading edge circles of the two half-profiles are generally of the same center and of the same radius.
    When the leading edge sections of the upper and lower half profiles are not portions of circles, at least one of these initial leading edge circles of the two half profiles can be determined a posteriori, during of a preliminary step of the method according to the invention in order to characterize the leading edge section. The initial leading edge circle of the upper half profile and / or the lower half profile is thus estimated by a geometric construction based respectively on the leading edge sections of these upper half profiles. and lower surfaces. The initial leading edge circles of the upper and lower surface profiles thus estimated are generally different, in particular in the case of aerodynamic profiles having a non-zero camber. Knowledge of the initial leading edge circle of a half-profile and its radius advantageously makes it easy to characterize this half-profile in order, for example, to identify, on the one hand, aerodynamic profiles which can be described as versatile, namely with a wide operating range but with moderate aerodynamic performance, associated with large radii of leading edge circle and on the other hand, aerodynamic profiles with small radii of leading edge circle associated with restricted operating ranges and high aerodynamic performance.
    This preliminary determination step includes the following substeps:
    -definition of a straight line connecting the leading edge and the trailing edge of the aerodynamic profile,
    creation of a construction circle passing through the leading edge of the aerodynamic profile, the center of the construction circle being located on the line segment, the construction circle being inscribed in the half-profile,
    -increase the radius of the construction circle, the center of the construction circle being moved on the line segment and the construction circle always passing through the leading edge, until the construction circle is intersecting with the half -profile, namely that the construction circle is no longer inscribed inside the half-profile, and
    determination of the initial leading edge circle of the half-profile, the initial leading edge circle being the largest construction circle inscribed inside the half-profile, the center of the initial leading edge circle being the center of this largest construction circle inscribed inside the half-profile and being located on the line segment, the radius of the initial leading edge circle being the radius of this largest construction circle inscribed at inside the half profile.
    This preliminary step thus makes it possible to estimate the initial circle of leading edge of only one of the two half-profiles defining each aerodynamic profile of a blade, namely the upper profile half or the half-profile of lower surface, and to estimate the value of the initial radius of the leading edge.
    This preliminary step also makes it possible to estimate the two initial leading edge circles of the two half-profiles defining each aerodynamic profile of a blade and to estimate the values of their radii.
    Knowledge of the initial leading edge circle of a half-profile and its radius also makes it possible to envisage modifications of this half-profile by applying the first step of the method for improving a blade according to the invention, by replacing beforehand the leading edge section of this half-profile with a portion of the initial leading edge circle thus estimated and attached to this half-profile.
    In fact, in the context of the invention, replacing the leading edge section of a half-profile with an initial leading edge circle subsequently makes it easier to modify this half-profile by modifying in particular the radius of this initial leading edge circle and thus form the new leading edge circle. The new leading edge section is then formed by a portion of the new leading edge circle, this portion preferably consisting of at most a first quarter of this new leading edge circle, this first quarter starting at the leading edge and lying on the side of this half-profile opposite the leading edge. The position of the leading edge proper of each aerodynamic profile is unchanged and the new section of leading edge of this half-profile passes through this leading edge.
    The intermediate section of the half profile is replaced by a new intermediate section connecting the new leading edge section of the half profile, namely a portion of the new leading edge circle, to the end section of the half profile, this terminal section being unchanged. This new intermediate section is tangent to the new leading edge section and to the terminal section of the half-profile.
    This new intermediate section has a tangency evolving continuously and preferably does not include any point of inflection. The new intermediate section begins on the new leading edge circle, that is to say the new leading edge section, at a starting point situated at a first minimum transverse distance, namely parallel to the direction transverse, from the leading edge for example between 0.5% and 5% of a chord c of the aerodynamic profile. As a reminder, the rope c is equal to a distance between the leading edge and the trailing edge of the aerodynamic profile. In addition, the position of the starting point of the new intermediate section on the new leading edge circle can be constrained by the fact that the derivative of the polynomial defining this new intermediate section is positive, thus avoiding the presence of a point of inflection on this new intermediate section. This new intermediate section is for example defined by a polynomial of order 3.
    In addition, the new intermediate section is connected to the terminal section at a second transverse distance from the leading edge, for example equal to a maximum of 25% of the chord c of the aerodynamic profile.
    Furthermore, when the two upper and lower half profiles are modified, the radii of the new leading edge circles of the upper and lower half profiles may be different for certain aerodynamic profiles of the blade. modified, or even for all the aerodynamic profiles of the modified blade. Preferably, the radius of the new leading edge circle of the lower half profile is less than or equal to the radius of the new leading edge circle of the upper half profile for each aerodynamic profile of the blade.
    Indeed, the leading edge radius of a lower pressure profile is generally less than or equal to the leading edge radius of the upper pressure profile for a curved aerodynamic profile which allows good positive push performance.
    For example, the radius of the new leading edge circle of a half-upper surface is between 110% and 160% of the radius of the initial leading edge circle of this half-upper surface and the radius of the new leading edge circle of a lower pressure profile is between 100% and 280% of the radius of the initial leading edge circle of this lower pressure profile. Preferably, the radius of the new leading edge circle of one upper profile half is between 110% and 140% of the radius of the initial leading edge circle of this upper profile half and the radius of the new leading edge circle of a lower pressure profile is between 115% and 220% of the radius of the initial leading edge circle of this lower pressure profile. The values of these percentages can be influenced by the relative thickness of each aerodynamic profile of the blade, namely the ratio between its maximum thickness e and its chord c.
    In addition, a first ratio of the radius of the new leading edge circle of a half-profile by the radius of the initial leading edge circle of this half-profile is preferably not the same for each aerodynamic profile. of the blade.
    In addition, the thickness e of the aerodynamic profile is preferably unchanged for each aerodynamic profile of the blade, the cord c being able to be slightly modified. It will be recalled that the thickness e of an aerodynamic profile is equal to a maximum distance between the two half-profiles defining the aerodynamic profile, namely the underside half profile and the extrados half profile, perpendicular to the mean line. of this aerodynamic profile.
    Advantageously, the aerodynamic performance of this modified blade, the aerodynamic profiles of which have been modified, are thus improved and superior under negative effects to the aerodynamic performance of the blade before modification. Indeed, this increase in the radius of the initial leading edge circle of one or both of the half-profiles defining each aerodynamic profile of the blade makes it possible to modify the air flow over these half-profiles of the modified blade. in particular under negative incidences and, consequently, to increase in absolute value, therefore to decrease in algebraic value the negative incidence of stalling of the modified blade. The positive incidence of stalling of the modified blade is also reduced following the modification of the half-profiles. However, the area of use of the blade relates to positive incidences which remain less than the positive incidence of stalling of the modified blade.
    In this way, the aerodynamic performance of the blade under a positive incidence is not significantly modified, except for the offset of the positive incidence of stall. The modified blade can thus provide an inverted aerodynamic force under a negative incidence without degradation of an aerodynamic force supplied under a positive incidence. In particular, the slope of a curve connecting the lift coefficient Cz of the blade to its angle of incidence is substantially identical for a blade modified by the method according to the present invention and an unmodified blade.
    Consequently, a rotor equipped with such blades modified by the method of improving a blade according to the invention can advantageously provide an inverted aerodynamic force, the blades of this rotor being under a negative incidence, and then reduce the power necessary for the rotation of the rotor relative to a rotor provided with unmodified blades and having to provide the same inverted aerodynamic force. This reduction in the power necessary for the rotation of the rotor is advantageously obtained only by a modification of the area of the leading edge of the aerodynamic profiles of the blade, the diameter of the rotor and the number of blades it comprises remaining unchanged.
    This improved blade is in particular intended for the advancement propellers of aircraft and in particular for the advancement propellers of hybrid helicopters, such a rotor then being a advancement propeller.
    A hybrid helicopter provided with two advancement propellers thus comprises a first advancement propeller provided with unmodified blades and a second advancement propeller provided with blades modified by the method of improving a blade according to the invention, this second advancement propeller being intended to provide an inverted aerodynamic force during a hovering flight of the hybrid helicopter. The method of improving a blade according to the present invention thus advantageously makes it possible to improve the performance of the anti-torque device of the hybrid helicopter when hovering, this anti-torque device being formed by the propellers.
    The power developed by the power plant of the hybrid helicopter to rotate this second advancement propeller is thus reduced, the power saved can then be used for example to increase the payload of the hybrid helicopter. This reduction in the power required for the rotation of the second advancement propeller may also have the consequence of optimizing the power plant of the hybrid helicopter and, consequently, a decrease in the total weight of the aircraft.
    In addition, by pushing the stall limit under a negative impact, the margins of maneuverability of the hybrid helicopter are also improved and, consequently, the safety of these flights.
    This method is intended to be applied to blades whose successive cross sections are formed by existing aerodynamic profiles, which can be both symmetrical and asymmetrical. These existing aerodynamic profiles are for example used frequently and defined according to the NACA families or else the OA families, and in particular according to the 0A3 and OA4 families.
