CN111259559B - Flow control method for reducing loss by cantilever stator blade front loading design - Google Patents

Flow control method for reducing loss by cantilever stator blade front loading design Download PDF

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CN111259559B
CN111259559B CN202010078012.1A CN202010078012A CN111259559B CN 111259559 B CN111259559 B CN 111259559B CN 202010078012 A CN202010078012 A CN 202010078012A CN 111259559 B CN111259559 B CN 111259559B
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blade
stator blade
design
cantilever
loss
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CN111259559A (en
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居振州
滕金芳
李健
朱铭敏
羌晓青
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Shanghai Jiaotong University
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D19/00—Axial-flow pumps
    • F04D19/02—Multi-stage pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/40—Casings; Connections of working fluid
    • F04D29/52—Casings; Connections of working fluid for axial pumps
    • F04D29/54—Fluid-guiding means, e.g. diffusers
    • F04D29/541—Specially adapted for elastic fluid pumps
    • F04D29/542—Bladed diffusers
    • F04D29/544—Blade shapes
    • 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
    • F05D2220/00—Application
    • F05D2220/30—Application in turbines
    • F05D2220/32—Application in turbines in gas turbines
    • F05D2220/321—Application in turbines in gas turbines for a special turbine stage
    • F05D2220/3216—Application in turbines in gas turbines for a special turbine stage for a special compressor stage
    • F05D2220/3219—Application in turbines in gas turbines for a special turbine stage for a special compressor stage for the last stage of a compressor or a high pressure compressor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

Abstract

A flow control method for reducing loss of a cantilever stator blade front loading design is characterized in that a first-stage compressor model consisting of an embedded third-stage rotor blade and a cantilever stator blade is established and is subjected to grid division, a numerical simulation method is adopted, a Reynolds average NS equation of a design point and a near surge point working condition is solved under an experimental working condition, and a front loading design structure for optimizing the uneven distribution of stator blade loads along chord lengths is obtained through a comparison analysis result. According to the invention, the axial position range of the maximum pressure coefficient difference is determined to be 8% -12%, the change of the blade load from the front edge to the tail edge is effectively controlled, the intensity and the flow loss of the leakage flow are further controlled, and the root loss of the cantilever stator blade at the near surge point is maintained at the design point level.

