• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention relates to a blade shroud (100) having abradable material ribs for use with a bucket tip (75) to limit and reduce the thermal stresses thereof between the bucket sheath and the bucket tip. The ablatable blade shroud (100) has a base plate (120) and a number of ribs (110) disposed thereon. The ribs (110) are made of an abradable material (130). The ribs (110) form a pattern (140) and have a shape with a number of sheets each comprising at least a first sheet and a second sheet, the second sheet having an oppositely curved shape as compared to the first sheet.
    公开号:CH703758B1
    申请号:CH01494/11
    申请日:2011-09-09
    公开日:2016-02-15
    发明作者:James Albert Tallman
    申请人:Gen Electric；
    IPC主号:
    专利说明:

    Technical area
    The present application relates to a blade shroud having ribs of an abradable material for use in a gas turbine plant.
    Background of the invention
    Generally described, the efficiency of a gas turbine plant tends to increase with increased combustion temperatures. However, higher combustion temperatures may pose a variety of problems associated with the resistance, metallurgy, and life expectancy of the components within the path of the hot combustion gas and elsewhere. These problems are especially for components such as e.g. The rotating blades and the stationary turbine shrouds arranged in the first stages of the turbine pose a challenge.
    High turbine efficiency also requires that the blades within the turbine housing or bucket shell rotate with minimal interference to prevent undesirable "leakage" of the hot combustion gas past the tips of the blades. The need to maintain adequate clearance without a significant loss of efficiency is hampered by the fact that centrifugal forces cause the blades to expand in a direction outward toward the shroud as the turbine rotates. However, the blade tips may erode as the blade tips rub against the shell. Such erosion can cause an increased clearance between them and a shortened life of the components. Other causes of leakage include thermal expansion and even aggressive operation of the engine, e.g. in military applications and the like.
    Abrasive coatings have been applied to the surface of the blade shroud to assist in establishing a minimum or optimum clearance between the shroud and the blade tips, i. to help the blade tip gap. Such material can be easily removed from the tips of the blades with little or no damage to them. Thereby, the play of the blade tip gap can be reduced with the certainty that the abradable coating will be sacrificed instead of the blade tip material.
    In addition to facilitating tip-to-shell contact, it has been found that the use of an abradable surface as a pattern of ribs and the like provides further aerodynamic benefits in further reducing leakage between the tip and shroud. In particular, the ribs may impart a direction away from the gap of the top game to the mainstream. It has been found that known ablatable patterns provide aerodynamic benefits in reducing the minimum height of the top game and in other ways.
    There is therefore a desire for an improved ablatable blade shroud pattern to reduce leakage flow through the blade tip gap and elsewhere. Such an ablatable blade shroud pattern may be optimized for a particular blade design in view of the leakage flow past it and the heat loads on it. In particular, such a blade shroud embodiment would provide an adequate ablatable shroud surface associated with a flow-reducing pattern for improved performance.
    Summary of the invention
    The present invention relates to a blade shroud having ribs of an abradable material for use with a bucket tip to limit leakage flow between the bucket shroud and the bucket tip and to reduce thermal stresses thereon. The ablatable blade shroud has a base plate and a number of ribs disposed thereon. The ribs are made of an abradable material. The ribs form a pattern and each have a number of sheets comprising at least a first sheet and a second sheet, the second sheet having an oppositely curved shape as compared to the first sheet.
    The present invention further relates to a method for producing a novel blade shroud with ribs of an abradable material.
    The method comprises the steps of determining a direction of leakage flow through the blade tip gap at a number of reference points along the blade tip, forming and arranging a number of ribs of an abradable material on the shell such that each of the ribs has a shape in at least a first arc and a second arc, and the first arc is shaped to be aligned in operation in the bucket tip reference frame perpendicular to the leakage flow at each of the reference points.
    Further advantageous embodiments of the present invention will become apparent to those skilled in the art upon review of the following detailed description taken in conjunction with the various drawings.
    Brief description of the drawings
    [0011]<Tb> FIG. 1 <SEP> is a schematic view of a gas turbine plant.<Tb> FIG. FIG. 2 is a side view of a known blade and shell of a portion of a turbine stage. FIG.<Tb> FIG. FIG. 3 is a side elevational view of an ablatable sheath proximate a blade tip as described herein. FIG.<Tb> FIG. FIG. 4 is a plan view of an ablatable pattern on the shell having a contour of the outer surface of a turbine blade tip shown in phantom across the ribs of the pattern as described herein. FIG.<Tb> FIG. FIG. 5 is a schematic view of a blade tip with leakage flows shown thereon. FIG.
