WO2019035800A1 - Aubes de turbine - Google Patents

Aubes de turbine Download PDF

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Publication number
WO2019035800A1
WO2019035800A1 PCT/US2017/046686 US2017046686W WO2019035800A1 WO 2019035800 A1 WO2019035800 A1 WO 2019035800A1 US 2017046686 W US2017046686 W US 2017046686W WO 2019035800 A1 WO2019035800 A1 WO 2019035800A1
Authority
WO
WIPO (PCT)
Prior art keywords
chord
tip
wall
blade
turbine blade
Prior art date
Application number
PCT/US2017/046686
Other languages
English (en)
Inventor
Taylor HYNDS
Ali Akturk
Jose L. Rodriguez
David Monk
Krishan Mohan
Original Assignee
Siemens Aktiengesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Priority to PCT/US2017/046686 priority Critical patent/WO2019035800A1/fr
Publication of WO2019035800A1 publication Critical patent/WO2019035800A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/12—Blades
    • F01D5/14—Form or construction
    • F01D5/20—Specially-shaped blade tips to seal space between tips and stator

Definitions

  • the present invention relates to turbine blades for gas turbine engines, and in particular to turbine blade tips.
  • a turbomachine such as a gas turbine engine
  • air is pressurized in a compressor section and then mixed with fuel and burned in a combustor section to generate hot combustion gases.
  • the hot combustion gases are expanded within a turbine section of the engine where energy is extracted to power the compressor section and to produce useful work, such as turning a generator to produce electricity.
  • the hot combustion gases travel through a series of turbine stages within the turbine section.
  • a turbine stage may include a row of stationary airfoils, i.e., vanes, followed by a row of rotating airfoils, i.e., turbine blades, where the turbine blades extract energy from the hot combustion gases for providing output power.
  • a turbine blade is formed from a root at one end, and an elongated portion forming an airfoil that extends outwardly from a platform coupled to the root.
  • the airfoil comprises a tip at a radially outward end, a leading edge, and a trailing edge.
  • the tip of a turbine blade often has a tip feature to reduce the size of the gap between ring segments and blades in the gas path of the turbine to prevent tip flow leakage, which reduces the amount of torque generated by the turbine blades.
  • the tip features are often referred to as squealer tips and are frequently incorporated onto the tips of blades to help reduce pressure losses between turbine stages. These features are designed to minimize the leakage between the blade tip and the ring segment.
  • aspects of the present invention provide a turbine blade with an improved squealer tip design.
  • a turbine blade comprising an airfoil comprising an outer wall formed by a pressure sidewall and a suction sidewall joined at a leading edge and at a trailing edge.
  • the blade further comprises a blade tip at a first radial end and a root at a second radial end opposite the first radial end for supporting the blade and for coupling the blade to a disc.
  • the blade tip comprises a tip cap disposed over the outer wall of the airfoil, and at least one squealer tip wall extending radially outward of the tip cap and extending along a chord-wise direction of the airfoil.
  • the at least one squealer tip wall comprises laterally opposed first and second side faces.
  • first and second side faces of the at least one squealer tip wall are oriented at respective angles which vary independently along the chord-wise direction, such that the chord-wise variation of a first angle between the first side face and the radial axis is different from the chord-wise variation of a second angle between the second side face and the radial axis.
  • a turbine blade comprising an airfoil comprising an outer wall formed by a pressure sidewall and a suction sidewall joined at a leading edge and at a trailing edge.
  • the blade further comprises a blade tip at a first radial end and a root at a second radial end opposite the first radial end for supporting the blade and for coupling the blade to a disc.
  • the blade tip comprises a tip cap disposed over the outer wall of the airfoil and a pair of squealer tip walls extending radially outward of tip cap and extending along a chord-wise direction of the airfoil.
  • the pair of squealer tip walls includes a pressure side squealer tip wall and a suction side squealer tip wall, wherein a tip cavity is located between the pressure side squealer tip wall and the suction side squealer tip wall.
  • Each squealer tip wall comprises an inner side face facing the tip cavity and an outer side face laterally opposite to the inner side face.
  • the inner side face and the outer side face are oriented at respective angles in relation to a radial axis which vary independently along the chord-wise direction, such that the chord-wise variation of an inner angle between the inner side face and the radial axis is different from the chord-wise variation of an outer angle between the outer side face and the radial axis.
  • FIG. 1 is a perspective view of a turbine blade with a known type of squealer tip
  • FIG. 2 is a schematic cross-sectional view along the section II-II of FIG. 1 ;
  • FIG. 3 is a perspective view of a portion of a turbine blade with a squealer tip according to one embodiment of the present invention
  • FIG. 4, FIG. 5 and FIG. 6 are schematic cross-sectional views along the sections IV-IV, V-V and VI- VI respectively of FIG. 3, illustrating a chord -wise variation of inclination of the inner and outer side faces of the squealer tip walls of the squealer tip; and
  • FIG. 7 is a schematic view of an alternate embodiment of the present invention involving stepped squealer geometry.