Description

Flow control method for reducing loss by cantilever stator blade front loading design
Technical Field
The invention relates to the technology in the field of impeller machinery, in particular to a flow control method for reducing loss through a cantilever stator blade front loading design.
Background
The pneumatic development of the axial-flow compressor is a key technology for the research and development of an aero-engine. Stator blades of the axial-flow compressor mainly comprise two types, namely shrouded stator blades and cantilever stator blades. Compared with the shrouded stator blade, the cantilever stator blade has the advantages of simple structure, low weight and short axial clearance. The gap leakage flow of the cantilever stator blade can blow off part of low-energy fluid mass in the root corner region, so that the pneumatic performance of the compressor is improved. However, the leakage flow existing in the blade root clearance interacts with the boundary layer of the blade surface and the hub boundary layer, so that the structure of the flow field of the blade root is very complex, and the flow in the corner region of the root has stronger three-dimension and nonlinearity. The loss of the cantilever stator blade mainly comes from the leakage flow in the clearance, and the loss of the cantilever stator blade can be reduced by effectively controlling the strength and the range of the leakage flow.
At present, an aero-engine is developed to a new level, an axial-flow compressor pays more attention to efficient high-load design, and leakage flow loss of a cantilever stator blade becomes one of main influence factors restricting the performance of the aero-engine. Further study has found that the design point of the cantilever vane at the present stage can maintain a low aerodynamic loss level, and the total pressure loss at the root of the cantilever vane rises linearly at the near surge point. The method has the advantages that the reasonable load control method is adopted for the cantilever stator blade to reduce the aerodynamic loss of the root of the cantilever stator blade at a design point and a near surge point, and the method has important significance for improving the performance of an aircraft engine.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a flow control method for reducing loss by adopting cantilever stator blade front loading design, which effectively controls the change of blade load from the front edge to the tail edge by determining that the axial position range of the maximum pressure coefficient difference is 8-12%, further controls the intensity and the flow loss of leakage flow, and maintains the root loss of the cantilever stator blade at the near surge point at the design point level. A geometric modeling and numerical simulation method is adopted, distribution of aerodynamic parameters in a gap of the root of the cantilever stator blade along the chord direction under the working conditions of a design point and a near surge point is given, a root loss coefficient is determined, a proper front loading design scheme is finally given, and loss reduction in the axial flow compressor is achieved.
The invention is realized by the following technical scheme:
the method comprises the steps of establishing a first-stage compressor model consisting of an embedded third-stage rotor blade and a cantilever stator blade, dividing the first-stage compressor model into grids, solving Reynolds average NS equations of a design point and a near surge point under an experimental working condition by adopting a numerical simulation method, and obtaining a front loading design structure with the stator blade load distributed unevenly along the chord length through comparison and analysis results.
The root of the cantilever stator blade adopts a front loading design.
The primary compressor model comprises a cantilever stator blade model which is assembled in the axial compressor model and is designed by front loading and a rotor blade model which is arranged in front of the axial compressor model.
The grid division refers to: the main flow area of the blade channel adopts O4H grid subareas, H-shaped grids are adopted in radial gaps between the main flow area and the wheel disc, and the height of the first-layer grid is set to be 3 x 10 -6 m。
The solving under the experimental condition is as follows: solving a Reynolds average Navier-Stokes equation by adopting a numerical simulation method:
Figure BDA0002379145440000021
wherein: />
Figure BDA0002379145440000022
Is a conservative parameter vector, is>
Figure BDA0002379145440000023
Figure BDA0002379145440000024
And &>
Figure BDA0002379145440000025
Is respectively a non-viscosity vector flux and a viscosity vector flux and is based on the relative ratio of the viscosity vector to the viscosity vector>
Figure BDA0002379145440000026
Figure BDA0002379145440000027
q i Is a heat source term>
Figure BDA0002379145440000028
τ ij Is stressed and is taken>
Figure BDA0002379145440000029
δ ij Is a Crohn's sign, is asserted>
Figure BDA00023791454400000210
Q is the source term>
Figure BDA00023791454400000211
Figure BDA00023791454400000212
Represents an external force, W f Represents the work done by these external forces>
Figure BDA00023791454400000213
The comparative analysis result refers to that: carrying out different aspects of comparative analysis on a flow field of a blade root, comprising the following steps: and comparing the distribution of the surface pressure coefficient difference, the total pressure loss coefficient and the circumferential leakage momentum along the chord direction of the blade root profile surface of the stator blade to obtain the circumferential leakage momentum taking the key aerodynamic parameter of the leakage loss of the cantilever stator blade root as the unit axial chord length, and adopting a front loading design to effectively control the leakage loss result within 2 percent of the blade height close to the surge point.
The optimized stator blade chord length design structure is as follows: the front loading design is adopted for 8% -12% of chord length.
Technical effects
The invention integrally solves the problem that the loss of the cantilever stator blade is sharply increased at a near surge point.
Compared with the prior art, the method can realize the optimal design of the optimal axial position of the front loading for reducing the loss under the working condition of the cantilever stator blade at the near surge point, obtain the key pneumatic parameters for determining the loss of the root clearance of the cantilever stator blade, provide a parameter control method for reducing the loss of the cantilever stator blade, is simple and effective, and achieve the aim of reducing the pneumatic loss through passive flow control.
Drawings
FIG. 1 is a schematic view of the computational domain of a compressor rotor blade and a forward-loaded designed cantilever stator blade;
FIG. 2 is a graph showing the difference in surface pressure coefficient of a cantilever stator vane at 2% of the vane height;
FIG. 3 is a schematic view of the chordwise distribution of circumferential leakage momentum per axial chord length within the gap at the root of a cantilever stator blade;
FIG. 4 is a graph illustrating a comparison of 2% tip height total pressure loss coefficient and circumferential leakage momentum distribution along the chord direction at the root of a cantilevered stator blade.
Detailed Description