    Detailed description
    Referring now to the drawings, wherein like reference numbers refer to like elements throughout the several views: FIG. 1 shows a schematic view of a gas turbine plant 10 as described herein. The gas turbine plant 10 contains a compressor 15. The compressor 15 compresses an incoming air stream 20. The compressor 15 supplies the compressed air stream 20 to a combustion chamber 25. The combustor 25 mixes the compressed air stream 20 with a compressed fuel stream 30 and ignites the mixture to produce a combustion gas stream 35. While only a single combustor 25 is shown, the gas turbine engine 10 could include any number of combustors 25. The combustion gas stream 35 is in turn fed to a turbine 40. The combustion gas stream 35 drives the turbine 40 to perform mechanical work. The mechanical work done in the turbine 40 drives the compressor 15 and an external load 45, e.g. an electric generator and the like.
    The gas turbine plant 10 may use natural gas, various types of synthesis gas and / or other types of fuels. The gas turbine plant 10 could be one of a number of different gas turbines offered by the General Electric Company of Schenectady, New York, e.g. a 7FA high performance gas turbine and the like. The gas turbine plant 10 could also have a different structure and use other types of components. Other types of gas turbine plants could also be used herein. There could also be shared herein multiple gas turbine plants 10, other types of turbines, and other types of power plants.
    FIG. 2 shows an example of a portion of a turbine stage 50. Each turbine stage 50 includes a rotating turbine blade or blade 55. As is well known, each turbine blade 55 may include a stem 60, a platform 65, an expanded airfoil 70, and an airfoil tip 75. The airfoil tip 75 may include one or more cutting teeth 80 thereon. Other configurations and other types of blades 55 could be used herein.
    Each rotating blade 55 is disposed adjacent to a stationary shell 85. The shroud 85 may have a number of seals 90 thereon that cooperate with the bucket tip 85 of each bucket 55. Alternatively, as in the present embodiment, the shroud 85 has a number of ablatable ribs in the case of an abradable shroud and the like, as described in more detail below. Other configurations and types of sheaths 85 and seals 90 could also be used herein.
    As is well known, the airfoil 70 converts the energy of the expanding combustion gas stream 35 into mechanical energy. The blade tip 75 has a surface that is substantially perpendicular to the surface of the airfoil 70. Accordingly, the blade tip also contributes to holding the combustion gas stream 35 to the airfoil 70 such that a greater portion of the combustion gas stream 35 can be converted to mechanical energy. Likewise, the stationary jacket 85 increases overall efficiency by directing the combustion gas stream 35 onto the airfoil 70 rather than through a blade tip nip 95 between the blade tip 75 and the shell 85. Minimizing the blade tip gap 95 thus contributes to minimizing leakage flow therethrough, as described above. Other configurations could be used herein.
    Fig. 3 shows an ablatable sheath 100 as described herein. The ablatable sheath 100 has a number of ribs 110 disposed on a base plate surface 120. The ribs 110 are made of an abradable material 130. The abradable material may generally be made of a metallic and / or a ceramic alloy. Any type of abradable material could be used herein. The ablatable material 130 may also be disposed on the baseplate surface 120 and elsewhere.
    As shown in FIG. 4, the ribs 110 of the ablatable sheath 100 form an ablatable pattern 140 thereon. A contact area 150 with the contour of the blade tip 75 is shown in dashed lines. An arrow 160 shows the direction of rotation of the turbine blade 55 relative to the ablatable pattern 140. An arrow 170 indicates the direction of the combustion gas flow 35 relative to the ablatable pattern 140.
    As shown, the ribs 110 may be substantially parallel to each other and may also be substantially equidistant. However, the spacing and shape of the ribs 110 may vary with position. The ribs 110 may have any desired depth and / or cross-sectional shape. Other configurations could be used herein. In this example, the ribs 110 may include a substantially sinusoidal shape 180 having at least one concave first arc 190 followed by a convex second arc 200 extending from a forward portion 220 toward a rearward portion 230. The ablatable pattern 140 thus has a double arc shape, wherein the second arc has a shape 210 which is curved in the opposite direction compared to the first arc 190. Other types of patterns could be used herein. Other types and numbers of sheets could be used herein.
    The ablatable pattern 140 may be optimized based on the shape of the associated blade tip 75. The relative positioning of the ablatable sheath 100 and the blade 55 is shown in FIG. 3 with the blade tip gap 95 interposed therebetween. The ablatable sheath 100 is stationary while the bucket 55 is rotating. The relative movement between the blade tip 75 and the ablatable sheath 100 may give rise to a periodic pressure pulsation 145 due to the advancement of the pattern 140 of the ribs 110, which acts on a leakage flow 240 extending therebetween. This transient pressure can result in a net reduction in the leakage flow 240 through the tip gap 95 as compared to an axially symmetric shroud having the same or similar gap 95 therebetween. Specifically, the ribs 110 of the ablatable sheath 100 cooperate to limit the leakage flow 240 therethrough.
