CN112304556A - Combined pumping system for improving periodicity of plane blade cascade and quality of outlet flow field - Google Patents

Combined pumping system for improving periodicity of plane blade cascade and quality of outlet flow field Download PDF

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Publication number
CN112304556A
CN112304556A CN202011279305.2A CN202011279305A CN112304556A CN 112304556 A CN112304556 A CN 112304556A CN 202011279305 A CN202011279305 A CN 202011279305A CN 112304556 A CN112304556 A CN 112304556A
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suction
grid plate
boundary layer
suction cavity
cavity
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CN112304556B (en
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韩吉昂
徐文峰
李聪
胡义
江达林
杨嗣涵
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Dalian Maritime University
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Dalian Maritime University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
    • G01M9/02—Wind tunnels
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Abstract

The present invention provides a combined pumping system for improving the periodicity of a planar cascade and the quality of an outlet flow field, comprising: the device comprises an upper end wall suction cavity, a left rotary table slideway, a cascade wind tunnel experiment table, a fixed seat of the cascade wind tunnel experiment table, a right rotary table and a right rotary table slideway. The invention utilizes the symmetrical suction of the left grid plate and the right grid plate and the symmetrical suction of the front boundary layer structure of the left grid plate and the right grid plate, controls the suction device arranged on the cascade through the throttle valve, realizes the control of the periodicity and the density flow ratio of the flow field in the cascade, and simultaneously can adjust the number and the relative positions of the suction holes on the left grid plate and the right grid plate according to the requirements of different cascades, thereby realizing the control effect of the periodicity and the density flow ratio of the flow field at the outlet of the cascade with higher efficiency and energy saving.

Description

Combined pumping system for improving periodicity of plane blade cascade and quality of outlet flow field
Technical Field
The invention relates to the technical field of impeller machinery, in particular to a combined pumping system for improving the periodicity of a plane blade grid and the quality of an outlet flow field.
Background
The plane blade cascade test is a basic test verified by a new blade type design method, and the test result can be directly used as the basis for evaluating and improving the aerodynamic performance of the blade type. In the basic research of the performance of the air compressor, the wind tunnel test research of the plane cascade occupies an extremely important position. In the process of plane cascade test of an aeroengine, the inherent periodic characteristic between cascade flow channels is ensured, and the method is one of important technical requirements for ensuring the validity and reliability of the cascade test data.
Through a plane cascade wind tunnel experiment, the aerodynamic performance of the blade profile under different incoming flows can be obtained, and technical data are accumulated for the design of a new blade profile. However, the flow field of the wind tunnel test section is influenced by the boundary layers of the end wall and the side wall of the blade grid, so that the deflection and the unevenness of the airflow in front of the grid are caused; the spanwise dimension of the test blade is limited, if the boundary layer is not processed, the area of a main flow area in a cascade flow field is shrunk, and the flow deviates from the real flow condition of a two-dimensional cascade. The flow field quality of the plane blade grid test piece specifically comprises axial density flow ratio, incoming flow unevenness before the grid, incoming flow skewness before the grid and flow field periodicity after the grid. Good flow field quality is an important technical requirement for ensuring validity and reliability of the cascade test data.
In the prior art, a suction pump is used for connecting a suction cavity of a plane cascade end wall and an inlet to flow a boundary layer suction cavity for suction. But has the following defects: (1) when the existing structure is used for sucking left and right grid plates, the left and right sucking capacities are easy to be asymmetric due to the fact that the existing structure is directly connected to a sucking pump, the sucking flow cannot be predicted, and the internal flow field structure of a blade grid is influenced; because the position of the suction holes/slits of the existing grid plate is fixed, the suction capacity can not be adjusted according to specific conditions under the conditions of different attack angles; (2) the existing suction structure does not arrange suction on the upper end wall, the periodicity of a flow field at the outlet of a plane cascade is seriously influenced due to the development influence of boundary layers of the upper end wall and the lower end wall, and the accuracy of an experimental result is seriously influenced by different influences on the periodicity of the flow field under different attack angles; (3) the existing boundary layer suction mode is that the boundary layer suction can be realized only by needing larger suction back pressure at a position far away from the front edge of a blade cascade inlet, and meanwhile, the symmetrical suction cannot be ensured because the suction capacities of the left and right boundary layers are asymmetrical.