    The method of improving a blade according to the present invention may also include a second step of moving the leading edge for each aerodynamic profile of the blade, the second step being provided with the following substeps:
    displacement of the leading edge of each aerodynamic profile of the blade by a third distance perpendicular to the line segment, from the lower surface profile to the upper surface profile, the initial leading edge sections or, as the case may be, where appropriate, the new leading edge sections of the two half-profiles of the aerodynamic profile also being displaced, and
    -definition of new intermediate sections of the two half-profiles respectively connecting the initial leading edge sections or else the new leading edge sections of the two half-profiles to the terminal sections of these two half-profiles.
    Consequently, for each half-profile, a new intermediate section connects the leading edge section or else the new leading edge section which previously replaced the leading edge section during the first step of the method, thus moved to the end section of the half-profile, this end section being unchanged.
    This displacement of the leading edge of each aerodynamic profile "towards the upper surface profile" causes a modification of the mean line of each aerodynamic profile of the blade in the area of the leading edge. This displacement of the leading edge of each aerodynamic profile thus causes a change in the camber of each aerodynamic profile of the blade, but without reversing this camber (conservation of the direction of the camber), which is reduced. This modification of the position of the leading edge of each aerodynamic profile of the modified blade and the modification of its mean line again make it possible to modify the air flow over the two half-profiles of the modified blade, in particular under negative impacts. Consequently, the negative incidence of stalling of the modified blade is increased in absolute value, therefore decreased in algebraic value, and the positive incidence of stalling of the modified blade is reduced while remaining outside the area of use of the blade.
    In fact, the aerodynamic performance of this modified blade is once again advantageously improved and the blade thus modified can provide an inverted aerodynamic force under a negative incidence without degradation of an aerodynamic force supplied under a positive incidence.
    The third distance is for example between 0.5% and 2% of the chord c of the aerodynamic profile so as not to significantly modify the aerodynamic behavior of the modified blade and in particular the aerodynamic performance under positive impacts. Preferably, the third distance is between 1% to 1.5% of the length of the cord c.
    Following this displacement of the leading edge of each aerodynamic profile, the connection conditions between the new intermediate section and on the one hand the new leading edge circle and on the other hand the terminal section are identical to those mentioned for the first step of the method according to the invention for each half-profile. In particular, the new intermediate section of each half-profile has tangents evolving continuously and preferably still does not include any point of inflection. Similarly, the new intermediate section begins on the new leading edge circle at a starting point located at a first minimum transverse distance from the leading edge, for example between 0.5% and 5% of a chord c of the profile. aerodynamic and connects to the terminal section at a second transverse distance from the leading edge, for example at most 25% of the chord c.
    The method for improving a blade according to the invention may also include a third step in the manufacture of a blade defined by the modified aerodynamic profiles as previously described. These aerodynamic profiles can be modified according to the first step alone or else the first and second steps.
    The present invention also relates to a modified blade, also known as an “improved blade” in this text, defined by the aerodynamic profiles modified by the steps of the method for improving a blade previously described. This blade is produced using these modified aerodynamic profiles.
    The following are presented by way of example the coordinates in a reference (u, v) of the points constituting an aerodynamic profile OA312 and an aerodynamic profile OA312 modified according to the method described. The origin of this reference (u, v) is positioned at the leading edge of the unmodified OA312 aerodynamic profile and its x-axis u is defined according to the initial chord of this unmodified OA312 aerodynamic profile.
    OA 312 initial OA 312 modified u V u V 1 -0.001786945 1 -0.001786945 0.99308697 -0.001988992 0.993196671 -0.001985598 0.98618332 -0.002215004 0.986394068 -0.002207676 0.97928141 -0.002488529 0.979593055 -0.002474188 0.97238481 -0.002873193 0.972797017 -0.002846444 0.96549693 -0.003391046 0.966009283 -0.00334798 0.95861932 -0.004031037 0.959231538 -0.003969973 0.95175004 -0.004755215 0.952462167 -0.004677375 0.94488588 -0.005526345 0.945698087 -0.00543364 0.9380239 -0.006316667 0.938936411 -0.006211139 0.93116231 -0.007110455 0.932175284 -0.00699338 0.92430036 -0.007901099 0.925413868 -0.007773122 0.91743785 -0.008686784 0.918651913 -0.008548178
    OA 312 initial OA 312 modified u V u V 0.91057473 -0.009467167 0.911889371 -0.009318091 0.90371098 -0.010242006 0.905126235 -0.010082772 0.89684642 -0.011009672 0.898362357 -0.010840856 0.88998083 -0.011767963 0.891597532 -0.011590451 0.88311385 -0.012513652 0.884831428 -0.012328409 0.87624547 -0.013246371 0.878063944 -0.013053601 0.86937573 -0.013966138 0.871295153 -0.013766489 0.86250431 -0.014669695 0.864524839 -0.01446477 0.855631 -0.015354588 0.857752694 -0.015145064 0.84875609 -0.016023159 0.850978899 -0.015808721 0.84187951 -0.016674371 0.844203571 -0.016456549 0.83500099 -0.017304736 0.837426402 -0.017084812 0.82812076 -0.017916223 0.830647466 -0.01769373 0.82123893 -0.018509382 0.823866985 -0.018285182 0.81435538 -0.019082246 0.817084869 -0.018857594 0.80747017 -0.0196348 0.810301096 -0.019410013 0.80058343 -0.020167853 0.80351579 -0.01994328 0.79369518 -0.020681173 0.796729019 -0.020457552 0.78680546 -0.021174303 0.789940809 -0.020952474 0.77991423 -0.021645881 0.783151154 -0.02142717 0.77302154 -0.022095488 0.77636003 -0.02188035 0.76612762 -0.022525939 0.769567587 -0.022313335 0.7592327 -0.022940139 0.762774083 -0.022729319 0.75233688 -0.023338955 0.755979673 -0.023130246 0.74544014 -0.023721549 0.749184378 -0.023515873 0.73854257 -0.02408907 0.742388212 -0.023885831 0.73164438 -0.024444449 0.735591337 -0.024242526 0.72474553 -0.024787018 0.728793868 -0.024587732 0.71784596 -0.025114649 0.721995724 -0.024919355
    OA 312 initial OA 312 modified u V u V 0.71094582 -0.025430132 0.715196908 -0.025236924 0.70404533 -0.025737764 0.708397634 -0.025544526 0.69714454 -0.026038752 0.701598053 -0.025845254 0.69024347 -0.026333082 0.694798192 -0.026139602 0.68334214 -0.026621348 0.687998051 -0.026427388 0.67644068 -0.026906334 0.681197702 -0.026710228 0.66953903 -0.027186863 0.674397224 -0.026989947 0.66263715 -0.027461505 0.667596548 -0.027264813 0.65573502 -0.027729962 0.660795631 -0.027533653 0.64883275 -0.027994805 0.6539945 -0.027797017 0.64193034 -0.028255812 0.647193248 -0.028057231 0.63502771 -0.028510995 0.640391836 -0.028313241 0.62812484 -0.028759645 0.633590203 -0.028563323 0.62122173 -0.029001421 0.626788339 -0.028807008 0.61431834 -0.029235398 0.619986234 -0.029043913 0.60741467 -0.02946073 0.613183863 -0.029273006 0.60051077 -0.02967868 0.606381216 -0.029493794 0.59360667 -0.029890434 0.599578347 -0.029707604 0.58670242 -0.030097182 0.592775298 -0.0299156 0.57979794 -0.030296257 0.5859721 -0.030118688 0.57289314 -0.030483864 0.57916867 -0.030313852 0.56598808 -0.030661313 0.572364927 -0.03049775 0.55908286 -0.030832784 0.565560931 -0.030672048 0.55217755 -0.031000383 0.558756795 -0.030840795 0.54527206 -0.031160688 0.551952565 -0.031005743 0.53836638 -0.031312521 0.545148165 -0.03116348 0.53146056 -0.031457535 0.538343579 -0.031313011 0.52455455 -0.031593224 0.531538852 -0.031455938 0.51764835 -0.03171937 0.52473394 -0.031589825