  • FIG. 1 illustrates a turbine blade 1.
  • the blade 1 includes a generally hollow airfoil 10 that extends radially outwardly from a blade platform 6 and into a stream of a hot gas path fluid.
  • a root 8 extends radially inward from the platform 6 and may comprise, for example, a conventional fir-tree shape for coupling the blade 1 to a rotor disc (not shown).
  • the airfoil 10 comprises an outer wall 12 which is formed of a generally concave pressure sidewall 14 and a generally convex suction sidewall 16 joined together at a leading edge 18 and at a trailing edge 20, defining a camber line 29.
  • the airfoil 10 extends from the root 8 at a radially inner end to a tip 30 at a radially outer end, and may take any configuration suitable for extracting energy from the hot gas stream and causing rotation of the rotor disc.
  • the interior of the hollow airfoil 10 may comprise at least one internal cavity 28 defined between an inner surface 14a of the pressure sidewall 14 and an inner surface 16a of the suction sidewall 16, to form an internal cooling system for the turbine blade 1.
  • the internal cooling system may receive a coolant, such as air diverted from a compressor section (not shown), which may enter the internal cavity 28 via coolant supply passages typically provided in the blade root 8.
  • the coolant may flow in a generally radial direction, absorbing heat from the inner surfaces 14a, 16a of the pressure and suction sidewalls 14, 16, before being discharged via external orifices 17, 19, 37, 38 into the hot gas path.
  • the tip 30 may be formed as a so-called "squealer tip”.
  • the blade tip 30 may be formed of a tip cap 32 disposed over the outer wall 12 at the radially outer end of the outer wall 12, and at least one squealer tip wall extending radially outward from the tip cap 32.
  • a pair of squealer tip walls 34, 36 are provided, including a pressure side squealer tip wall 34 and a suction side squealer tip wall 36.
  • the pressure and suction side squealer tip walls 34 and 36 may extend substantially or entirely along the perimeter of the tip cap 32 to define a tip cavity 35 between an inner surface 34a of the pressure side squealer tip wall 34 and an inner surface 36a of the suction side squealer tip wall 36.
  • An outer surface 34b of the pressure side squealer tip wall 34 may be aligned with an outer surface 14b of the pressure sidewall 14, while an outer surface 36b of the suction side squealer tip wall 36 may be aligned with an outer surface 16b of the suction sidewall 16.
  • the blade tip 30 may additionally include a plurality of cooling holes 37, 38 that fluidically connect the internal cavity 28 with an external surface of the blade tip 30 exposed to the hot gas path fluid.
  • cooling holes 37 are formed through the pressure side squealer tip wall 34 while the cooling holes 38 are formed through the tip cap 32 opening into the tip cavity 35. Additionally or alternately, cooling holes may be provided at other locations at the blade tip 30.
  • pressure differences between the pressure side and the suction side of the turbine blade 1 may drive a leakage flow F L from the pressure side to the suction side through the clearance between the rotating blade tip 30 and the surrounding stationary turbine component (not shown).
  • the leakage flow F L may lead to a reduction in efficiency of the turbine rotor.
  • the tip leakage flow F L exerts no work on the blade, thus reducing the power generated; second, the tip leakage flow F L may mix with the main flow F M of the gas path fluid (which is generally along an axial direction) as it exits the clearance gap, rolling up into a vortical structure V (see FIG. 2).
  • the vortical structure V referred to as tip leakage vortex, results in a pressure loss and a further reduction in rotor efficiency.
  • Configuring the tip of the blade as a squealer with one or more squealer tip walls 34, 36 may mitigate some of the issues related to tip leakage flow.
  • the squealer tip walls 34, 36 have a rectangular cross-section, as shown in FIG. 2, wherein the laterally opposed side faces of the squealer tip walls are essentially parallel to each other.
  • Embodiments of the present invention are aimed at further improving tip leakage losses by providing a novel squealer geometry incorporating squealer tip walls with variably inclined inner and outer side faces.
  • FIG. 3-6 illustrate an exemplary embodiment of the present invention.
  • the exemplary blade tip 30 comprises a tip cap 32 disposed over the outer wall 12, and at least one squealer tip wall, in this case, a pair of squealer tip walls 34, 36 which are configured as winglets.
  • the tips walls or winglets 34, 36 include a pressure side squealer tip wall or winglet 34 and a suction side squealer tip wall or winglet 36, each extending radially outward of the tip cap 32 and extending along a chord-wise direction of the airfoil 10.
  • a tip cavity 35 is located between the pressure side squealer tip wall 34 and the suction side squealer tip wall 36.
  • the pressure side squealer tip wall or winglet 34 comprises an inner side face 34a facing the tip cavity 35 and an outer side face 34b laterally opposite to the inner side face 34a, the lateral direction being defined from the pressure side to the suction side.
  • the inner side face 34a and the outer side face 34b are oriented at respective angles in relation to a radial axis 40, which vary independently along the chord-wise direction.
  • the cross-sectional views in FIG. 4-6 are taken at different chord-wise locations.
