EP1612372B1 - Aube de turbine avec une partie decoupée au pied de l'aube - Google Patents

Aube de turbine avec une partie decoupée au pied de l'aube Download PDF

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Publication number
EP1612372B1
EP1612372B1 EP20040103117 EP04103117A EP1612372B1 EP 1612372 B1 EP1612372 B1 EP 1612372B1 EP 20040103117 EP20040103117 EP 20040103117 EP 04103117 A EP04103117 A EP 04103117A EP 1612372 B1 EP1612372 B1 EP 1612372B1
Authority
EP
European Patent Office
Prior art keywords
blade
region
cut
platform
turbine
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
EP20040103117
Other languages
German (de)
English (en)
Other versions
EP1612372A1 (fr
Inventor
Ralf Dr. Greim
Said Dr. Havakechian
Ivan Mcbean
Simon-Pierre Monette
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Technology GmbH
Original Assignee
Alstom Technology AG
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 Alstom Technology AG filed Critical Alstom Technology AG
Priority to EP20040103117 priority Critical patent/EP1612372B1/fr
Publication of EP1612372A1 publication Critical patent/EP1612372A1/fr
Application granted granted Critical
Publication of EP1612372B1 publication Critical patent/EP1612372B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • F01D5/141—Shape, i.e. outer, aerodynamic form
    • F01D5/142—Shape, i.e. outer, aerodynamic form of the blades of successive rotor or stator blade-rows
    • F01D5/143—Contour of the outer or inner working fluid flow path wall, i.e. shroud or hub contour
    • 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
    • F01D5/141—Shape, i.e. outer, aerodynamic form
    • 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
    • F01D5/141—Shape, i.e. outer, aerodynamic form
    • F01D5/145—Means for influencing boundary layers or secondary circulations