As shown in fig. 1, in the embodiment, a first-stage compressor model composed of an embedded third-stage rotor blade and a cantilever stator blade is established and is subjected to grid division, a numerical simulation method is adopted, the reynolds average Navier-Stokes equation of the working conditions of a design point and a near-surge point is solved under the experimental working condition, and a front loading design structure with the stator blade load distributed unevenly along the chord length is obtained through the comparison and analysis result.
The root gap of the cantilever stator blade is 0.95mm, namely 1.1% of the blade height.
The grid division refers to: the main flow area adopts O4H grid partition, the sealing cavity adopts H-shaped grids, the height of the first layer of grids is set to be 3 x 10 -6 m。
The solving specifically includes: solving a Reynolds average Navier-Stokes equation by adopting a numerical simulation method:
Figure BDA0002379145440000031
wherein: />
Figure BDA0002379145440000032
Is a conservative parameter vector, is>
Figure BDA0002379145440000033
Figure BDA00023791454400000315
And &>
Figure BDA0002379145440000034
Is respectively a non-viscosity vector flux and a viscosity vector flux and is based on the relative ratio of the viscosity vector to the viscosity vector>
Figure BDA0002379145440000035
Figure BDA0002379145440000036
q i Is a heat source term>
Figure BDA0002379145440000037
τ ij Is stressed and is taken>
Figure BDA0002379145440000038
δ ij Is a Crohn's sign, is asserted>
Figure BDA0002379145440000039
Q is the source term>
Figure BDA00023791454400000310
Figure BDA00023791454400000311
Represents an external force, W f Represents the work done by these external forces>
Figure BDA00023791454400000312
As shown in fig. 2, the comparative analysis refers to: the load of the blade root section is measured by the difference of the surface pressure coefficients of the cantilever stator blade with the 2 percent blade height, wherein: coefficient of pressure of blade surface
Figure BDA00023791454400000313
Figure BDA00023791454400000314
For total pressure at the inlet of the blade channel, p in For static pressure at the inlet of the vane passage, p blade Is the blade surface static pressure. Pressure coefficient difference Δ C p ＝C p,ps -C p,ss Subscripts ps and ss denote the pressure side and suction side, respectively.
As can be seen from FIG. 2, at 2% blade height, the blade loads at the design and near-tip-to-tip points gradually increase from the leading edge, followed by a gradual decrease in load. The maximum loading position of the near wheezing point is shifted forward from the 12% chord position to the 8% chord position compared to the design point, and the load of the near wheezing point is lower than the design point after 15% chord.
As shown in FIG. 3, the distribution of leakage flow circumferential momentum in the root gap of the front-loaded design cantilevered stator blade in chordwise direction under two conditions is given, and FIG. 4 shows the total pressure loss coefficient of the cantilevered stator blade at 2% blade height below versus the variation of the circumferential leakage momentum distribution along chordwise direction: cantilever stator blade root clearance internal leakage flow
Figure BDA0002379145440000041
ρ is density, vn is velocity perpendicular to the mean camber line of the blade, c is chord length, and/or>
Figure BDA0002379145440000046
For inlet flow, r is the radius, subscript hub represents blade root position and casting represents hub position. Circumferential leakage momentum based on unit axial chord length in root gap>
Figure BDA0002379145440000042
Figure BDA0002379145440000043
μ t Representing circumferential momentum, vt is circumferential velocity, and subscript in is the inlet parameter. Total pressure loss coefficient->
Figure BDA0002379145440000047
Figure BDA0002379145440000048
Total pressure at the inlet of the blade channel, p * The total pressure of the channels at different blade heights is the local pressure. The circumferential leakage momentum of the unit axial chord length is taken as an important parameter for judging the leakage loss of the root part of the cantilever stator blade.
As can be seen from FIG. 4, within the first 83% of the axial chord length, the circumferential momentum at the near-surge point is reduced, and the loss of the cantilever stator blade within 2% of the blade height at the near-surge point is lower than the design point, which proves that the key aerodynamic parameter affecting the total pressure loss of the cantilever stator blade is the circumferential leakage momentum. As can be seen from the comparison graph of the total pressure loss coefficient and the circumferential leakage momentum along the chord direction in different blade height ranges, the total pressure loss coefficient increases along with the increase of the circumferential momentum, and hysteresis exists. In the 2% blade height range, the total pressure loss at the cantilever vane design point is 15.4%, while the total pressure loss at the near chunking point is 14.5%. When the cantilever stator blade is changed from a design point to a working condition close to a surge point, the total pressure loss is reduced by 0.9 percent. The circumferential flow of the leakage flow per unit axial chord length of the design point is higher than the near-surge point, and within 2 percent of the blade height, the total pressure loss at the near-surge point is lower than the design point.
The analysis shows that the key aerodynamic parameter determining the leakage loss of the root part of the cantilever stator blade is the circumferential leakage momentum of the unit axial chord length, the leakage loss within 2% of the blade height at the near-surge point can be effectively controlled by adopting the front loading design, the loss level is maintained near the design point, and the total pressure loss at the near-surge point is reduced by 0.9% for the cantilever stator blade of the case. Therefore, the front loading design of 8-12% chord length of the cantilever stator blade is an effective passive flow control means, and the flow loss within 2% of the blade height close to the surge point can be reduced.
Compared with the prior art that only a design point is concerned for controlling the cantilever stationary blade loss, the total pressure loss of the design point can be controlled at a lower level, the total pressure loss of a near surge working condition point is greatly increased, and the understanding of the influence of a root loading mode on the total pressure loss of the root of the cantilever stationary blade is lacked. The invention adopts the design of loading before the root, ensures that the leakage loss at the design point maintains a low level, effectively controls the total pressure loss level at the near surge point, and ensures that the root loss is slightly lower than the design point.
Through specific practical experiments, in the third-stage cantilever stationary blade embedded stage experiment verification of the multistage axial-flow compressor, the cantilever stationary blade adopting the front loading design can effectively control the total pressure loss within 2% of the blade height, and aiming at the cantilever stationary blade of the case, the total pressure loss at a near-surge point is reduced by 0.9% compared with a design point.
The foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (1)