Disclosure of Invention
When the left and right grid plates are sucked according to the conventional structure, the left and right sucking capacities are easy to be asymmetric due to the fact that the left and right grid plates are directly connected to a sucking pump, the sucking flow cannot be predicted, and the internal flow field structure of the blade grid is influenced; because the position of the suction holes/slits of the existing grid plate is fixed, the suction capacity can not be adjusted according to specific conditions under the conditions of different attack angles; the existing suction structure does not arrange suction on the upper end wall, the periodicity of a flow field at the outlet of a plane cascade is seriously influenced due to the development influence of boundary layers of the upper end wall and the lower end wall, and the accuracy of an experimental result is seriously influenced by different influences on the periodicity of the flow field under different attack angles; the existing boundary layer suction form is a technical problem that the boundary layer suction can be realized only by needing larger suction back pressure at a position far away from the front edge of an inlet of a blade cascade, and meanwhile, the symmetrical suction cannot be ensured due to the asymmetrical suction capability of the left and right boundary layers, so that a combined suction system for improving the periodicity of a plane blade cascade and the quality of an outlet flow field is provided. The invention mainly utilizes the symmetrical suction of the left grid plate and the right grid plate and the symmetrical suction of the front boundary layer structure of the left grid plate and the right grid plate, controls the suction device arranged on the cascade through the throttle valve, realizes the control of the periodicity and the density flow ratio of the flow field in the cascade, and simultaneously can adjust the number and the relative positions of the suction holes on the left grid plate and the right grid plate according to the requirements of different cascades, thereby realizing the control effect of the periodicity and the density flow ratio of the flow field at the outlet of the cascade with higher efficiency and energy saving.
The technical means adopted by the invention are as follows:
a combined pumping system for improving planar cascade periodicity and outlet flow field quality, comprising: the device comprises an upper end wall suction cavity, a left rotary table slideway, a cascade wind tunnel experiment table, a fixed seat of the cascade wind tunnel experiment table, a right rotary table and a right rotary table slideway;
the left turntable and the right turntable are identical in structure and symmetrically arranged and are respectively in rotating connection with the left turntable slide way and the right turntable slide way; the left turntable slideway and the right turntable slideway have the same structure and are symmetrically arranged on the cascade wind tunnel experiment table; the upper end wall suction cavity is arranged on the cascade wind tunnel experiment table, and the upper end of the upper end wall suction cavity is provided with an upper end wall suction hole; the cascade wind tunnel experiment table is arranged on the fixed seat of the cascade wind tunnel experiment table, and a hollow cavity structure is arranged inside the cascade wind tunnel experiment table;
the left turntable is provided with a left grid plate fixing block, a left grid plate and a left inflow boundary layer suction seam, the left grid plate is fixedly connected with the left grid plate fixing block, and the left inflow boundary layer suction seam is formed below the left grid plate fixing block and is at least provided with one suction seam;
the right turntable is provided with a right grid plate fixing block, a right grid plate and a right inflow boundary layer suction seam, and the right grid plate fixing block and the left grid plate fixing block are same in structure and are symmetrically arranged; the right grid plate is fixedly connected with the right grid plate fixing block, has the same structure as the left grid plate and is symmetrically arranged; the right inflow boundary layer suction slits are formed below the right grid plate fixing block, have the same structure and the same number as the left inflow boundary layer suction slits and are symmetrically arranged;
a hollow cavity communicated with the hollow cavity structure is formed between the left turntable and the right turntable, a testing blade device is installed in the hollow cavity, and two sides of the testing blade device are fixed through testing blade fixing holes which are symmetrically arranged on the left grid plate and the right grid plate and have the same structure; the front side and the rear side of the testing blade device are respectively in contact connection with an upper guide plate and a lower guide plate, and the upper guide plate and the lower guide plate are both arranged in a space region where the hollow cavity chamber is communicated with the hollow cavity structure;