Definitions

  • the invention pertains to a turbine blade and in particular to a three-dimensional shape of the end-regions of the blade.
  • Turbine blades having a suction and pressure side and extending from a hub to a tip and from a leading edge to a trailing edge.
  • a chord extends essentially from the leading edge to the trailing edge of the blade.
  • the blades are integrally machined with blade platforms, typically of a rhombus shape, for mounting on a rotor.
  • the flow of a working medium through a turbine may be described having a core flow in the mid-region between the tip and hub of the blade and flow layers near the end-wall regions. Near the end-wall regions, an inlet boundary layer of the flow rolls about the leading edge of the blades giving rise to horse shoe like vortices flowing along both the pressure as well as the suction side of the blade. Traverse pressure gradients between the pressure side of blades in a given blade row and the suction side of blades in an adjacent blade row act together with radial pressure gradients on the horse shoe vortices and cause complex three-dimensional flow patterns, also known as secondary flows. These constitute a significant portion of the overall losses encountered in turbine stages of low aspect ratio (ratio of longitudinal blade length to chord length).
  • a decrease of the chord length near the end-walls can be realised by cutting back the blade profile at the trailing edge and effectively shortening the axial extent of the blade in the end-wall regions.
  • a decreased chord length triggers a faster expansion of the end-wall flow, creating a radial pressure gradient such that the penetration of the secondary vortex flow into the main flow in the mid-region of the blade is reduced.
  • EP 798447 discloses a blade having a cut back in an end-region of its trailing edge for example in the tip region of a vane as shown in its figure 2c .
  • the blade comprises in addition, a twist of the trailing edge about the leading edge, as demonstrated by stacking angles ⁇ for the profiles shown in its figure 2d.
  • the stacking angle for the profile at the blade tip (P' R ) is greater than that for the profile away from the tip (P' M ), which effects an opening of the throat of the blade row.
  • the blade has no lean, as manifested by the straight leading edge shown in its figure 3a.
  • a turbine blade rotating or stationary, extends from a platform to a tip and comprises a pressure side and suction side, a leading edge and a trailing edge.
  • a chord extends between the leading and trailing edge essentially parallel to the platform.
  • the blade is considered to have end-regions near the platform and near the tip with a mid region extending radially between the two end regions.
  • the trailing edge in the end-region near the platform is shaped having a cut-back relative to the mid-region of the trailing edge.
  • the blade comprises a twist of the blade in the end-region near the platform with the cutback in combination with a lean of the end-region with the cut-back. The lean is directed perpendicular to the chord and such that the pressure side points toward the platform of the blade.
  • a cut-back of a blade trailing edge alone would cause an increased throat and flow angle of the blading, which in turn would cause a reduction of the expansion or pressure drop near the endwall.
  • a cut-back alone furthermore effects an increase in the loading of the end-region, as already mentioned. Also, a smaller chord length results in an increased pitch to chord ratio, which leads to a load increase.
  • the blade In order to correct for the increase of throat and exit angle, the blade is twisted in the region of the cut-back. This effectively produces a closing of the throat. Throat and flow angle are again restored to their original values without cut-back and the original amount of expansion is restored as well.
  • twisting of the blade results in that the profile section at the platform extends locally outside of the rhombus-shaped blade platform resulting in an overhang of the blade over the edge of the platform.
  • the lean according to the invention corrects for both the increased loading and the profile section overhang outside the platform.
  • the lean of the blade perpendicular to the chord direction effectively produces a higher pressure zone near the end walls, which leads to a reduction of the load in the end-regions to levels comparable to a blade without cut-back.
  • the lean is realised by a translation of the end-region, which brings back the overhang portion of the blade to within the extent of the blade platform. It is predominantly in the cut-back end-region.
  • the amount of lean is determined by the initial amount of cut-back and amount of twist necessary for the closing of the throat.
  • the extent of the cut-back is determined according to the aspect ratio of blade length to chord length. As such, its extent varies according to the type and size of blades in the turbine.
  • the blade design according to the invention is equally applicable to both rotating as well as stationary blades.
  • Figure 1 shows in a side view a rotating turbine blade 1. It extends from a leading edge 4 to a trailing edge 5 and from a hub 2 to a tip 3 essentially in the radial direction with respect to the turbine rotor.