    OA 312 initial OA 312 modified u V u V 0.510742 -0.031836384 0.517928853 -0.031714422 0.50383548 -0.031943495 0.511123609 -0.031830168 0.49692881 -0.032039745 0.504318209 -0.031936351 0.490022 -0.032126268 0.497512653 -0.032032039 0.48311511 -0.032205957 0.490706967 -0.032117987 0.4762081 -0.032273796 0.483901202 -0.032197353 0.46930096 -0.032327242 0.477095319 -0.032265929 0.46239376 -0.032371823 0.470289308 -0.032320316 0.45548654 -0.032412711 0.463483226 -0.032365091 0.44857928 -0.032447356 0.456677121 -0.032405942 0.44167197 -0.032471172 0.449870986 -0.032441642 0.43476464 -0.032485408 0.443064806 -0.032467215 0.4278573 -0.032490617 0.436258596 -0.032483086 0.42094995 -0.032487809 0.429452371 -0.032490197 0.41404261 -0.032477885 0.422646143 -0.032489133 0.40713529 -0.032459292 0.415839919 -0.032481255 0.400228 -0.032432138 0.40903371 -0.032465258 0.39332074 -0.032396333 0.402227525 -0.032440931 0.38641353 -0.032352989 0.395421376 -0.03240799 0.37950639 -0.03229981 0.388615266 -0.032367826 0.37259931 -0.032239735 0.381809217 -0.032318475 0.36569231 -0.032170758 0.375003228 -0.032261403 0.35878542 -0.03209116 0.368197303 -0.03219708 0.35187862 -0.032004481 0.361391487 -0.032122196 0.34497191 -0.031910779 0.354585764 -0.032039251 0.33806528 -0.031811182 0.347780125 -0.031949679 0.33115874 -0.031705226 0.340974572 -0.031853825 0.32425232 -0.031592553 0.334169101 -0.031752274 0.31734598 -0.031474775 0.327363733 -0.031644051
    OA 312 initial OA 312 modified u V u V 0.31043975 -0.0313505 0.320558458 -0.031530134 0.30353372 -0.031215712 0.313753268 -0.031411284 0.29662781 -0.031074903 0.306948237 -0.031283611 0.28972193 -0.030932258 0.300143383 -0.031146822 0.28281621 -0.030782557 0.293338582 -0.031007455 0.27591065 -0.030625583 0.286533862 -0.030864197 0.26900525 -0.030461628 0.279729308 -0.030713192 0.26210003 -0.030290046 0.272924904 -0.030555618 0.25519503 -0.030110199 0.266120671 -0.030390859 0.24829025 -0.029921872 0.259316619 -0.030218702 0.24138582 -0.02972115 0.252512799 -0.030037765 0.23448204 -0.029499344 0.245709168 -0.02984953 0.22757795 -0.029287343 0.2389061 -0.029642347 0.22067396 -0.029071792 0.232103344 -0.029424966 0.2137702 -0.028849395 0.225300281 -0.029217381 0.20686666 -0.02861994 0.218497451 -0.029002322 0.19996326 -0.028386759 0.211694821 -0.02878103 0.19306012 -0.028145708 0.20489239 -0.028553712 0.18615717 -0.0278991 0.1980901 -0.028322196 0.17925445 -0.027646379 0.191288083 -0.028082795 0.17235203 -0.027385671 0.184486235 -0.027838658 0.16544986 -0.027118338 0.177684636 -0.027587677 0.15854801 -0.026842676 0.170883306 -0.027329498 0.15164628 -0.026564226 0.164082254 -0.02706411 0.14474506 -0.026273412 0.157281464 -0.026792042 0.13784413 -0.025975833 0.150480843 -0.02651589 0.13094412 -0.02565757 0.143680696 -0.026228166 0.12404474 -0.025325923 0.136880887 -0.02593271 0.11714637 -0.024973975 0.130081991 -0.025616805
    OA 312 initial OA 312 modified u V u V 0.11024893 -0.024604117 0.123283702 -0.025288199 0.10335269 -0.024212558 0.11648642 -0.024939313 0.09645803 -0.023794076 0.109690041 -0.024573293 0.08956534 -0.023344476 0.102894859 -0.024185659 0.08267502 -0.022859797 0.096101239 -0.023771588 0.07578807 -0.022329426 0.089309534 -0.023327169 0.06890528 -0.021747557 0.082520166 -0.022848405 0.06202816 -0.021102161 0.075734086 -0.022325075 0.05515825 -0.020384111 0.06895205 -0.021751715 0.04829807 -0.019578361 0.062175509 -0.021116713 0.04145067 -0.018670616 0.055405911 -0.020411465 0.03462209 -0.017630536 0.048569015 -0.01959531 0.02782328 -0.016411105 0.041857093 -0.018331146 0.02107598 -0.01493538 0.035361778 -0.016646922 0.01443014 -0.013049858 0.02889838 -0.014519503 0.00806224 -0.010384561 0.022565134 -0.011936864 0.0025131 -0.006290967 0.016517841 -0.008896071 0 0 0.010767086 -0.005266414 0.00181962 0.006398846 0.005564092 -0.000900209 0.00544734 0.011963855 0.001378576 0.004660301 0.0099923 0.016842324 0.0000531 0.011063518 0.01500132 0.021220512 0.002359147 0.017428969 0.02034035 0.025202719 0.006540217 0.022760138 0.02590894 0.028851295 0.011584271 0.027357699 0.03166044 0.032206505 0.017055197 0.031398858 0.03755644 0.0353001 0.022773637 0.035020099 0.04357001 0.038158629 0.028782261 0.038377771 0.04968097 0.040802626 0.034714585 0.041357472 0.05587318 0.043250297 0.04104269 0.044243616
    OA 312 initial OA 312 modified u V u V 0.06213457 0.045515176 0.04764504 0.046986069 0.06845575 0.047607406 0.053520572 0.049225586 0.07482821 0.049537826 0.060005457 0.051499484 0.08124387 0.0513195 0.066470409 0.053574728 0.08820416 0.053085968 0.072860138 0.055447169 0.09472631 0.054600391 0.079566418 0.057226152 0.10127513 0.05599533 0.086252972 0.058809723 0.10784577 0.057282031 0.092523495 0.06011674 0.1144356 0.058465575 0.099464645 0.061348393 0.1210419 0.05955505 0.106329761 0.062316521 0.12766218 0.060556505 0.112842766 0.062960094 0.1342944 0.061475689 0.119695822 0.063375175 0.14093683 0.062318761 0.126821535 0.064347542 0.14758792 0.063090357 0.133449162 0.064858948 0.15424625 0.063795598 0.140359805 0.065210542 0.16091073 0.064438634 0.147078544 0.065470225 0.1675805 0.065023344 0.15394452 0.065690149 0.17425476 0.065553844 0.160832609 0.065885435 0.18093267 0.066033711 0.167666831 0.066068107 0.18761362 0.066465745 0.174390994 0.066248131 0.19429713 0.066853751 0.180963426 0.066434585 0.20098285 0.067200779 0.187892045 0.066654887 0.20767042 0.067509754 0.194484137 0.066902299 0.21435948 0.067783934 0.20136219 0.067219293 0.22104988 0.068025716 0.208161319 0.067531027 0.22774153 0.068237501 0.214961994 0.067807003 0.23443446 0.068421675 0.221763937 0.068049706 0.24112875 0.068580606 0.228566908 0.068261654 0.24782458 0.068715389 0.2353707 0.068445387
    OA 312 initial OA 312 modified u V u V 0.25452205 0.068827692 0.242175141 0.068603235 0.26122116 0.068919377 0.248980113 0.068736314 0.26792178 0.068991911 0.255785492 0.068846514 0.27462369 0.069046512 0.26259118 0.068935722 0.28132662 0.069084122 0.269397095 0.069005436 0.28803028 0.069105593 0.276203173 0.069056868 0.29473438 0.06911129 0.283009359 0.069091011 0.30143866 0.069102085 0.289815609 0.06910863 0.30814267 0.069079057 0.296621881 0.069110154 0.31484591 0.069042581 0.303428139 0.069096657 0.32154803 0.068992395 0.310234356 0.06906913 0.32824871 0.068929257 0.317040502 0.06902766 0.3349476 0.068854513 0.323846547 0.068972103 0.34164434 0.068767354 0.330652477 0.068903782 0.3483387 0.06866752 0.337458273 0.068823343 0.35503065 0.068555537 0.344263902 0.068729778 0.36172032 0.068431861 0.351069341 0.06862326 0.36840796 0.068295895 0.357874575 0.068504395 0.37509386 0.068146673 0.364679585 0.068373299 0.38177833 0.06798472 0.371484324 0.068228876 0.38846165 0.067809991 0.378288761 0.068070824 0.39514412 0.067621504 0.385092882 0.067899724 0.40182598 0.067419068 0.391896644 0.06771487 0.40850748 0.067203368 0.398699995 0.067515467 0.41518876 0.066974178 0.405502918 0.067301989 0.42186994 0.066730788 0.412305398 0.067074804 0.42855111 0.066473508 0.419107378 0.066833144 0.43523236 0.066202444 0.425908825 0.066576891 0.44191368 0.065917206 0.432709721 0.066306435
    OA 312 initial OA 312 modified u V u V 0.44859506 0.065617651 0.439510025 0.066021467 0.45527644 0.065303594 0.446309695 0.065721734 0.46195772 0.064974867 0.45310869 0.06540709 0.46863881 0.064631277 0.459906969 0.065077335 0.47531964 0.064272451 0.466704491 0.064732303 0.4820001 0.063897928 0.473501201 0.064371654 0.4886801 0.063507243 0.480297039 0.063994929 0.49535956 0.063100338 0.487091937 0.063601606 0.50203842 0.062677149 0.493885843 0.063191506 0.50871661 0.062237069 0.500678717 0.062764654 0.51539408 0.061779608 0.507470482 0.062320496 0.52207074 0.061304328 0.514261055 0.061858479 0.52874655 0.060810988 0.521050355 0.061378131 0.53542139 0.0602992 0.527838315 0.060879186 0.5420952 0.059768836 0.534624852 0.060361255 0.54876793 0.059219921 0.541409899 0.059824155 0.55543953 0.058652464 0.548193404 0.059267917 0.56210994 0.058066592 0.554975313 0.058692549 0.56877914 0.05746262 0.561755584 0.058098178 0.5754471 0.056841088 0.56853419 0.057485118 0.58211376 0.056202066 0.575311132 0.056853938 0.58877904 0.055545681 0.582086371 0.056204727 0.59544292 0.054872031 0.588859871 0.055537614 0.60210535 0.054181448 0.595631595 0.054852706 0.60876634 0.053474508 0.602401532 0.054150359 0.61542589 0.052751624 0.609169702 0.05343118 0.62208393 0.052012809 0.615936106 0.052695577 0.62874038 0.051258157 0.622700706 0.051943555 0.63539517 0.050487757 0.629463471 0.051175219