the outer wall surface of the left rotary table is provided with a left incoming flow boundary layer suction cavity communicated with a boundary layer suction cavity pressure stabilizing box, a hollow cavity I is arranged inside the left rotary table and communicated with the left incoming flow boundary layer suction seam, and the left incoming flow boundary layer suction seam is communicated with the hollow cavity;
the outer wall surface of the right rotary disc is provided with a right incoming flow boundary layer suction cavity communicated with a boundary layer suction cavity pressure stabilizing box, the right incoming flow boundary layer suction cavity and the left incoming flow boundary layer suction cavity have the same structure and are symmetrically arranged, a hollow cavity II is arranged inside the right incoming flow boundary layer suction cavity and is communicated with the right incoming flow boundary layer suction seam, and the right incoming flow boundary layer suction seam is communicated with the hollow cavity;
the test blade device consists of a row of a plurality of test blades, a group of test blade suction surface suction hole structures with the same structure are symmetrically arranged on two sides of the back surface of each test blade, and the test blade suction surface suction hole structures on two sides are respectively arranged on the left side grid plate and the right side grid plate and are symmetrically distributed; the test blade at the uppermost position is connected with the upper end wall suction cavity;
the outer wall surface of the left grid plate fixing block is provided with a left grid plate suction cavity communicated with the end wall suction cavity pressure stabilizing box, the inside of the left grid plate fixing block is provided with a hollow cavity III, and the left grid plate suction cavity is communicated with the hollow cavity through the suction hole structure of the suction surface of the test blade;
the outer wall surface of the right grid plate fixing block is provided with a right grid plate suction cavity communicated with the end wall suction cavity pressure stabilizing box, the right grid plate suction cavity and the left grid plate suction cavity are same in structure and are symmetrically arranged, a hollow cavity IV is arranged inside the right grid plate suction cavity, and the right grid plate suction cavity is communicated with the hollow cavity through the suction hole structure of the suction surface of the test blade.
Furthermore, the test blade at the uppermost position in the test blade device is a test blade with a suction hole, and the front edge of the test blade is in contact connection with the upper guide plate;
the test blade with the suction hole is communicated with the suction holes of the upper end wall suction cavity in a one-to-one correspondence manner through a pipeline, the number of the suction holes of the upper end wall suction cavity can be adjusted according to the requirement in the experimental process, the suction position of the suction holes of the upper end wall suction cavity is adjusted under the condition of different cascade attack angles, the accumulation of low-energy fluid clusters near the upper end wall of the cascade is reduced, the flow field quality of the outlet flow field of the planar cascade is efficiently, energy-saving and accurately adjusted, and the periodicity of the cascade is improved;
the testing blade at the lowest position in the testing blade device is in contact connection with the lower guide plate, so that the effect of closing the lower end wall of the blade cascade is achieved, the airflow leakage of the lower end wall of the blade cascade is reduced, and the airflow close to the lower end wall flows out of the blade cascade along the pressure surface side of the testing blade at the lowest position in the testing blade device;
the test blade may be a compressor blade or a turbine blade.
Furthermore, at least one left grid plate front edge suction slit is formed in the left grid plate and is positioned below the suction hole structure of the suction surface of the test blade and at the front edge of the test blade device, so that the thickness of a blade grid boundary layer is further reduced, and the influence caused by the boundary layer is reduced; the seam opening direction of the front edge suction seam of the left grid plate is parallel to the central axis of the seam opening direction of the suction seam of the left inflow boundary layer, and in order to ensure the suction capability of the end wall, the widths of the front edge suction seam of the left grid plate and the suction seam of the left inflow boundary layer are both smaller than or equal to the diameter of the suction hole of the suction surface of the test blade;
and the right grid plate is symmetrically provided with right grid plate front edge suction slits which have the same structure and the same number as the left grid plate front edge suction slits.
