EP2292897A1 - Axialdurchflussturbine - Google Patents

Axialdurchflussturbine Download PDF

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Publication number
EP2292897A1
EP2292897A1 EP09169234A EP09169234A EP2292897A1 EP 2292897 A1 EP2292897 A1 EP 2292897A1 EP 09169234 A EP09169234 A EP 09169234A EP 09169234 A EP09169234 A EP 09169234A EP 2292897 A1 EP2292897 A1 EP 2292897A1
Authority
EP
European Patent Office
Prior art keywords
shroud
radial
cavity
fin
downstream
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.)
Withdrawn
Application number
EP09169234A
Other languages
English (en)
French (fr)
Inventor
Brian Robert Haller
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 EP09169234A priority Critical patent/EP2292897A1/de
Publication of EP2292897A1 publication Critical patent/EP2292897A1/de
Withdrawn legal-status Critical Current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
    • F01D5/145—Means for influencing boundary layers or secondary circulations
    • 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
    • F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
    • F01D11/08—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2240/00—Components
    • F05D2240/10—Stators
    • F05D2240/12—Fluid guiding means, e.g. vanes
    • F05D2240/126—Baffles or ribs
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2270/00—Control
    • F05D2270/01—Purpose of the control system
    • F05D2270/17—Purpose of the control system to control boundary layer