    OA 312 initial OA 312 modified u V u V 0.6420482 0.049701608 0.636224373 0.050390649 0.64869935 0.048899517 0.642983367 0.049589813 0.65534853 0.048081384 0.649740389 0.048772502 0.66199564 0.047247258 0.656495386 0.047938621 0.66864067 0.046397534 0.66324833 0.047088273 0.67528354 0.04553245 0.669999234 0.046221885 0.68192413 0.044651761 0.67674808 0.045339604 0.6885623 0.043755044 0.683494782 0.044441075 0.69519797 0.042842331 0.690239249 0.043525919 0.70183108 0.041913861 0.696981456 0.042594262 0.70846161 0.040969798 0.703721395 0.041646337 0.71508952 0.040010167 0.710459045 0.040682281 0.72171476 0.03903488 0.717194363 0.039702055 0.72833734 0.03804412 0.723927302 0.038705626 0.73495729 0.03703822 0.730657864 0.037693268 0.74157466 0.036017529 0.737386067 0.03666534 0.74818951 0.034982406 0.74411193 0.035622217 0.75480194 0.033933266 0.75083548 0.034564292 0.76141204 0.032870639 0.757556764 0.033492056 0.76801992 0.031795061 0.764275844 0.032406096 0.7746257 0.030707078 0.770992781 0.031306963 0.7812295 0.02960726 0.777707655 0.030195292 0.78783144 0.028496234 0.784420527 0.0290716 0.7944318 0.027375452 0.791131569 0.027937026 0.8010308 0.026246084 0.797841006 0.026792999 0.80762873 0.025109633 0.804549062 0.025640905 0.81422581 0.023967208 0.811255979 0.024482195 0.82082216 0.022819453 0.817961912 0.023317802 0.82741775 0.021666048 0.824666879 0.022147866
    OA 312 initial OA 312 modified u V u V 0.83401224 0.020505137 0.831370693 0.020971335 0.84060522 0.019334206 0.838072796 0.019785103 0.84719715 0.018155984 0.844773294 0.018589833 0.85378858 0.016973462 0.851472851 0.017389301 0.86037999 0.015789273 0.858171878 0.016185812 0.86697275 0.014610967 0.864871417 0.01498518 0.87356846 0.013447686 0.871573299 0.013797696 0.88016746 0.012301411 0.878278267 0.012627762 0.88677005 0.011174321 0.88498646 0.011476467 0.89337721 0.010072607 0.891698822 0.010349729 0.89998963 0.009001145 0.898416142 0.009252936 0.90660819 0.007966609 0.905139321 0.008192654 0.91323313 0.006971915 0.911868861 0.007173523 0.91986412 0.006016725 0.918604395 0.006194794 0.9265021 0.005109616 0.925346654 0.005263502 0.93314744 0.004256482 0.932096381 0.004388012 0.93979955 0.003456187 0.938852854 0.003566159 0.9464605 0.002731504 0.945617863 0.002817862 0.95313218 0.002112785 0.952393717 0.002175116 0.95981507 0.001629311 0.959181102 0.0016685 0.96650801 0.001311121 0.965978931 0.001329665 0.97320705 0.0011756 0.972783523 0.001178862 0.97990765 0.001209616 0.979589744 0.001204674 0.98660648 0.001368188 0.986394194 0.001361998 0.99330405 0.001577422 0.993197164 0.001574008 1 0.001786945 1 0.001786945
    The present invention also relates to a rotor intended for an aircraft, this rotor comprising at least two improved blades as previously described, these improved blades being defined by the aerodynamic profiles modified by the steps of the method for improving a blade. . This rotor is for example a forward propeller of an aircraft and in particular a second forward propeller of a hybrid helicopter, this second forward propeller providing an aerodynamic force towards the front of the hybrid helicopter during forward flights and rearward aerodynamic force during stationary flights.
    The present invention also relates to a rotary wing aircraft comprising a fuselage, at least one main rotor and at least two advancement propellers. At least one of the advancement propellers of the aircraft is a rotor as previously described and comprises at least two improved blades defined by aerodynamic profiles modified by the method of improving a blade previously described.
    The invention and its advantages will appear in more detail in the context of the description which follows with examples of embodiment given by way of illustration with reference to the appended figures which represent:
    - Figures 1 and 2, a hybrid helicopter,
    FIG. 3, a blade,
    - Figure 4, a block diagram of a method for improving a blade,
    - Figure 5, a construction diagram of an initial leading edge circle of a half-profile,
    - Figures 6 to 9, three modified aerodynamic profiles of a blade,
    FIG. 10, variation curves of the lift coefficient of the blade as a function of its incidence,
    FIG. 11, curves indicating the changes in the characteristics of the modifications of an aerodynamic profile as a function of its relative thickness, and
    - Figure 12, two curves connecting the thrust F and the power P consumed by a blade.
    The elements present in several separate figures are assigned a single reference.
    Figures 1 and 2 show the same hybrid helicopter 60 in top view as well as detailed views of a blade 1 of each advancement propeller 64,65 of the hybrid helicopter 60. In Figure 1, the helicopter Hybrid 60 is in forward flight while in Figure 2, the hybrid helicopter 60 is hovering.
    The hybrid helicopter 60 is a rotary wing aircraft comprising a fuselage 61, a main rotor 62, two half-wings 66.67 arranged on either side of the fuselage 61, a tail boom 68 and two advancement propellers 64.65. The two advancing propellers 64,65 are positioned on either side of the fuselage 61, respectively at the end of a half-wing 66,67.
    A blade 1 is shown in FIG. 3, this blade 1 being able to equip the main rotor 62 or else a advancing propeller 64, 65. A reference (Χ, Υ, Ζ) is shown in Figure 3 and formed by a longitudinal direction X, a transverse direction Y and a vertical direction Z, these three directions being perpendicular to each other. The longitudinal direction X is substantially parallel to, or even coincident with, a pitch variation axis of the blade 1.
    The blade 1 extends in the longitudinal direction X in span from a first end 3 to a second end 4 and in the transverse direction Y from a leading edge 5 towards a trailing edge 6. The blade 1 comprises successive cross sections in a transverse plane parallel to the transverse Y and vertical Z directions, each cross section being defined by an aerodynamic profile 10 comprising in particular two half profiles 11, 21, namely a half profile of upper surface 11 and a half lower surface profile 21. The upper surface half profile 11 and the lower surface half profile 21 respectively comprise a leading edge section 12,22 starting at the leading edge 5, a terminal section 14,24 ending at trailing edge 6 and an intermediate section 13,23 located between the leading edge section 12,22 and the end section 14,24. The leading edge sections 12, 24 of the upper surface half profile 11 and the lower surface profile 21 are formed respectively by a portion of an initial leading edge circle 15, 25.
    The aerodynamic profiles 10 of these cross sections generally evolve according to their span position on the blade 1 and can therefore be different in particular in order to be adapted to the air flow received by each cross section during the rotation of the blade 1 .
    Also shown in FIG. 3 is a line of half thickness or "mean line" 17 of the aerodynamic profile 10. This mean line 17 is equidistant from the half profiles of the lower surface 21 and upper surfaces 11 perpendicular to the average line 17. It can be seen that the aerodynamic profiles 10 of the blade 1 are asymmetrical and have a camber, this mean line 17 being curved. A line segment 16 connecting the leading edge 5 and the trailing edge 6 is also shown in FIG. 3 for several aerodynamic profiles 10. This straight segment 16 corresponds to the chord of the aerodynamic profile 10.
    FIG. 4 represents the block diagram of a method for improving an initial blade to constitute a modified blade called "improved blade", this method comprising several steps. This method is intended to be applied to blades whose successive cross sections are formed by existing aerodynamic profiles, for example according to the NACA families or else the OA families.
    This method of improving a blade 1 is particularly intended for aerodynamic profiles 10, the leading edge sections 12,22 of the half-profiles 11,21 of which are defined by a portion of an initial edge circle attack 15.25 as shown in FIG. 3. Each initial circle of leading edge 15.25 with a half-profile 11.21 is then characterized by its radius and the position of its center. For each aerodynamic profile 10, the initial leading edge circle 15 of the upper surface half-profile 11 and the initial leading edge circle 25 of the lower surface half profile 21 have their centers combined and their radii equal.
    However, this method of improving a blade 1 can also be applied to aerodynamic profiles 10, the leading edge sections 12,22 of the half-profiles 11,21 of which are not portions of circles, an initial circle leading edge 15.25 then being previously estimated for each half-profile 11.21 of each aerodynamic profile 10. This initial leading edge circle 15.25 of a half-profile can be determined by a suitable method a geometric construction of which is shown in FIG. 5 for the upper profile half-profile 11.