1. A flow control method for reducing loss of a cantilever stator blade front loading design is characterized in that a first-stage compressor model consisting of an embedded third-stage rotor blade and a cantilever stator blade is established and is subjected to grid division, a numerical simulation method is adopted, a Reynolds average NS equation of a design point and a near surge point working condition is solved under an experimental working condition, and a front loading design structure for optimizing the uneven distribution of stator blade load along the chord length is obtained through comparison and analysis results;
the primary compressor model comprises a cantilever stator blade model which is assembled in the axial compressor model and is in front loading design and a rotor blade model which is arranged in front of the axial compressor model;
the root of the cantilever stator blade adopts a front loading design;
the grid division refers to: the main flow area of the blade channel is divided into O4H grids, the radial clearance between the main flow area and the wheel disc is H-shaped grids, and the height of the first layer of grids is set to be 3 x 10 -6 m；
The solving under the experimental condition is as follows: solving a Reynolds average Navier-Stokes equation by adopting a numerical simulation method:
Figure FDA0003928614730000011
wherein:
Figure FDA0003928614730000012
is a conservative type parameter vector of the vector,
Figure FDA0003928614730000013
Figure FDA0003928614730000014
and
Figure FDA0003928614730000015
respectively, a non-adhesive flux and a viscous flux,
Figure FDA0003928614730000016
qi is a heat source item and is a heat source item,
Figure FDA0003928614730000017
τ ij is the stress that is applied,
Figure FDA0003928614730000018
δ ij in the case of the kronecker symbol,
Figure FDA0003928614730000019
q is the source term of the signal,
Figure FDA00039286147300000110
Figure FDA00039286147300000111
represents an external force, W f Representing the work done by these external forces,
Figure FDA00039286147300000112
the comparative analysis result refers to that: carrying out different aspects of comparative analysis on a flow field of a blade root, comprising the following steps: comparing the distribution of the surface pressure coefficient difference, the total pressure loss coefficient and the circumferential leakage momentum along the chord direction of the blade root profile surface of the stator blade to obtain the circumferential leakage momentum taking the key aerodynamic parameter of the leakage loss of the cantilever stator blade root as the unit axial chord length, and adopting a front loading design to effectively control the leakage loss result within 2 percent of the blade height at the near surge point;
the optimized stator blade chord length design structure is as follows: the front loading design is adopted for 8% -12% of chord length.
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Citations (1)

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Publication number Priority date Publication date Assignee Title
CN109165440A (en) * 2018-08-22 2019-01-08 西北工业大学 A kind of axial flow compressor pneumatic matching optimization method between three-dimensional grade entirely

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US7686567B2 (en) * 2005-12-16 2010-03-30 United Technologies Corporation Airfoil embodying mixed loading conventions
JP5603800B2 (en) * 2011-02-22 2014-10-08 株式会社日立製作所 Turbine stationary blade and steam turbine equipment using the same
CN108710746A (en) * 2018-02-08 2018-10-26 哈尔滨广瀚燃气轮机有限公司 Take into account the anti-twisted design method that naval vessel combustion engine compressor blade and blade predeformation influences
CN110032784B (en) * 2019-04-01 2023-01-20 上海交通大学 Low-speed modeling design method of high-speed axial flow compressor with sealing labyrinth
CN110083968B (en) * 2019-05-08 2022-09-27 中国船舶重工集团公司第七0三研究所 Compressor characteristic prediction method based on correction of gas seal leakage influence numerical model

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CN109165440A (en) * 2018-08-22 2019-01-08 西北工业大学 A kind of axial flow compressor pneumatic matching optimization method between three-dimensional grade entirely

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