Furthermore, the bottom of the upper end wall suction cavity is fixed to one side of the top of the cascade wind tunnel experiment table through an upper end wall suction cavity fixing bolt hole, a hollow cavity V communicated with the upper end wall suction cavity suction hole is formed inside the upper end wall suction cavity, an upper end wall suction cavity left flange and an upper end wall suction cavity right flange are arranged on two sides of the upper end wall suction cavity fixing bolt hole respectively, the upper end wall suction cavity left flange and the upper end wall suction cavity right flange are communicated with a vacuum pump I with a frequency converter through a pipeline, and the suction flow in the suction cavity is adjusted by changing the suction capacity of the vacuum pump I.
Furthermore, each group of the suction hole structure of the suction surface of the test blade consists of a plurality of suction holes of the suction surface of the test blade, and the central line of the suction hole structure of the suction surface of the test blade is obtained by offsetting the side contour line of the suction surface of the blade, so that the suction surface can be better attached, and the suction effect is better.
Furthermore, the suction holes of the suction surface of the test blade are threaded holes, the suction holes of the suction surface of the test blade are blocked by flat head screws under the condition of suction, and meanwhile, the inner surfaces of the left grid plate and the right grid plate are ensured to be smooth and flat without generating bulges and pits; and adjusting the number of the suction holes of the suction surface of the test blade according to the numerical settlement results under different attack angles, so that the suction effect is more obvious, and the density flow ratio of the flow field at the outlet of the blade cascade is reduced.
Furthermore, the left grid plate suction cavity is fixed on the left grid plate fixing block through a left grid plate suction cavity fixing bolt hole, and an upper side flange of the left grid plate suction cavity and a lower side flange of the left grid plate suction cavity are symmetrically arranged on two sides of the left grid plate suction cavity and are connected with a left throttling valve of an end wall suction cavity pressure stabilizing box arranged on the end wall suction cavity pressure stabilizing box through a pipeline;
the right side grid plate suction cavity is fixed on the right side grid plate fixing block through a right side grid plate suction cavity fixing bolt hole, and a right side grid plate suction cavity upper side flange and a right side grid plate suction cavity lower side flange are symmetrically arranged on two sides of the right side grid plate suction cavity and are connected with an end wall suction cavity pressure stabilizing box right side throttle valve arranged on the end wall suction cavity pressure stabilizing box through a pipeline.
Furthermore, an end wall suction cavity pressure stabilizing box flange is arranged at the top of the end wall suction cavity pressure stabilizing box, an end wall suction cavity pressure stabilizing box left side throttle valve and an end wall suction cavity pressure stabilizing box left side pressure measuring probe are sequentially arranged on the left side pipeline from left to right, and an end wall suction cavity pressure stabilizing box right side throttle valve and an end wall suction cavity pressure stabilizing box right side pressure measuring probe which are identical in structure are symmetrically arranged on the right side pipeline;
the left pressure probe of the end wall suction cavity pressure stabilizing box and the right pressure probe of the end wall suction cavity pressure stabilizing box are identical in structure and symmetrically arranged, the left pressure probe and the right pressure probe are connected to a test system through pneumatic pipelines, collected pressure signals are converted into electric signals through a signal converter, the electric signals are fed back to a computer, the suction flow at the position can be calculated, and the left and right suction flows are controlled to be symmetrical through the left throttle valve of the wall suction cavity pressure stabilizing box and the right throttle valve of the end wall suction cavity pressure stabilizing box.