    This method of improving a blade 1 then includes a preliminary step of determining an initial leading edge circle 15, 25 of at least one half-profile 11, 21 of each aerodynamic profile 10, this initial circle leading edge 15.25 being estimated from the leading edge section 12.22 of the half profile 11.21.
    During this preliminary step, an initial leading edge circle 15 of the upper surface half-profile 11 and an initial leading edge circle 25 of the lower surface half-profile 21 can be estimated respectively from the sections of leading edge 12,22 of the upper profile half 11 and the lower profile 22.
    This preliminary step of determining an initial leading edge circle 15, 25 is applied to the upper profile half-profile 11 of an aerodynamic profile 10 in FIG. 5. First, a line segment 16 connecting the leading edge 5 at the trailing edge 6 of the aerodynamic profile 10 is defined, this straight line segment 16 corresponding to the chord of the aerodynamic profile 10.
    Next, a construction circle 27 is created, this construction circle 27 passing through the leading edge 5, the center B of this construction circle 27 being located on the line segment 16. In addition, the construction circle 27 is inscribed in the upper surface half-profile 11. The construction circle 27 can also be tangent to the leading edge section 12 of the upper surface half-profile 11 in the particular case where the direction of tangency of the edge section leading edge 12 at the leading edge 5 is perpendicular to the line segment 16.
    Thereafter, the radius of the construction circle 27 is increased, the center B of the construction circle 27 then being displaced on the line segment 16 and the construction circle passing through the leading edge 5. The radius of the construction circle construction 27 is thus increased until the construction circle 27 is intersecting with the upper profile half-profile 11. The construction circle 27 ”with center B” represents the first construction circle 27 intersecting with the edge section attack 12.
    Finally, the initial leading edge circle 15 of the upper half profile 11 is determined by the largest construction circle 27 'inscribed inside the upper half profile 11. The center of the initial circle of leading edge 15 is the center B 'of this largest construction circle 27' and is located on the line segment 16. The radius of the initial leading edge circle 15 is the radius of this largest construction circle 27. The largest construction circle 27 ′ corresponds in fact, during the course of the third sub-step 513, to the construction circle 27 defined by the iteration preceding the construction circle 27 ”which is the first construction circle 27 intersecting with the leading edge section 12, also corresponding to the first construction circle 27 which is not inscribed inside the upper profile half-profile 11.
    This preliminary step of determining an initial leading edge circle 15, 25 of at least one half-profile 11, 21 can also be applied to the half-profile of the lower surface 21 of the aerodynamic profiles 10 of a blade 1 This first step 51 can also be applied simultaneously to the half-profile of the upper surface 11 and to the half-profile of the lower surface 21 of the aerodynamic profiles 10 of a blade 1.
    The initial leading edge circle 15,25 can thus be defined by a center located on the line segment 16 and by a radius. This initial leading edge circle 15.25 thus makes it possible to characterize the leading edge section 12.22 of a half-profile 11.21 of an aerodynamic profile 10 of a blade 1, a portion of this initial leading edge circle 15.25 replacing the leading edge section 12.22 of the upper profile half-profile 11.
    This method of improving a blade 1 then comprises a first step 51 of modifying at least one half-profile 11, 21 of each aerodynamic profile 10 of the blade 1.
    Such a modification of an upper surface profile 11 is shown in FIGS. 6 and 7. According to FIG. 6, only the upper surface half profile 11 is modified whereas, according to FIG. 7, the upper surface half profile 11 and the half pressure profile 21 are modified, the initial circle of leading edge 15 of the upper profile half 11 and the initial circle of leading edge 25 of the lower profile half 21 being identical and combined.
    According to this first step 51, the initial leading edge circle 15.25 of a half-profile 11.21 is modified for each aerodynamic profile 10 of the blade 1 by increasing its radius r, the position of the leading edge 5 being unchanged. Consequently, a new leading edge circle 35,45 is defined by a new radius ri and a center displaced towards the trailing edge 6. A new leading edge section 32,42 of the half-profile 11,21 is then formed by a portion of this new leading edge circle 35,45.
    One application of this first step 51 is to modify the half-profile of the upper surface 11 of an aerodynamic profile 10 as shown in FIG. 6. This first step 51 comprises several following substeps 511-512.
    During a first sub-step 511, the radius of the initial leading edge circle 15 of this upper surface half-profile 11 is increased and its center is displaced in order to form a new leading edge circle 35 of this upper surface half-profile 11. The new leading edge circle 35 is tangent to the initial leading edge circle 15 of this upper surface half 11 at the leading edge 5 of the aerodynamic profile 10. A portion of this new leading edge circle 35 then constitutes a new leading edge section 32 of this upper surface half-profile 11.
    During a second sub-step 512, a new intermediate section 33 of this upper surface half-profile 11 is defined in order to replace the initial intermediate section 13 and connect the new leading edge circle 35 to the terminal section 14 of this half-profile of upper surface 11.
    This new intermediate section 33 tangentially connects the new leading edge section 32 to the end section 14 which is unchanged, the new leading edge section 32 passing through the leading edge 5 and is tangent to the initial circle of leading edge 15 at the leading edge 5. The new intermediate section 33 must not have any point of inflection and has a tangency that changes continuously.
    This first step 51 can also be applied in order to modify the underside half-profile 21 of an aerodynamic profile 10. This second step 52 can also be applied in order to modify the upper surface half-profile 11 and the half-profile lower surface 11 of an aerodynamic profile 10. Such a modification of a lower surface half profile 11 and of a lower surface profile 21 is shown in FIG. 7, the initial leading edge circle 15 of the upper surface half-profile 11 and the initial leading edge circle 25 of the lower surface half-profile 21 being identical, and combined. During this first step 51, the initial leading edge circle 15 of the upper half profile 11 and the initial leading edge circle 14 of the lower half profile 21 are modified in different ways, the new initial leading edge circle 35 of the upper half profile 11 and the new initial leading edge circle 45 of the lower half profile 21 being different.
    Following this modification of at least one half-profile 11,21 of each aerodynamic profile 10 of the blade 1, the air flow on the half-profiles 11,21 of the blade 1 is modified and causes a reduction, in algebraic value, positive incidences ad P and negative adn of stalling of the blade 1. Consequently, the aerodynamic performances of the modified blade 1 are improved under negative incidences without degradation of its aerodynamic performances under positive incidences, the area of use of the blade 1 under positive incidences remaining less than the positive incidence ad P of stalling of the modified blade 1.
    The blade 1 thus modified is then optimized to equip a rotor 63 capable of providing an aerodynamic force in two opposite directions, respectively under a positive incidence and a negative incidence. This rotor 63 can for example constitute one of the two advancement propellers 64,65 of the hybrid helicopter 60 shown in FIGS. 1 and 2.
    Indeed, during a progress flight shown in the figure
    1, the two advancing propellers 64.65 of the hybrid helicopter 60 provide substantially identical aerodynamic forces directed towards the front of the hybrid helicopter 60. The blades 1 of these advancing propellers 64.65 have positive impacts as shown in Figure 1.
    Conversely, during a hovering flight shown in the figure
    2, the two advancing propellers 64,65 provide opposite aerodynamic forces, a first advancing propeller 64 arranged to the left of the fuselage 61 providing an aerodynamic force directed towards the front of the hybrid helicopter 60 while a second advancement propeller 65 arranged to the right of the fuselage 61 provides an aerodynamic force directed towards the rear of the hybrid helicopter 60. The blades 1 of the first advancement propeller 64 have a positive incidence as shown in FIG. 2 then that the blades 1 of the second advancement propeller 65 have a negative impact.
    Each modified blade 1 fitted to the second advancement propeller 65 thus enables it to provide the aerodynamic force F necessary for hovering under a negative angle of attack which is more distant from the negative impact of stalling of the modified blade 1 than for a unmodified blade. This is accompanied by a power necessary for the rotational driving of the second advancement propeller 65 which can be reduced compared to a advancement propeller having blades 1 unmodified, as shown in FIG. 12 in order to provide this aerodynamic force F necessary for a hovering flight under a negative incidence. FIG. 12 represents two curves 18, 19 connecting the aerodynamic force F of a blade 1, on the abscissa, with the power P consumed by this blade 1, on the ordinate. A first curve 18 corresponds to an unmodified blade 1 and a second curve 19 corresponds to a modified blade 1.
    It can be seen, for example, that, for the same power consumed Pa by the blade 1, a point A of the first curve 18 corresponds to a first aerodynamic force Fa less than a second aerodynamic force Fg corresponding to the point G of the second curve 19.
    It is also noted that, for the same aerodynamic force Fa generated at the level of a blade, the blade 1 with the modified aerodynamic profiles 11 will consume a power Pa 'corresponds to a point A' of the second curve 19 which is less than the power Pa consumed by a blade 1 with the unmodified aerodynamic profiles 11 corresponds to point A of the first curve 18.
    During the application of this first step 51, its thickness e of the aerodynamic profile 10 is unchanged for each aerodynamic profile 10 of the blade 1 while its chord c can be slightly modified. In addition, the new intermediate section 33.43 of a half-profile 11.21 begins respectively on the new leading edge circle 35.45 of this half-profile 11.21 at a first minimum transverse distance from the edge d attack between 0.5% and 5% of the chord c of the aerodynamic profile 10. The new intermediate section 33.43 of a half-profile 11.21 is connected respectively to the end section 14.24 of this half-profile 11.21 to a second transverse distance from the leading edge 5 less than or equal to 25% of the chord c.