  • the blade is mounted on the rotor by means of a blade platform 6, which is an integral part of the blade. It comprises a blade shroud 7 at its tip 3 and end-regions 8a and 8b near the platform and tip respectively, as well as a mid-region 9 between the end-regions.
  • the radial extent of the regions 8a, 8b, and 9 vary according to the size of the blade and stage position within the turbine.
  • the blade according to the invention has the primary feature of a cut-back 10 of the trailing edge 5 in its end-region.
  • the shown embodiment has a cut-back only in the end-region 8b near the hub 2 and platform 6.
  • the blade with a cut-back has a reduced chord-length in the end-region near the hub compared to a blade without cut-back.
  • the cut-back b extends over a length a in the longitudinal direction of the blade.
  • the longitudinal extent a of the cut-back is chosen according to the aspect ratio of blade length l to chord length s, which can vary for example within a range from 0.5 to 6. In general, the smaller the aspect ratio of a blade, the greater is the effect of secondary vortex-flows.
  • the extent a of the cut-back is in the range between 0 and 40% of the length l of the blade, where the smaller the aspect ratio, the greater the extent a of the cut-back.
  • Figure 2a ), b) and c) illustrate the steps of the blade design according to the invention. For purposes of illustration, all design steps are shown in exaggerated manner.
  • Figure 2a shows cross-sectional profiles of two adjacent blades in a blade row. T indicates the tangential direction of the turbine rotor. The figure shows for each blade three profiles at the cross-section along II-II in figure 1 and at two further levels parallel to II-II and within the end-region 8b between the line II-II and the platform 6.
  • Profile 21 represents a profile in the mid-region 9 of the blade having no cut-back, while the profiles 22 and 23 represent blade profiles at different levels within the end-region with progressing cut-back and with a progressively shorter chord-length s.
  • the profile 23 is at the radial level closest to the blade platform and has the largest b of cut-back. As a result of the cut-back, the throat t' between profiles 23 of the adjacent blades is increased compared to the throat t between profiles 21. The exit angle of the blades is increased as well.
  • Figure 2b shows a twisting of the cross-sectional profiles of the end-region 8b relative to one another by means of a rotation of the cross-sectional blade profiles of figure 2a .
  • the cross-sectional profiles are rotated in such a way that the trailing edge of the blade is turned in a direction toward the suction side 30 of an adjacent blade in the blade row and as a result the throat is closed or decreased.
  • the blade profiles 24, 25, 26 are rotated about a point at or near the leading edge 4, while the cross-sectional blade profiles of the mid-region are left unchanged.
  • the cross-sectional profiles could also be rotated about any other point, for example about their center of gravity.
  • the twist is realized by rotation of blade profiles about a point on the leading edge or other point such as centre of gravity.
  • Profiles 21 and 23 are again shown as reference.
  • Profiles 24, 25, 26 show the progressive twist of the blade, profile 26 being the profile closest to the platform 6 and rotated the most. The twist effects a "closing” or decrease of the throat from throat t' between cross-sectional profiles 23 to throat t" between cross-sectional profiles 26.
  • the arrow “C” indicates the direction of the "closing" the throat.
  • the twist of the blade end-region results in an overhang of the blade profiles close to the blade platform over the edge of the platform 6.
  • the blade end-region is leaned toward the platform according to the invention as shown in figure 2c .
  • Profile 28 closest to the platform is translated the most with respect to the mid-region and lies within the extent of the blade platform.
  • the amount of necessary translation is determined by the geometry of the platform and aerodynamic considerations.
  • the lean is preferably along the direction perpendicular to the chord. However, it can also be along other directions, for example the tangential direction, as long as the resultant blade profile is within the blade platform.
  • the complete blade design comprises cross-sectional profiles stacked in the longitudinal direction. Beginning at the cross-sectional level where the cut-back begins (cross-section 21) and moving in the radial direction toward the blade platform, the cross-sectional profiles have a progressing combination of cut-back, twist and lean, ending with cross-section 28.
  • Figure 3 shows a perspective view of the blade 1 with a trailing edge cutback in the end-region 8b near the platform 6, a twist of the end-region with respect to the mid-region 9 of the blade, and the lean 31 of the pressure side 32 toward the platform 6 along the line perpendicular to the chord. The lean 31 is most evident along the leading edge 4 in the end-region near the platform 6.
  • blade according to the invention have a cut-back in the end-region near the tip, or at both end-regions.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)