Furthermore, the left incoming flow boundary layer suction cavity is fixed on the left turntable through a left incoming flow boundary layer suction cavity fixing bolt hole, and a left incoming flow boundary layer suction cavity upper side flange and a left incoming flow boundary layer suction cavity lower side flange are symmetrically arranged on two sides of the left incoming flow boundary layer suction cavity and are connected with a boundary layer suction cavity pressure stabilizing box left side throttle valve arranged on the boundary layer suction cavity pressure stabilizing box through a pipeline;
the right incoming flow boundary layer suction cavity is fixed on the right turntable through a right incoming flow boundary layer suction cavity fixing bolt hole, a right incoming flow boundary layer suction cavity upper side flange and a right incoming flow boundary layer suction cavity lower side flange are symmetrically arranged on two sides of the right incoming flow boundary layer suction cavity and are connected with a boundary layer suction cavity pressure stabilizing box right side throttle valve arranged on a boundary layer suction cavity pressure stabilizing box through a pipeline.
Furthermore, the top of the boundary layer suction cavity pressure stabilizing box is provided with a boundary layer suction cavity pressure stabilizing box flange, a boundary layer suction cavity pressure stabilizing box left throttle valve and a boundary layer suction cavity pressure stabilizing box left pressure measuring probe are sequentially arranged on the left pipeline from left to right, and a boundary layer suction cavity pressure stabilizing box right throttle valve and a boundary layer suction cavity pressure stabilizing box right pressure measuring probe which are identical in structure are symmetrically arranged on the right pipeline;
the left pressure probe of the surface layer suction cavity pressure stabilizing box and the right pressure probe of the surface layer suction cavity pressure stabilizing box are in the same structure and are symmetrically arranged, the left pressure probe and the right pressure probe of the surface layer suction cavity pressure stabilizing box are connected to a test system through pneumatic pipelines, collected pressure signals are converted into electric signals through a signal converter, the electric signals are fed back to a computer, the suction flow at the position can be calculated, the left side throttling valve of the surface layer suction cavity pressure stabilizing box and the right side throttling valve of the surface layer suction cavity pressure stabilizing box control the symmetry of the left side suction flow and the right side suction flow, and the left side pressure probe and the right side pressure probe of the surface layer suction cavity pressure stabilizing box guarantee the symmetry of the left side suction flow and the right side suction flow.
The working principle of the invention is as follows:
the upper end wall suction cavity left flange and the upper end wall suction cavity right flange on the upper end wall suction cavity are communicated with the vacuum pump I through pipeline connection, the flow in the upper end wall suction cavity can be controlled by controlling the vacuum flow of the vacuum pump I, and then the suction capacity of the suction hole on the suction hole test blade is controlled.
The left side grid plate suction cavity upper side flange and the left side grid plate suction cavity lower side flange arranged on the left side grid plate suction cavity are connected with an end wall suction cavity pressure stabilizing box left side throttle valve on the end wall suction cavity pressure stabilizing box through pipelines, the suction flow can be adjusted through adjusting the opening degree of the throttle valve, the right side structure is completely symmetrical with the left side, and whether the left side grid plate suction flow is the same or not is judged after the pressure value is measured through a surface layer suction cavity pressure stabilizing box left side pressure measuring probe is calculated through a test system, and the symmetrical suction of the grid end walls is ensured. An end wall suction cavity pressure stabilizing box flange on the end wall suction cavity pressure stabilizing box is connected with the vacuum pump II through a pipeline, the control of end wall suction flow can be realized by controlling the vacuum flow of the vacuum pump II, and the suction flow can be finely adjusted by adjusting a throttle valve on the end wall suction cavity pressure stabilizing box according to the requirements of experimental conditions.
The left side inflow boundary layer suction cavity upper side flange and the left side inflow boundary layer suction cavity lower side flange which are arranged on the left side inflow boundary layer suction cavity are connected with a boundary layer suction cavity pressure stabilizing box left side throttle valve which is arranged on a boundary layer suction cavity pressure stabilizing box through pipelines, the suction flow can be adjusted by adjusting the opening of the throttle valve, the right side structure is completely symmetrical with the left side, and whether the suction flow of the grid plates on the left side and the right side is the same or not is judged after the pressure value measured by a pressure measuring probe on the left side of the boundary layer suction cavity pressure stabilizing box is calculated by a test system, so that the symmetrical suction of the grid boundary layer is ensured. The boundary layer suction cavity pressure stabilizing box flange on the boundary layer suction cavity pressure stabilizing box is connected with the vacuum pump III through a pipeline, the control of the boundary layer suction flow can be realized by controlling the vacuum flow of the vacuum pump III, and the suction flow can be finely adjusted by adjusting a throttle valve on the left side of the boundary layer suction cavity pressure stabilizing box according to the requirements of experimental conditions.