    The particular sinusoidal shape 180 or other shape of the ribs 110 may be maximized with respect to the direction of leakage flow. Fig. 5 represents e.g. the leakage flow 240 through the blade tip gap 95. The velocity vectors of the leakage are shown in a reference system relative to the blade tip 75. The direction of the leakage flow 240 at a chord center reference point 245 is shown by an arrow 250 at about 20 ° from the axis of rotation. When transformed into a stationary frame of reference, the leakage flow 240 is seen as an arrow 260 at an angle of about 55 °. A stationary rib 110 that is oriented at negative 35 ° (-35 °) will thus be in a vertical or blockage position 255 to the leakage flow path. Such a blockage position 255 may thus provide the maximum blockage angle as the rib 110 moves relative to the tip gap 95. This process may thereafter be repeated at various reference points 245 along the length of the blade tip 75 to produce the shape of at least the first arc 190 of the pattern 140. Thus, many different patterns 140 may be formed by this method, depending on the type of blade, the type of turbine, the particular operating conditions, and other variables.
    The angle of the leakage flow 240 varies, e.g. Thus, the optimum blockage angle along the length of the blade tip 75 may also vary. The sinusoidal shape 180 of FIG. 4 thus maximizes the optimum blocking angle for a given shape of the respective blade tip 75 along the length thereof. The ablatable pattern 140 accordingly has the concave or first arch 190 at the front portion 220 of the pattern and the convex or second arch 200 with the opposite curvature 210 at the rear portion 230. Again, numerous other patterns could be embodied herein.
    The overall shape of the pattern 140 in general and the double arch shape or bend 210 around the rear portion 230 in particular also work to reduce the thermal stresses on the entire shroud 100. More specifically, all of the fins 110 increase heat transfer because they more have wetted surface. The pattern 140 may be optimized so that the first sheet 190 around the front portion 320 allows for improved blocking, while the second sheet 200 or the opposing curvature 210 around the rear portion 230 prevents overheating. In addition to blocking the leakage flow 240, the fins 110 may cause an optimal circulation flow 270 between adjacent fins 110. This recirculation flow 270 between fins may be generated from cool air that may be trapped between adjacent blades 55. The pattern 140 thus compensates for the leakage reduction with a reduced heat transfer.
    The ablatable sheath 100 with the ablatable pattern 140 thereby limits the leakage flow 240 through the nip and the problems associated therewith, such as e.g. a deterioration of the aerodynamic efficiency and increased heat loads of the casing. Specifically, the ablatable pattern 140 may be optimized with respect to the leakage flow 240 flowing across the blade tip 75 and to the overall heat transfer. Other types of ablatable patterns 140 could be used in conjunction with other types and shapes of blade tips. As compared to a sheath without a pattern thereon, the ablatable sheath 100 described herein is noticeably cooler and allows less leakage flow 240 therethrough around the front portion 320 thereof. The rear portion 230 may be slightly warmer, but less warm than it would otherwise be with similar leakage flows.
    The reduction in the leakage flow 240 thus reduces the aerodynamic losses around the blade 55 and shroud 100 to allow for greater efficiency. Likewise, the thermal load on the shell 100 can be reduced to improve the overall durability and life of the component.
    The present application discloses an ablatable blade shroud 100 for use with a blade tip 75 to limit leakage flow 240 therebetween and to reduce the thermal stresses thereof. The ablatable blade shroud 100 includes a base plate 120 and a number of ribs 110 disposed thereon. The ribs 110 are made of an abradable material 130. The ribs 110 form a pattern 140. The ribs 110 have a number of sheets 190, 200 with at least a first sheet 190 and a second sheet 200, the second sheet 200 having an oppositely curved shape 210.