Definitions

  • the disclosure relates generally to axial flow turbines of the type that use a compressible working fluid, such as steam and gas turbines and specifically to the aerodynamic environment within shroud cavities in which airfoil shrouds are circumscribed.
  • An axial flow steam or gas turbine typically comprises rotating airfoils attached to a rotor wherein a cavity in the casing of the stator circumscribes the outer periphery of the rotating airfoils. Between the periphery of the rotating airfoils and the stator there typically is a gap through which a working fluid can leak.
  • the leakage represents a loss in turbine efficiency.
  • the leakage over the rotating airfoils is minimised by the fitting of a shroud and the further circumscribing of the shroud by a casing cavity.
  • a seal may be provided between the casing cavity and shroud.
  • Non-rotating airfoils are typically provided in steam and gas turbines. These non-rotating airfoils are fixed at one end to the stator and may have a shroud at another radially distant end, which, like rotating airfoils may also be circumscribed within a cavity. Unlike rotating airfoils, the cavity for a non-rotating airfoil is typically formed in the rotor. The gap formed between the shroud and hub suffers similar leakage losses to that of rotating airfoils and so is typically also provided with a seal.
  • both types of airfoils when fitted with shrouds share the same problem of leakage flow flowing across their shrouds resulting in secondary flow as the leakage flow rejoins the main flow. This loss is exacerbated by the size and shape of an end cavity through which the leakage flow flows in order to reach the main flow.
  • the end cavity which is part of the cavity formed by the downstream end of the cavity and the shroud, is sized to accommodate axial expansion of the rotor during operation.
  • One method of reducing the turbulence created by this end cavity is to angle the end wall of the cavity from the radial direction towards the downstream flow direction. While such an arrangement can have a positive influence on turbulence such angulation requires additional axial space that can negatively impact the axial machine length, and/or axial distance between axially neighbouring airfoils.
  • a means is provided to reduce secondary flow losses caused by shroud leakage flow as it re-enters the main flow stream via an end cavity that forms part of a shroud cavity circumscribing the shroud. This is achieved without increasing overall turbine length.
  • An aspect provides an axial flow turbine comprising a rotor, a row of circumferentially distributed airfoils, a shroud and a stator.
  • the airfoils extend radially from the rotor across a flow passage end and have, at a radial distal end, a shroud having a downstream end.
  • the stator has a shroud cavity, circumscribing the shroud that is defined by an upstream radial wall, an axially extending base wall and a downstream radial wall.
  • the shroud cavity further comprises an end cavity that opens out into the flow passage.
  • the downstream end of the shroud, a portion of the base wall and the downstream radial wall define this end cavity.
  • a radial fin Located in the end cavity and disposed on the portion of the base wall is a radial fin.
  • the fin extends circumferentially around the stator and is adapted to deflect, in the direction of the flow passage, leakage flow entering the end cavity from a gap between the shroud and the base wall.
  • An aspect provides an axial flow turbine comprising a rotor, a row of circumferentially distributed airfoils, a shroud and a stator.
  • the airfoils extend radially from the stator across a flow passage end and have, at a radial distal end, a shroud having a downstream end.
  • the rotor has a shroud cavity, circumscribing the shroud that is defined by an upstream radial wall, an axially extending base wall and a downstream radial wall.
  • the shroud cavity further comprises an end cavity that opens out into the flow passage.
  • the downstream end of the shroud, a portion of the base wall and the downstream radial wall define this end cavity.
  • a radial fin Located in the end cavity and disposed on the portion of the base wall is a radial fin.
  • the fin extends circumferentially around the rotor and is adapted to deflect, in the direction of the flow passage, leakage flow entering the end cavity from a gap between the shroud and the base wall.
  • a fin As compared to an insert a fin is more cost effective as it has less metal and further is does not restrict axial movement. That is if the shroud where to axially expand over the fin, damage would be limited to the bending of the fin and as a result would not require the shutting down of the machine for repair. As a result the end cavity axially length can be shortened as its sizing does not need to consider the fin, thus achieving the combined benefit of a shorter length and efficiency gain.
  • lengths may be referred to in terms of the radial or axial dimensions whose direction is measured relative to the rotational axis of the rotor. Further, within this specification these terms are also taken to mean the radial or axial vector component of the length as measured from the end points of the referenced feature, as such, the radial or axial length maybe different to the actual length. For example, the length of a surface, which is curved but has end points that lie in the radial plain has a shorter radial length that actual length. Likewise were angles are described, the reference the angle of a feature is defined by a vector line drawn between the end points of the feature and not the discrete angles along portions of the feature.
  • An exemplary embodiment provides an axial flow steam turbine as shown in FIG. 1 that comprises a rotor 3 on which a row of circumferentially distributed rotating airfoils 5 extend radially into the main steam flow passage 2 of a steam turbine.
  • the direction of flow represented by arrows, defines the relative up and downstream location designations.
  • a shroud 6 circumscribed by a shroud cavity 10.
  • the shroud cavity 10 is formed in the stator 4 by an upstream radial wall 11, an axially extending base wall 12 and a downstream radial wall 14.
  • the downstream end of the shroud 7 with a portion of the base wall 12 and the downstream radial wall 14 forms an end cavity within the shroud cavity 10.
  • the purpose of this end cavity is to provide space for the typical axial expansion of the rotor 3 that results in the axial movement of the shroud 6.
  • the end cavity opens out in the flow passage thus enabling leakage flow to pass through the gap between the shroud 6 and base wall 12 and rejoin the main steam flow.
  • An alternate exemplary embodiment provides an axial flow steam turbine as shown in FIG. 1 that comprises a stator 4 on which a row of circumferentially distributed fixed airfoils 5 extend radially into the main steam flow passage of the steam turbine.
  • the direction of flow represented by arrows, defines the relative up and downstream location designations.
  • a shroud 6 which is circumscribed by a shroud cavity 10 formed in the rotor 3 by an upstream radial wall 11, an axially extending base wall 12 and a downstream radial wall 14.
  • the downstream end of the shroud 7, a portion of the base wall 12 and the downstream radial wall 14 form an end cavity within the shroud cavity 10.
  • the purpose of this end cavity is to provide space for the typical axial expansion of the rotor 3 that results in the axial movement of the shroud 6.
  • the end cavity opens out in the flow passage thus enabling leakage flow to pass through the gap between the shroud 6 and base wall 12 to reunite with the main steam flow.
  • Both these exemplary embodiments provide a circumferentially extending radial fin 20 in the end cavity that is disposed on a downstream portion of the base wall 12.
  • the purpose of the fin 20 is to direction leakage flow that enters the end cavity from a gap between the shroud 6 and the base wall 12 back into the main passage flow in a way that secondary flow losses are reduced. This can be achieved by adapting the axial length of the fin 20.
  • a fin 20 is differentiated from a block or insert by having only one point of contact with the end cavity i.e. the base wall 12 and further by a large length to width ratio.
  • a fin 20 depending on the materials it is made of, is inherently flexible. Therefore, if for example, a shroud 6 was to come in contact with a fin 20 for a short period of time, the fin 20 may flex or blend and as a result damage to both the shroud and fin 20 will be minimised.
  • the size of the end cavity does not need to consider the fin 20 unlike the case were inherently inflexible blocks and inserts are used in the end cavity for the purpose of reducing secondary losses.
  • a fin 20 can be retrofitted to existing designs more easily than blocks and inserts and further due to their lower material weight are cheaper to manufacture.
  • a fin 20 is inherently flexible, by adapting the radial length of the fin 21, contact between the shroud 6 and the fin 20 can be avoided in all circumstances, eliminating the risk of even slight damage to the fin 20.
  • the shape of the base wall 12, shroud 6 and the gap is typically non-uniform throughout its length. Therefore the radial length of the fin 21, to avoid contact with the shroud 6, must be adapted taking in account of individual turbine configuration. In one exemplary embodiment, this is achieved by configuring the fin 20 to have a radial length 21 less than the radial width 16 of the gap between the downstream end of the shroud 7 and the base wall 12.
  • the gap in this specification, is defined as the radial gap at the downstream end of the shroud not including fins or other seal elements that are typically mounted on the shroud 6 and/or the corresponding base wall 12.
  • the fin 20 may be angled ⁇ from the radial in the downstream axial direction by greater than 0°. If the fin 20 is angled too far the negative benefit of turbulence created by the fin 20 may be greater than the benefit of the flow deflection. Therefore, in an exemplary embodiment, the fin 20 is angled no more than about 30°.
  • the fin 20 extends from a point located more than 30% along the axial length of the end cavity base wall portion 13, as taken in the flow direction.
  • the fin 20 extends from a point located less than 60% along the axial length of the end cavity base wall portion 13 as taken in the flow direction.
  • the fin 20 is provided in an end cavity in which the radial length of the downstream radial wall 14 is between 0.5 and 3 times the axial length of the end cavity base wall portion 13.
  • the downstream radial wall 14 is angled ⁇ in the downstream direction by less than 10° from the radial.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
EP09169234A 2009-09-02 2009-09-02 Axialdurchflussturbine Withdrawn EP2292897A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP09169234A EP2292897A1 (de) 2009-09-02 2009-09-02 Axialdurchflussturbine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP09169234A EP2292897A1 (de) 2009-09-02 2009-09-02 Axialdurchflussturbine