Compared with the prior art, the invention has the following advantages:
1. the combined suction system for improving the periodicity and the outlet flow field quality of the plane cascade provided by the invention utilizes the symmetrical suction of the left grid plate and the right grid plate and the symmetrical suction of the front boundary layer structures of the left grid plate and the right grid plate, controls the suction device arranged on the cascade through the throttle valve, realizes the control of the periodicity and the density flow ratio of the flow field in the cascade, can adjust the number and the relative positions of the suction holes on the left grid plate and the right grid plate according to the requirements of different cascades, and realizes the control effect of the periodicity and the density flow ratio of the outlet flow field of the cascade more efficiently and more energy-saving.
2. According to the combined suction system for improving the periodicity of the plane blade cascade and the quality of the outlet flow field, the test blade with the suction hole is correspondingly communicated with the suction holes of the upper end wall suction cavity arranged on the upper end wall suction cavity one by one through the pipeline, the number of the suction holes can be adjusted and the suction position of the suction hole can be adjusted under the condition of different blade cascade attack angles according to the requirement in the experimental process, the accumulation of low-energy fluid clusters near the upper end wall of the blade cascade is reduced, the quality of the outlet flow field of the plane blade cascade is efficiently, energy-saving and accurately adjusted, and the periodicity of the blade cascade is improved.
3. According to the combined suction system for improving the periodicity of the plane blade grid and the quality of the outlet flow field, the central line of the suction hole of the suction surface of the test blade arranged on the left grid plate is obtained by offsetting the side contour line of the suction surface of the blade, the suction surface can be better attached, the suction effect is better, the structure identical to that of the left grid plate is arranged on the right grid plate, the suction hole of the suction surface of the test blade is a threaded hole, the suction hole can be blocked by a flat head screw under the suction condition, meanwhile, the number of the suction holes of the suction surface of the test blade can be adjusted according to numerical settlement results under different attack angles, the suction effect is more obvious, and the density flow ratio of the outlet flow field of the blade grid is reduced.
4. The invention provides a combined suction system for improving the periodicity of a plane blade grid and the quality of an outlet flow field, wherein a left grid plate suction cavity is fixed on a left rotary table through a left grid plate suction cavity fixing bolt hole, a left grid plate suction cavity upper side flange and a left grid plate suction cavity lower side flange are arranged on the left grid plate suction cavity and are connected with an end wall suction cavity pressure stabilizing box left side throttle valve and an end wall suction cavity pressure stabilizing box right side throttle valve on an end wall suction cavity pressure stabilizing box through pipelines, an end wall suction cavity pressure stabilizing box flange end wall suction cavity left side throttle valve end wall suction cavity left side pressure probe end wall suction cavity pressure stabilizing box right side throttle valve is arranged on the end wall suction cavity pressure stabilizing box, wherein the end wall suction cavity pressure probe left side pressure probe and the end wall suction cavity pressure stabilizing box right side pressure probe are connected to, the collected pressure signals are converted into electric signals through the signal converter and then fed back to the computer, so that the suction flow can be calculated, and the left and right sides of the suction flow can be controlled to be symmetrical through the throttle valve.