    [0027] List of Reference Numerals<Tb> 10 'September> gas turbine plant<Tb> 15 <September> compressor<Tb> 20 <September> airflow<Tb> 25 <September> combustion chamber<Tb> 30 <September> fuel stream<Tb> 35 <September> combustion gas stream<Tb> 40 <September> Turbine<Tb> 45 <September> Last<Tb> 50 <September> turbine stage<Tb> 55 <September> blade<Tb> 60 <September> End<Tb> 65 <September> Platform<Tb> 70 <September> blade<Tb> 75 <September> blade tip<Tb> 80 <September> tooth<Tb> 85 <September> jacket<Tb> 90 <September> seal<Tb> 95 <September> blade tip clearance<tb> 100 <SEP> Ablatable sheath<Tb> 110 <September> rib<Tb> 120 <September> base surface<tb> 130 <SEP> Removable material<tb> 140 <SEP> Removable pattern<Tb> 145 <September> pulsation<Tb> 150 <September> contact area<Tb> 160 <September> Arrow<Tb> 170 <September> Arrow<Tb> 180 <September> sinusoid<tb> 190 <SEP> First sheet<tb> 200 <SEP> Second sheet<tb> 210 <SEP> Opposite curvature<tb> 220 <SEP> Front Section<tb> 230 <SEP> Rear Section<Tb> 240 <September> leakage<Tb> 245 <September> reference point<Tb> 250 <September> Arrow<Tb> 260 <September> Arrow<Tb> 255 <September> blockade position<Tb> 270 <September> recirculation flow
    权利要求:
    Claims (13)
    [1]
    A bucket shroud (100) having abradable material ribs for use with a bucket tip (75) to limit leakage flow (240) between the bucket shroud (100) and the bucket tip (75) and to reduce thermal stresses on the bucket shroud (100) and the blade tip (75), comprising:a base plate (120) anda number of said ribs (110) disposed thereon;wherein the ribs (110) comprise the ablatable material (130);the ribs (110) form a pattern (140);each of the ribs (110) has a shape with a number of sheets (190, 200);the sheets (190, 200) comprise a first sheet (190) and a second sheet (200); andthe second sheet (200) has an oppositely curved shape (210) compared to the first sheet (190).
    [2]
    The blade shroud (100) of claim 1, wherein the first arc (190) and the second arc (200) have a sinusoidal shape (180).
    [3]
    The blade shroud (100) of claim 1, wherein the first arc (190) has a concave shape with respect to the direction of rotation of the blade tip (75).
    [4]
    The blade shroud (100) of claim 1, wherein the second arc (200) has a convex shape with respect to the direction of rotation of the blade tip (75).
    [5]
    5. The blade shroud (100) of claim 1, wherein when using the bucket sheath (100) with a bucket tip (75), the first arc (190) relative to the gas flow at the bucket tip (75) opposite an upstream leading portion (220) of the bucket tip (75). 75) and the second arc (200) is disposed opposite a downstream rear portion (230) of the blade tip (75).
    [6]
    The blade shroud (100) of claim 1, wherein the ribs (110) are disposed substantially parallel to each other.
    [7]
    The blade shroud (100) of claim 1, wherein the ribs (110) are disposed substantially equidistant from each other.
    [8]
    The blade shroud (100) of claim 1, wherein when using the bucket sheath (100) with a bucket tip (75), the first sheet (190) is shaped to operate in at least one location (255) in the bucket tip reference frame (75). 75) is oriented perpendicular to the leakage flow (240).
    [9]
    The bucket shroud (100) of claim 1, wherein when using the bucket shroud (100) with a bucket tip (75), the first sheet (190) is shaped to have a number of datum points (245) and operate on each the reference point (245) in the reference frame of the blade tip (75) is oriented perpendicular to the leakage flow (240).
    [10]
    The bucket shroud (100) of claim 1, wherein the plurality of fins (110) are formed and disposed relative to one another such that a recirculation flow (270) is formed between adjacent fins (110) during operation.
    [11]
    11. A method of making a blade shroud comprising fins of an abradable material according to any one of claims 1 to 10, comprising:Determining a direction of leakage flow (240) through the blade tip gap (95) at a number of reference points (245) along the blade tip (75);Forming and disposing the ribs (110) of an abradable material on the blade shroud (100) such that each of the ribs (110) has a shape with in at least a first arc (190) and a second arc (200) and the first arc (190) is shaped so that in operation at each of the reference points (245) in the reference frame of the blade tip (75) is oriented perpendicular to the leakage flow (240).
    [12]
    The method of claim 11, wherein the ribs (110) are formed and arranged such that, in operation, upon rotation of the blade tip (75), a pressure pulsation (145) is formed about the ribs (110).
    [13]
    13. The method of claim 11, wherein the ribs (110) are formed and arranged such that, in operation, as the blade tip (75) rotates, a recirculation flow (270) is formed between the adjacent ribs (110).
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    法律状态:
    2017-03-15| NV| New agent|Representative=s name: GENERAL ELECTRIC TECHNOLOGY GMBH GLOBAL PATENT, CH |
    2021-04-30| PL| Patent ceased|
    优先权:
    申请号 | 申请日 | 专利标题
    US12/882,311|US8579581B2|2010-09-15|2010-09-15|Abradable bucket shroud|
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