  • chord-wise variation of an inner angle a 34 between the inner side face 34a and the radial axis 40 is different from the chord-wise variation of an outer angle ⁇ 34 between the outer side face 34b and the radial axis 40. Consequently, the angle between the inner and outer side faces 34a, 34b varies in the chord-wise direction.
  • a chord-wise variation of the inclination of the side faces may be provided for the suction side squealer tip wall 36.
  • the suction side squealer tip wall or winglet 36 comprises an inner side face 36a facing the tip cavity 35 and an outer side face 36b laterally opposite to the inner side face 36a.
  • the inner side face 36a and the outer side face 36b are oriented at respective angles in relation to a radial axis 40, which vary independently along the chord-wise direction.
  • chord-wise variation of an inner angle a 36 between the inner side face 36a and the radial axis 40 is different from the chord- wise variation of an outer angle ⁇ 36 between the outer side face 36b and the radial axis 40. Consequently, the angle between the inner and outer side faces 36a, 36b varies in the chord- wise direction.
  • the present inventors have recognized that by increasing the tip inclination in areas of high leakage flow, the flow is redirected away the blade, creating a blockage in the tip region which reduces the mass of leakage flow.
  • the inventors also recognized, however, that it is not necessary or effective to maintain this inclination over the entire extent of the squealer tip. Accordingly, introducing a chord-wise variation in the tip shape along with independent variation in the inner and outer side face inclination angles allows for a more efficient blade tip design.
  • the blade tip 30 may be provided with a step feature adjoining the tip cavity 35.
  • the step feature may include a radially outward step 64, 66 located respectively at either or both of the pressure side edge 44 and the suction side edge 46 of the tip cap 32.
  • the winglets respectively the pressure side squealer tip wall 34 and the suction side squealer tip wall 36 may be disposed on the steps 64, 66, extending radially outward of the tip cap 32.
  • the steps 64, 66 may extend chord-wise direction along a portion or the entire chord-wise extent of the winglets 34, 36.
  • the first 34a, 36a and second 34b, 36b side faces of the winglets 34, 36 are oriented at respective angles which vary independently along the chord-wise direction.
  • the chord-wise variation of a first angle a 34 , a 36 between the first side face 34a, 36a and the radial axis 40 is different from the chord-wise variation of a second angle ⁇ 34 , ⁇ 36 between the second side face 34b, 36b and the radial axis 40.
  • the steps 64, 66 may be provided with film cooling channels (not shown).
  • the chord-wise variation of the tip shape may result in a chord-wise variation of the thickness t 34 , t 36 of the squealer tip walls 34, 36 at the radial ends thereof, as shown in FIG. 4-6 and FIG. 7.
  • a larger angle of inclination/ squealer tip wall thickness may be provided in regions where a high tip leakage flow has been identified.
  • the chord-wise varying inclination of the inner and outer side faces is provided along the entire axial length (from the leading edge to the trailing edge) of both the pressure side squealer tip wall 34 and the suction side squealer tip wall.
  • such a variable inclination of the inner and outer side faces may be provided only for a designated portion extending partially along the axial length of one or both of the squealer tip walls 34, 36.
  • the inner angles a 34 , 36 and the outer ⁇ 3 , ⁇ 36 may independently vary from about - 45 degrees to about + 75 degrees along the chord- wise direction.
  • an inclination of any squealer tip wall side face 34a-b. 36a-b away from the tip cavity 35 (outward in a direction away from the blade) is referenced as a positive angle
  • an inclination toward the tip cavity 35 inward toward the camber line
  • the precise geometry of the squealer tip walls 34, 36, including the inclination angles, and/or chord-wise/axial extent of the variation may be determined based on a number of factors, including for example, size of the tip gap, inlet flow conditions (e.g., Mach number), size of the airfoil, among others.
  • An optimized tip shape reduces leakage mass flow over the tip surface, which, in turn, reduces pressure loss and strength of the tip leakage vortex, thus increasing rotor efficiency.
  • a blade tip 30 with two squealer tip walls depict a blade tip 30 with two squealer tip walls, namely a pressure side squealer tip wall 34 and a suction side squealer tip wall 36 having chord-wise variably inclined side faces
  • aspects of the present invention may apply to a squealer tip design with only one squealer tip wall.
  • only a pressure side squealer tip wall 34 may be provided in accordance with embodiments of the present invention, while suction side squealer tip wall 36 may be omitted, and optionally, replaced at least partially by other tip leakage control features.
  • the blade tip 30 may also comprise cooling holes or channels provided in one or both of the squealer tip walls 34, 36, which are in fluid communication with an internal cooling system within the airfoil.
  • the illustrated blade tip shaping may make efficient use of the cooling flow by controlling the trajectory of the tip leakage flow. Simultaneous optimization of the tip shape and the cooling hole/channel location may thus make use of the change of tip flow trajectory to cool the blade tip, allowing reduced cooling flow, improved engine efficiency and increased component lifetime.
  • the illustrated embodiments of the squealer tip may be adapted to redirect leakage flow and mitigate leakage losses, as well as enhance the heat transfer performance for a given engine application.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)