    A modification of the aerodynamic profiles 10 of a blade 1 according to this first step 51 is sufficient to improve the aerodynamic performance of the blade 1. However, the method of improving a blade 1 may also include a second step 52 of moving the edge 5 for each aerodynamic profile 10 of the blade 1. According to this second step 52, the leading edge 5 of each aerodynamic profile 10 of the blade 1 is moved from the lower surface profile 21 to the upper surface profile 11 of a third distance d, perpendicular to the line segment 16, the half profiles of upper surface 11 and lower surface 21 being modified accordingly. This second step 52 comprises two sub-steps 521,522.
    According to FIGS. 8 and 9, this displacement of the leading edge 5 of the aerodynamic profile 10 follows the increase in the radii of the initial leading edge circles 15, 25 of the upper profile half 11 and the half lower surface profile 21 of the aerodynamic profile 10. However, this displacement of the leading edge 5 can be made following a prior modification of only one of the two half-profiles 11,21. FIG. 9 represents the aerodynamic profile 10 in its entirety, while FIG. 8 represents only an area of this aerodynamic profile 10 near the leading edge 5 as in FIGS. 6 and 7. It can be seen in FIG. 8 that the initial leading edge circles 15.25 of the upper surface half-profile 11 and of the lower surface half-profile 21 of the airfoil 10 have different radii and centers.
    During a first sub-step 521, the leading edge 5 of the aerodynamic profile 10 is displaced by the third distance d perpendicular to the line segment 16, from the lower surface profile 21 to the upper surface profile 11. The new leading edge section 32 of the upper surface half-profile 11 is also displaced, as is the new leading edge section 42 of the lower surface half profile 21.
    During a second sub-step 522, a new intermediate section 33 attached to the upper surface half profile 11 and a new intermediate section 43 attached to the lower surface profile 21 are defined. The new intermediate section 33 attached to the upper surface half-profile 11 connects the new leading edge section 32 of this upper surface half-profile 11 moved to the terminal upper surface section 14 of this upper surface half profile, the terminal section 14 being unchanged. Similarly, the new intermediate section 43 attached to the underside half-profile 21 connects the new leading edge section 42 of this underside half-profile 21 moved to the terminal section 24 of this underside half-profile 21 , the terminal section 24 being unchanged.
    The new intermediate section 33 of the upper surface half-profile 11 and the new intermediate section 43 of the lower surface profile 21 are then tangent respectively to the new leading edge section 32 of the upper surface profile 11 and to the new leading edge section 42 of the lower surface half-profile 21 as well as respectively to the end section 14 of the upper surface half-profile 11 and to the terminal section 24 of the lower surface half-profile 21. The new intermediate section 33 of the upper surface half-profile 11 and the new intermediate section 43 of the lower surface half-profile still do not have any point of inflection and have tangents evolving continuously.
    This displacement of the leading edge 5 consecutive to the second step 52 causes a modification of the mean line 17 of the aerodynamic profile 10 in the area of the leading edge 5. The third distance d is for example between 0.5% and 2% of the chord c of the aerodynamic profile 10. This displacement of the leading edge 5 also causes a slight increase in the chord c of the aerodynamic profile 10. This slight increase in the chord c is of the order of a few hundredths of a percentage, the new chord c 'of the aerodynamic profile 10 being defined by the following relation: c' = y / c 2 + d 2 . For example, for a third distance d less than or equal to 2% of the chord c of the airfoil 10, this increase in chord c is less than 0.02%.
    This slight increase in chord c is only a consequence of the displacement of the leading edge 5 of the aerodynamic profile 10 according to the third step 53 and has no direct effect on the improvement of the aerodynamic performance of the aerodynamic profile. 10. Indeed, these are the combined modifications of the leading edge 5, namely the increase of at least one radius of the initial leading edge circle 15.25 of the upper profile half-profile 11 and / or d extrados 21 and its displacement, which are at the origin of the improvement of these aerodynamic performances of the aerodynamic profile 10.
    This displacement of the leading edge 5 whether it follows a modification of the aerodynamic profiles 10 only for its upper surface half-profile 11, only for its lower surface profile 21 or else according to its half-profiles upper surface 11 and lower surface 21, causes a reduction in the positive incidence a'dp and negative a'dn of stalling of the modified blade 1 greater than for a blade 1 of which only the radius of the initial circle of leading edge 15, 25 of one or both of the two half-profiles 11, 21 has been modified by modifying the air flow on the upper profile half-profiles 11 and lower surface 21 of the modified blade 1.
    A first graph showing this reduction in the positive incidences ad P and negative adn of stalling of the blade 1 whose aerodynamic profiles 10 are modified by applying the two steps 52-53 of the method for improving a blade 1 is represented on the figure 10. This graph represents the variation of the coefficient of lift Cz of the blade 1 as a function of the incidence a of the blade 1 with respect to the air flow on the blade 1 on the one hand according to a first graph 7 for an unmodified blade 1 and on the other hand according to a second graph 8 for a modified blade 1. The incidence a is on the abscissa and lift coefficient Cz on the ordinate.
    It is noted that the positive incidences a'd P and negative a'dn of stalling of the blade 1 modified according to the two steps 52-53 shown in the second graph 8 are less than the positive incidences ad P and negative adn of stalling of the blade unmodified shown in the first graph 7.
    It is also noted that for a negative incidence substantially equal to -5 °, an unmodified blade operates close to its negative incidence in stall, the corresponding point A not being located on the linear part of the first graph 7, while the point G corresponding to the same negative incidence substantially equal to -5 ° is located on the linear part of the second graph 8 of the modified blade 1, thus operating with an incidence more distant from its negative incidence in stall.
    Consequently, the aerodynamic performance of the modified blade 1 is greater than that of the unmodified blade and the modified blade 1, as previously mentioned and shown in FIG. 12, and this modified blade 1 can provide for the same power consumption Pc , an aerodynamic force F greater than an unmodified blade. Likewise, such a modified blade 1 requires less power consumption than an unmodified blade in order to be driven in rotation in order to provide the necessary aerodynamic force F. For example, for a second propeller 65 of a hybrid helicopter 60 of average tonnage using such blades 1 modified according to the two steps 52-53, the power saving obtained can be of the order of 100 kilowatts.
    The modifications applied to the aerodynamic profiles 10 of the blade 1 according to each of the steps 51-52 can also be influenced by the relative thickness of these aerodynamic profiles 10, as shown in the second graph in FIG. 11. This second graph represents a first envelope 55 for variation of a first ratio between the radius ri of the new leading edge circle 35 of a half-profile of the upper surface 11 by the radius r of the initial leading edge circle 15 of this half-profile extrados 11 as a function of variations in the relative thickness of the aerodynamic profile 10. This second graph represents a second envelope 56 of variation of a second ratio between the radius r'i of the new leading edge circle 45 d ' a half intrados profile 21 by the radius r 'of the initial leading edge circle 25 of a half intrados profile 21 as a function of variations in the relative thickness of the aerodynamic profile 10. The thickness relative ssor of the aerodynamic profile 10 is on the abscissa and the first and second reports on the ordinate.
    The variations of these ratios are shown in FIG. 11 for aerodynamic profiles 10 whose relative thickness is between 7.5% and 12%, the method for improving a blade 1 according to the invention being particularly suitable for the blades formed. of these aerodynamic profiles 10. However, this method of improving a blade 1 can also be applied to blades 1 formed of aerodynamic profiles 10 whose relative thickness is different.
    It can be seen that the first report concerning the new leading edge circle 35 of a half-profile of upper surface 11, the variation of which is represented by the first envelope 55, is little influenced by the increase in the relative thickness. of the aerodynamic profile 10 unlike the second report relating to the new leading edge circle 45 of a lower pressure profile 21, the variation of which is represented by the second envelope 56 and which tends to decrease when the relative thickness of the aerodynamic profile increases.
    The second graph also represents a third envelope 57 of variation of the third distance d of displacement of the leading edge 5 as a function of variations in the relative thickness of the aerodynamic profile 10. The relative thickness of the aerodynamic profile 10 is on the abscissa and the third distance d, expressed as a percentage of the string c, on the ordinate. It can be seen that the width of this third envelope 57 tends to decrease when the relative thickness of the aerodynamic profile 10 increases, the average value of this third envelope 57 being substantially constant.
    Finally, the method for improving a blade 1 can also include a third step 53 of manufacturing a blade 1 defined by the aerodynamic profiles 10 modified during the previous steps. These aerodynamic profiles 10 can be modified according to the only first step 51 or else the first and second steps 51, 52.
    Naturally, the present invention is subject to numerous variations as to its implementation. Although 5 several embodiments have been described, it is understood that it is not conceivable to identify exhaustively all the possible modes. It is of course conceivable to replace a means described by an equivalent means without departing from the scope of the present invention.