Publications (1)

Publication Number Publication Date
EP2292897A1 true EP2292897A1 (de) 2011-03-09

Family

ID=41786156

Family Applications (1)

Application Number Title Priority Date Filing Date
EP09169234A Withdrawn EP2292897A1 (de) 2009-09-02 2009-09-02 Axialdurchflussturbine

Country Status (1)

Country Link
EP (1) EP2292897A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018230411A1 (ja) * 2017-06-12 2018-12-20 三菱日立パワーシステムズ株式会社 軸流回転機械

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2179556A (en) * 1933-03-08 1939-11-14 Milo Ab Method of making turbines
EP1001138A1 (de) * 1998-11-10 2000-05-17 Asea Brown Boveri AG Spitzendichtung für Turbinenlaufschaufeln
JP2004011553A (ja) * 2002-06-07 2004-01-15 Mitsubishi Heavy Ind Ltd 軸流型ターボ機械
JP2007321721A (ja) * 2006-06-05 2007-12-13 Toshiba Corp 軸流タービン段落および軸流タービン
US20090047120A1 (en) * 2007-08-10 2009-02-19 Volker Guemmer Blade shroud with fluid barrier jet generation
JP2009047043A (ja) * 2007-08-17 2009-03-05 Mitsubishi Heavy Ind Ltd 軸流タービン
EP2096262A1 (de) * 2008-02-26 2009-09-02 Siemens Aktiengesellschaft Axialturbine mit geringen Leckageverlusten

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2179556A (en) * 1933-03-08 1939-11-14 Milo Ab Method of making turbines
EP1001138A1 (de) * 1998-11-10 2000-05-17 Asea Brown Boveri AG Spitzendichtung für Turbinenlaufschaufeln
JP2004011553A (ja) * 2002-06-07 2004-01-15 Mitsubishi Heavy Ind Ltd 軸流型ターボ機械
JP2007321721A (ja) * 2006-06-05 2007-12-13 Toshiba Corp 軸流タービン段落および軸流タービン
US20090047120A1 (en) * 2007-08-10 2009-02-19 Volker Guemmer Blade shroud with fluid barrier jet generation
JP2009047043A (ja) * 2007-08-17 2009-03-05 Mitsubishi Heavy Ind Ltd 軸流タービン
EP2096262A1 (de) * 2008-02-26 2009-09-02 Siemens Aktiengesellschaft Axialturbine mit geringen Leckageverlusten

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018230411A1 (ja) * 2017-06-12 2018-12-20 三菱日立パワーシステムズ株式会社 軸流回転機械
CN110662885A (zh) * 2017-06-12 2020-01-07 三菱日立电力系统株式会社 轴流旋转机械
KR20200002988A (ko) * 2017-06-12 2020-01-08 미츠비시 히타치 파워 시스템즈 가부시키가이샤 축류 회전 기계
JPWO2018230411A1 (ja) * 2017-06-12 2020-03-26 三菱日立パワーシステムズ株式会社 軸流回転機械
US11053807B2 (en) 2017-06-12 2021-07-06 Mitsubishi Power, Ltd. Axial flow rotating machine
CN110662885B (zh) * 2017-06-12 2022-04-01 三菱动力株式会社 轴流旋转机械

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