Claims (4)

  1. Aube de turbine (1) située dans une rangée d'aubes, l'aube de turbine ayant un côté de pression et un côté d'aspiration (30) s'étendant entre un bord d'attaque (4) et un bord de fuite (5) et d'une plateforme d'aube (6) jusqu'à un bout d'aube (3), l'aube (1) comprenant une première région d'extrémité (8a) située à proximité du bout d'aube (3), une seconde région d'extrémité (8b) située à proximité de la plateforme d'aube (6) et une région centrale (9) s'étendant entre les première et seconde régions d'extrémité (8a, 8b) et l'aube ayant un cordon (s) s'étendant essentiellement le long d'une ligne droite située entre le bord d' attaque (4) et le bord de fuite (5) et l'aube ayant des profilés (21-28) en section transversale empilés le long d'une direction longitudinale de l'aube, caractérisée en ce que le bord de fuite (5) est formé avec une partie découpée (10) par rapport à la région centrale (9) située dans la seconde région d'extrémité (8b) à proximité de la plateforme d'aube (6), que cette seconde région d'extrémité (8b) a une partie découpée (10) vrillée par rapport à la région centrale (9) de l' aube (1) et dans une direction (C) fermant la gorge de la rangée d'aubes et que la seconde région d'extrémité (8b) située à proximité de la plateforme d'aube (6) et ayant une partie découpée (10) compose un appui (31) par le biais d'une translation des profilés (27-28) en section transversale de la seconde région d'extrémité (8b) située à proximité de la plateforme d'aube (6) par rapport à la région centrale (9) et dans la direction de la plateforme d'aube (6) de telle sorte que le profilé d'aube résultant se place à l'intérieur de l'extension de la plateforme d'aube (6).
  2. Aube de turbine (1) selon la revendication 1, caractérisée en ce que les profilés (27-28) en section transversale de la seconde région d'extrémité (8b) située à proximité de la plateforme d'aube (6) sont translatés dans la direction (C) perpendiculaire au cordon (s) de l'aube (1).
  3. Aube de turbine (1) selon la revendication 1, caractérisée en ce que l'extension (a) de la partie découpée (10) le long de la direction longitudinale de l'aube se situe à l'intérieur de la plage allant de 0 à 40 % de la longueur longitudinale (ℓ) de l'aube (1).
  4. Aube de turbine (1) selon la revendication 1, caractérisée en ce que l'aube (1) est soit une aube pivotante soit une aube stationnaire d'une turbine à gaz ou à vapeur.
EP20040103117 2004-07-01 2004-07-01 Aube de turbine avec une partie decoupée au pied de l'aube Expired - Lifetime EP1612372B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP20040103117 EP1612372B1 (fr) 2004-07-01 2004-07-01 Aube de turbine avec une partie decoupée au pied de l'aube

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP20040103117 EP1612372B1 (fr) 2004-07-01 2004-07-01 Aube de turbine avec une partie decoupée au pied de l'aube

Publications (2)

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EP1612372A1 EP1612372A1 (fr) 2006-01-04
EP1612372B1 true EP1612372B1 (fr) 2014-10-08

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Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4956277B2 (ja) * 2007-05-24 2012-06-20 株式会社東芝 ノズル翼翼列、動翼翼列および軸流タービン
EP2221454A1 (fr) * 2009-02-24 2010-08-25 Alstom Technology Ltd Aube carénée de turbine à gaz
GB201217482D0 (en) * 2012-10-01 2012-11-14 Rolls Royce Plc Aerofoil for axial-flow machine
EP3192970A1 (fr) 2016-01-15 2017-07-19 General Electric Technology GmbH Aube de turbine à gaz et procédé de fabrication
WO2017195782A1 (fr) * 2016-05-09 2017-11-16 三菱重工業株式会社 Pale de stator de turbine et turbine comprenant celle-ci
FR3097262B1 (fr) 2019-06-14 2023-03-31 Safran Aircraft Engines Pi Aji Aube de turbomachine avec talon optimise et procede d’optimisation d’un profil d’aube
US11566530B2 (en) 2019-11-26 2023-01-31 General Electric Company Turbomachine nozzle with an airfoil having a circular trailing edge
US11629599B2 (en) 2019-11-26 2023-04-18 General Electric Company Turbomachine nozzle with an airfoil having a curvilinear trailing edge

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2660401A (en) * 1951-08-07 1953-11-24 Gen Electric Turbine bucket
DE2034890A1 (de) * 1969-07-21 1971-02-04 Rolls Royce Ltd Derby, Derbyshire (Großbritannien) Schaufel fur Axialstromungsmaschinen
US5088892A (en) * 1990-02-07 1992-02-18 United Technologies Corporation Bowed airfoil for the compression section of a rotary machine
US6375419B1 (en) * 1995-06-02 2002-04-23 United Technologies Corporation Flow directing element for a turbine engine
ES2163678T3 (es) * 1996-03-28 2002-02-01 Mtu Aero Engines Gmbh Hoja de paleta para turbinas.
JP2000045704A (ja) * 1998-07-31 2000-02-15 Toshiba Corp 蒸気タービン
JP2002256810A (ja) * 2001-03-05 2002-09-11 Toshiba Corp 軸流タービン

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