    权利要求:
    Claims (14)
    [1" id="c-fr-0001]
    1. Method for improving a blade (1), said blade (1) extending in a longitudinal direction (X) in span from a first end (3) to a second end (4) and in a direction transverse (Y) from a leading edge (5) towards a trailing edge (6), said blade (1) comprising successive cross sections, each cross section being defined by an aerodynamic profile (10), each aerodynamic profile (10) being defined by two half-profiles (11,21) including a half-profile of upper surface (11) and a half-profile of lower surface (21), said two half-profiles (11,21) comprising a leading edge section (12,22), an intermediate section (13,23) and a terminal section (14,24), said leading edge section (12,22) of each half-profile (11, 21) being formed by a portion of an initial leading edge circle (1 5.25) for, characterized in that said method comprises a first step (51) of modification of ’At least half a profile (11,21) of each aerodynamic profile (10), said first step (51) being provided with the following substeps:
    -increasing (511) the radius of said initial leading edge circle (15,25) of said at least one half-profile (11,21) in order to form at least one new leading edge circle (35,45) of said at least one half-profile (11,21) of which a portion constitutes a new leading edge section (32,42) of said at least one half-profile (11,21), said new leading edge circle (35,45) being tangent to said initial leading edge circle (15,25) of said at least one half-profile (11,21) at said leading edge (5), and
    - Definition (512) of a new intermediate section (33,43) of said at least one half-profile (11,21) replacing said intermediate section (13,23) of said at least one half-profile (11,21) and connecting said new leading edge circle (35,45) of said at least one half-profile (11,21) to said end section (14,24) of said at least one half-profile (11,21) in order to increase a negative incidence of stalling of said blade (1).
    [2" id="c-fr-0002]
    2. Method according to claim 1, characterized in that during said first step (51), said two half-profiles (11,21) of each aerodynamic profile (10) are modified.
    [3" id="c-fr-0003]
    3. Method according to any one of claims 1 to 2, characterized in that for each aerodynamic profile (10) of said blade (1), the radius of said new leading edge circle (35) of said half-profile d '' upper surface (11) is between 110% to 140% of said radius of said initial leading edge circle (15) of said upper profile half-profile (11) and the radius of said new leading edge circle (45) of said underside half-profile (21) is between 115% to 220% of said radius of said initial leading edge circle (25) of said underside half-profile (11).
    [4" id="c-fr-0004]
    4. Method according to any one of claims 1 to 3, characterized in that for said at least one half-profile (11,21) of each aerodynamic profile (10) of said blade (1), said new intermediate section ( 33,43) begins on said new leading edge section (32,42) at a first minimum transverse distance from said leading edge (5) between 0.5% and 5% of a chord (c) of said aerodynamic profile (10) and is connected to said terminal section (14, 24) at a second transverse distance from said leading edge (5) equal to at most 25% of said rope (c), said rope (c) being equal to a distance between said leading edge (5) and said trailing edge (6) of said aerodynamic profile (10).
    [5" id="c-fr-0005]
    5. Method according to any one of claims 1 to 4, characterized in that said method comprises a second step (52) of displacement of said leading edge (5) for each aerodynamic profile (10) of said blade (1) , said second step (52) being provided with the following sub-steps:
    -displacement (521) of said leading edge (5) of each aerodynamic profile (10) of said blade (1) by a third distance d perpendicular to said straight line (16), from said pressure profile (21) said upper surface profile (11), said initial leading edge section (12,22) or, where appropriate, said new leading edge section (32,42) of said two half-profiles (11, 21) of said aerodynamic profile (10) also being displaced, and
    - Definition (522) of a new intermediate section (33,43) of said two half-profiles (11,21) respectively connecting said initial leading edge section (12,22) or, where appropriate, said new leading edge section (32,42) of said two half-profiles (11,21) to said terminal section (14,24) of said two half-profiles (11,21).
    [6" id="c-fr-0006]
    6. Method according to claim 5, characterized in that said third distance d is between 0.5% and 2% of a rope (c) of said aerodynamic profile (10), said rope (c) being equal to a distance between said leading edge (5) and said trailing edge (6) of said aerodynamic profile (10).
    [7" id="c-fr-0007]
    7. Method according to any one of claims 1 to 6, characterized in that for said at least one half-profile (11,21) of each aerodynamic profile (10) of said blade (1), said new intermediate section ( 33,43) has no inflection point.
    [8" id="c-fr-0008]
    8. Method according to any one of claims 1 to 7, characterized in that for said at least one half-profile (11,21) of each aerodynamic profile (10) of said blade (1), said new intermediate section ( 33,43) is formed by a polynomial of degree 3.
    [9" id="c-fr-0009]
    9. Method according to any one of claims 1 to 8, characterized in that a thickness (e) equal to a maximum distance between said upper surface profile (11) and said lower surface profile (12) of said aerodynamic profile (10) is unchanged for each aerodynamic profile (10).
    [10" id="c-fr-0010]
    10. Method according to any one of claims 1 to 9, characterized in that said method comprises a third step (53) of manufacturing said blade (1) according to said modified aerodynamic profiles (10).
    [11" id="c-fr-0011]
    11. Improved blade (1) for aircraft (60) extending in a longitudinal direction (X) in span from a first end (3) to a second end (4) and in a transverse direction (Y) of a leading edge (5) towards a trailing edge (6), said blade (1) comprising successive cross sections, each cross section being defined by an aerodynamic profile (10), each aerodynamic profile (10) being defined by two half profiles (11,21) including a half profile of upper surface (11) and a half profile of lower surface (21), said two half profiles (11,21) respectively comprising a leading edge section (12,22), an intermediate section (13,23) and an end section (14,24), said leading edge section (12,22) being formed by a portion of an initial edge circle attack (15,25) for each half-profile (11,21), characterized in that said blade (1) is produced by using said aerodynamic profiles s (10) modified by the method according to any one of claims 1 to 10.
    [12" id="c-fr-0012]
    12. Blade (1) according to claim 11, characterized in that said blade (1) comprises at least one modified aerodynamic profile (10) whose coordinates of the points constituting it are in a reference (u, v):
    u V u V 1 -0.001786945 0.898362357 -0.010840856 0.993196671 -0.001985598 0.891597532 -0.011590451 0.986394068 -0.002207676 0.884831428 -0.012328409 0.979593055 -0.002474188 0.878063944 -0.013053601 0.972797017 -0.002846444 0.871295153 -0.013766489 0.966009283 -0.00334798 0.864524839 -0.01446477 0.959231538 -0.003969973 0.857752694 -0.015145064 0.952462167 -0.004677375 0.850978899 -0.015808721 0.945698087 -0.00543364 0.844203571 -0.016456549 0.938936411 -0.006211139 0.837426402 -0.017084812 0.932175284 -0.00699338 0.830647466 -0.01769373 0.925413868 -0.007773122 0.823866985 -0.018285182 0.918651913 -0.008548178 0.817084869 -0.018857594 0.911889371 -0.009318091 0.810301096 -0.019410013 0.905126235 -0.010082772 0.80351579 -0.01994328 0.796729019 -0.020457552 0.517928853 -0.031714422 0.789940809 -0.020952474 0.511123609 -0.031830168 0.783151154 -0.02142717 0.504318209 -0.031936351