Abstract

Dans la présente invention, une extrémité d'aube (30) pour une aube de turbine (1) comprend un capuchon de pointe (32) disposé sur une paroi externe de profil aérodynamique (12) et au moins une paroi à bout aminci (34, 36) s'étendant radialement vers l'extérieur du capuchon de pointe (32) et s'étendant le long d'une direction de corde du profil aérodynamique (10). L'au moins un paroi à bout aminci (34, 36) comprennent des première (34a, 36a) et seconde (34b, 36b) faces latérales. Par rapport à un axe radial (40), les première (34a, 36a) et seconde (34b, 36b) faces latérales de l'au moins un paroi à bout aminci (34, 36) sont orientées selon des angles respectifs qui varient indépendamment le long de la direction de corde. Ainsi, la variation dans le sens de la corde d'un premier angle (α34, α36) entre la première face latérale (34a, 36a) et l'axe radial (40) est différente de la variation dans le sens de la corde d'un second angle (β34, β36) entre la seconde face latérale (34b, 36b) et l'axe radial (40).
PCT/US2017/046686 2017-08-14 2017-08-14 Aubes de turbine WO2019035800A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US2017/046686 WO2019035800A1 (fr) 2017-08-14 2017-08-14 Aubes de turbine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US2017/046686 WO2019035800A1 (fr) 2017-08-14 2017-08-14 Aubes de turbine

Publications (1)

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WO2019035800A1 true WO2019035800A1 (fr) 2019-02-21

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11149265B2 (en) 2017-09-14 2021-10-19 California Institute Of Technology Purification and detection of analytes

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1895099A2 (fr) * 2006-08-21 2008-03-05 General Electric Company Aube avec nervures en forme de cascade sur l'extrémité de l'aube
EP1898052A2 (fr) * 2006-08-21 2008-03-12 General Electric Company Extrémité évasée d'aube de turbine
EP1911934A1 (fr) * 2006-10-13 2008-04-16 Snecma Aube mobile de turbomachine
EP2148042A2 (fr) * 2008-07-24 2010-01-27 Rolls-Royce plc Pale de rotor avec l'extrémité partiellement oblique
EP2479382A1 (fr) * 2011-01-20 2012-07-25 Rolls-Royce plc Pale de rotor
DE102012021400A1 (de) * 2012-10-31 2014-04-30 Rolls-Royce Deutschland Ltd & Co Kg Turbinenrotorschaufel einer Gasturbine
EP2725194A1 (fr) * 2012-10-26 2014-04-30 Rolls-Royce Deutschland Ltd & Co KG Aube de rotor d'une turbine à gaz
EP3179038A1 (fr) * 2015-12-11 2017-06-14 General Electric Company Procédé et système d'amélioration des performances de pales de turbine

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1895099A2 (fr) * 2006-08-21 2008-03-05 General Electric Company Aube avec nervures en forme de cascade sur l'extrémité de l'aube
EP1898052A2 (fr) * 2006-08-21 2008-03-12 General Electric Company Extrémité évasée d'aube de turbine
EP1911934A1 (fr) * 2006-10-13 2008-04-16 Snecma Aube mobile de turbomachine
EP2148042A2 (fr) * 2008-07-24 2010-01-27 Rolls-Royce plc Pale de rotor avec l'extrémité partiellement oblique
EP2479382A1 (fr) * 2011-01-20 2012-07-25 Rolls-Royce plc Pale de rotor
EP2725194A1 (fr) * 2012-10-26 2014-04-30 Rolls-Royce Deutschland Ltd & Co KG Aube de rotor d'une turbine à gaz
DE102012021400A1 (de) * 2012-10-31 2014-04-30 Rolls-Royce Deutschland Ltd & Co Kg Turbinenrotorschaufel einer Gasturbine
EP3179038A1 (fr) * 2015-12-11 2017-06-14 General Electric Company Procédé et système d'amélioration des performances de pales de turbine

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11149265B2 (en) 2017-09-14 2021-10-19 California Institute Of Technology Purification and detection of analytes

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