    u V u V 0.77636003 -0.02188035 0.497512653 -0.032032039 0.769567587 -0.022313335 0.490706967 -0.032117987 0.762774083 -0.022729319 0.483901202 -0.032197353 0.755979673 -0.023130246 0.477095319 -0.032265929 0.749184378 -0.023515873 0.470289308 -0.032320316 0.742388212 -0.023885831 0.463483226 -0.032365091 0.735591337 -0.024242526 0.456677121 -0.032405942 0.728793868 -0.024587732 0.449870986 -0.032441642 0.721995724 -0.024919355 0.443064806 -0.032467215 0.715196908 -0.025236924 0.436258596 -0.032483086 0.708397634 -0.025544526 0.429452371 -0.032490197 0.701598053 -0.025845254 0.422646143 -0.032489133 0.694798192 -0.026139602 0.415839919 -0.032481255 0.687998051 -0.026427388 0.40903371 -0.032465258 0.681197702 -0.026710228 0.402227525 -0.032440931 0.674397224 -0.026989947 0.395421376 -0.03240799 0.667596548 -0.027264813 0.388615266 -0.032367826 0.660795631 -0.027533653 0.381809217 -0.032318475 0.6539945 -0.027797017 0.375003228 -0.032261403 0.647193248 -0.028057231 0.368197303 -0.03219708 0.640391836 -0.028313241 0.361391487 -0.032122196 0.633590203 -0.028563323 0.354585764 -0.032039251 0.626788339 -0.028807008 0.347780125 -0.031949679 0.619986234 -0.029043913 0.340974572 -0.031853825 0.613183863 -0.029273006 0.334169101 -0.031752274 0.606381216 -0.029493794 0.327363733 -0.031644051 0.599578347 -0.029707604 0.320558458 -0.031530134 0.592775298 -0.0299156 0.313753268 -0.031411284 0.5859721 -0.030118688 0.306948237 -0.031283611 0.57916867 -0.030313852 0.300143383 -0.031146822 0.572364927 -0.03049775 0.293338582 -0.031007455
    u V u V 0.565560931 -0.030672048 0.286533862 -0.030864197 0.558756795 -0.030840795 0.279729308 -0.030713192 0.551952565 -0.031005743 0.272924904 -0.030555618 0.545148165 -0.03116348 0.266120671 -0.030390859 0.538343579 -0.031313011 0.259316619 -0.030218702 0.531538852 -0.031455938 0.252512799 -0.030037765 0.52473394 -0.031589825 0.245709168 -0.02984953 0.2389061 -0.029642347 0.017055197 0.031398858 0.232103344 -0.029424966 0.022773637 0.035020099 0.225300281 -0.029217381 0.028782261 0.038377771 0.218497451 -0.029002322 0.034714585 0.041357472 0.211694821 -0.02878103 0.04104269 0.044243616 0.20489239 -0.028553712 0.04764504 0.046986069 0.1980901 -0.028322196 0.053520572 0.049225586 0.191288083 -0.028082795 0.060005457 0.051499484 0.184486235 -0.027838658 0.066470409 0.053574728 0.177684636 -0.027587677 0.072860138 0.055447169 0.170883306 -0.027329498 0.079566418 0.057226152 0.164082254 -0.02706411 0.086252972 0.058809723 0.157281464 -0.026792042 0.092523495 0.06011674 0.150480843 -0.02651589 0.099464645 0.061348393 0.143680696 -0.026228166 0.106329761 0.062316521 0.136880887 -0.02593271 0.112842766 0.062960094 0.130081991 -0.025616805 0.119695822 0.063375175 0.123283702 -0.025288199 0.126821535 0.064347542 0.11648642 -0.024939313 0.133449162 0.064858948 0.109690041 -0.024573293 0.140359805 0.065210542 0.102894859 -0.024185659 0.147078544 0.065470225 0.096101239 -0.023771588 0.15394452 0.065690149 0.089309534 -0.023327169 0.160832609 0.065885435 0.082520166 -0.022848405 0.167666831 0.066068107
    u V u V 0.075734086 -0.022325075 0.174390994 0.066248131 0.06895205 -0.021751715 0.180963426 0.066434585 0.062175509 -0.021116713 0.187892045 0.066654887 0.055405911 -0.020411465 0.194484137 0.066902299 0.048569015 -0.01959531 0.20136219 0.067219293 0.041857093 -0.018331146 0.208161319 0.067531027 0.035361778 -0.016646922 0.214961994 0.067807003 0.02889838 -0.014519503 0.221763937 0.068049706 0.022565134 -0.011936864 0.228566908 0.068261654 0.016517841 -0.008896071 0.2353707 0.068445387 0.010767086 -0.005266414 0.242175141 0.068603235 0.005564092 -0.000900209 0.248980113 0.068736314 0.001378576 0.004660301 0.255785492 0.068846514 0.0000531 0.011063518 0.26259118 0.068935722 0.002359147 0.017428969 0.269397095 0.069005436 0.006540217 0.022760138 0.276203173 0.069056868 0.011584271 0.027357699 0.283009359 0.069091011 0.289815609 0.06910863 0.56853419 0.057485118 0.296621881 0.069110154 0.575311132 0.056853938 0.303428139 0.069096657 0.582086371 0.056204727 0.310234356 0.06906913 0.588859871 0.055537614 0.317040502 0.06902766 0.595631595 0.054852706 0.323846547 0.068972103 0.602401532 0.054150359 0.330652477 0.068903782 0.609169702 0.05343118 0.337458273 0.068823343 0.615936106 0.052695577 0.344263902 0.068729778 0.622700706 0.051943555 0.351069341 0.06862326 0.629463471 0.051175219 0.357874575 0.068504395 0.636224373 0.050390649 0.364679585 0.068373299 0.642983367 0.049589813 0.371484324 0.068228876 0.649740389 0.048772502 0.378288761 0.068070824 0.656495386 0.047938621
    u V u V 0.385092882 0.067899724 0.66324833 0.047088273 0.391896644 0.06771487 0.669999234 0.046221885 0.398699995 0.067515467 0.67674808 0.045339604 0.405502918 0.067301989 0.683494782 0.044441075 0.412305398 0.067074804 0.690239249 0.043525919 0.419107378 0.066833144 0.696981456 0.042594262 0.425908825 0.066576891 0.703721395 0.041646337 0.432709721 0.066306435 0.710459045 0.040682281 0.439510025 0.066021467 0.717194363 0.039702055 0.446309695 0.065721734 0.723927302 0.038705626 0.45310869 0.06540709 0.730657864 0.037693268 0.459906969 0.065077335 0.737386067 0.03666534 0.466704491 0.064732303 0.74411193 0.035622217 0.473501201 0.064371654 0.75083548 0.034564292 0.480297039 0.063994929 0.757556764 0.033492056 0.487091937 0.063601606 0.764275844 0.032406096 0.493885843 0.063191506 0.770992781 0.031306963 0.500678717 0.062764654 0.777707655 0.030195292 0.507470482 0.062320496 0.784420527 0.0290716 0.514261055 0.061858479 0.791131569 0.027937026 0.521050355 0.061378131 0.797841006 0.026792999 0.527838315 0.060879186 0.804549062 0.025640905 0.534624852 0.060361255 0.811255979 0.024482195 0.541409899 0.059824155 0.817961912 0.023317802 0.548193404 0.059267917 0.824666879 0.022147866 0.554975313 0.058692549 0.831370693 0.020971335 0.561755584 0.058098178 0.838072796 0.019785103 0.844773294 0.018589833 0.925346654 0.005263502 0.851472851 0.017389301 0.932096381 0.004388012 0.858171878 0.016185812 0.938852854 0.003566159 0.864871417 0.01498518 0.945617863 0.002817862
    u V u V 0.871573299 0.013797696 0.952393717 0.002175116 0.878278267 0.012627762 0.959181102 0.0016685 0.88498646 0.011476467 0.965978931 0.001329665 0.891698822 0.010349729 0.972783523 0.001178862 0.898416142 0.009252936 0.979589744 0.001204674 0.905139321 0.008192654 0.986394194 0.001361998 0.911868861 0.007173523 0.993197164 0.001574008 0.918604395 0.006194794 1 0.001786945
    [13" id="c-fr-0013]
    13. Rotor (63) intended for an aircraft (60), said rotor (63) comprising at least two blades (1) according to any one of claims 11 to 12.
    [14" id="c-fr-0014]
    14.A rotary wing aircraft (60) comprising a fuselage 5 (61), at least one main rotor (62) and at least two advancement propellers (64,65), characterized in that at least one of said propellers d advancement (64,65) is a rotor (63) according to claim 13.
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    BE436683A|
    同族专利:
    公开号 | 公开日
    EP3527491B1|2020-04-29|
    EP3527491A1|2019-08-21|
    RU2716470C1|2020-03-11|
    US20200023940A1|2020-01-23|
    US11225316B2|2022-01-18|
    FR3077803B1|2020-07-31|
    CN110155319A|2019-08-23|
    引用文献:
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    US4925131A|1966-05-18|1990-05-15|Karl Eickmann|Aircraft with a plurality of propellers, a pipe structure for thereon holdable wings, for vertical take off and landing|
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    US8016566B2|2006-08-03|2011-09-13|Bell Helicopter Textron Inc.|High performance low noise rotorcraft blade aerodynamic design|
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    RU2559181C1|2014-04-10|2015-08-10|Федеральное государственное унитарное предприятие "Центральный аэрогидродинамический институт имени профессора Н.Е. Жуковского" |Aerodynamic profile of bearing surface cross-section |CN112746929A|2019-10-31|2021-05-04|江苏金风科技有限公司|Blade stall monitoring method, device, equipment and storage medium|
    CN112977814B|2021-03-04|2022-03-08|南京航空航天大学|Improved rotor pneumatic appearance suitable for small and medium-sized unmanned tilt rotor aircraft|
    法律状态:
    2019-02-20| PLFP| Fee payment|Year of fee payment: 2 |
    2019-08-16| PLSC| Publication of the preliminary search report|Effective date: 20190816 |
    2020-02-19| PLFP| Fee payment|Year of fee payment: 3 |
    2021-02-24| PLFP| Fee payment|Year of fee payment: 4 |
    2022-02-16| PLFP| Fee payment|Year of fee payment: 5 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1870167|2018-02-15|
    FR1870167A|FR3077803B1|2018-02-15|2018-02-15|METHOD OF IMPROVING A BLADE IN ORDER TO INCREASE ITS NEGATIVE INCIDENCE OF STALL|FR1870167A| FR3077803B1|2018-02-15|2018-02-15|METHOD OF IMPROVING A BLADE IN ORDER TO INCREASE ITS NEGATIVE INCIDENCE OF STALL|
    EP19153898.2A| EP3527491B1|2018-02-15|2019-01-28|Method for improving a blade in order to increase its negative stalling incidence|
    RU2019102615A| RU2716470C1|2018-02-15|2019-01-30|Method of blade improvement in order to increase its negative critical angle of attack|
    US16/274,302| US11225316B2|2018-02-15|2019-02-13|Method of improving a blade so as to increase its negative stall angle of attack|
    CN201910118110.0A| CN110155319A|2018-02-15|2019-02-15|Blade is improved to increase the method for its negative stalling angle|
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