5. The invention provides a combined suction system for improving the periodicity of a plane blade cascade and the quality of an outlet flow field, wherein a left-side incoming flow boundary layer suction cavity is fixed on a left-side rotary table through a left-side incoming flow boundary layer suction cavity fixing bolt hole, a left-side incoming flow boundary layer suction cavity upper side flange and a left-side incoming flow boundary layer suction cavity lower side flange are arranged on the left-side incoming flow boundary layer suction cavity, the left-side incoming flow boundary layer suction cavity upper side flange and the left-side incoming flow boundary layer suction cavity lower side flange are connected with a boundary layer suction cavity pressure stabilizing box left-side throttling valve and a boundary layer suction cavity pressure stabilizing box right-side throttling valve on a boundary layer suction cavity pressure stabilizing box through pipelines, an boundary layer suction cavity flange boundary layer pressure stabilizing box left-side pressure measuring probe pressure stabilizing cavity pressure stabilizing box left-side throttling valve and a boundary layer suction cavity left-side throttling valve on the boundary layer suction cavity pressure stabilizing box right-side throttling valve are arranged on the boundary layer suction cavity pressure stabilizing box, a boundary layer According to the test system, the collected pressure signals are converted into electric signals through the signal converter and then fed back to the computer, the suction flow can be calculated, the symmetry of the left and right suction flows can be controlled through the throttle valve, and the symmetry of the left and right suction flows can be guaranteed through the left and right pressure measuring probes.
In conclusion, the technical scheme of the invention can solve the problems that when the left grid plate and the right grid plate are sucked by the existing structure, the left suction capacity and the right suction capacity are asymmetric due to the direct connection on the suction pump, the suction flow cannot be predicted, and the internal flow field structure of the blade grid is influenced; because the position of the suction holes/slits of the existing grid plate is fixed, the suction capacity can not be adjusted according to specific conditions under the conditions of different attack angles; the existing suction structure does not arrange suction on the upper end wall, the periodicity of a flow field at the outlet of a plane cascade is seriously influenced due to the development influence of boundary layers of the upper end wall and the lower end wall, and the accuracy of an experimental result is seriously influenced by different influences on the periodicity of the flow field under different attack angles; the existing boundary layer suction mode is that the boundary layer suction can be realized only by needing larger suction back pressure at a position far away from the front edge of a blade cascade inlet, and meanwhile, the problem that the symmetrical suction cannot be ensured because the suction capacities of the left and right boundary layers are asymmetrical.
Based on the reasons, the invention can be widely popularized in the fields of plane cascade wind tunnel blowing tests and the like.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a plane cascade wind tunnel experiment table of the invention.
FIG. 2 is a schematic structural diagram of a left turntable of a plane cascade wind tunnel experiment table.
FIG. 3 is a partially enlarged view of a plane cascade wind tunnel experiment table of the present invention.
FIG. 4 is a front view of the plane cascade wind tunnel experiment table without a left turntable.
FIG. 5 is an oblique view of the plane cascade wind tunnel experiment table without a left turntable.
Figure 6 is a schematic view of the upper end wall suction chamber of the present invention.
Fig. 7 is a front view of the left turntable of the present invention.
Figure 8 is a schematic diagram of the end wall suction chamber plenum of the present invention.
FIG. 9 is a schematic diagram of a plenum box with a surface layer suction chamber according to the present invention.
FIG. 10 is a system flow diagram of the present invention.
FIG. 11 is a schematic view showing the structure of the suction slit at the leading edge of the left louver in example 2 of the present invention.
In the figure: 1. an upper endwall suction chamber; 2. a left turntable; 3. a left grid plate suction cavity; 4. a left incoming flow boundary layer suction chamber; 5. a left turntable slide; 6. a cascade wind tunnel experiment table; 7. a fixed seat of the cascade wind tunnel experiment table; 8. a right turntable; 9. a right grid plate suction cavity; 10. a left grid plate fixing block; 11. a left grid plate; 12. the left inflow boundary layer suction slot; 13. a suction slit is arranged at the front edge of the left grid plate; 14. testing the blade fixing holes; 15. testing a suction hole of a suction surface of the blade; 16. a right grid plate; 17. testing the blade with a suction hole; 18. an upper deflector; 19. a lower deflector; 20. testing the blade; 21. an upper end wall suction lumen suction aperture; 22. an upper endwall suction chamber left flange; 23. an upper endwall suction chamber right flange; 24. the upper end wall suction cavity is fixed with a bolt hole; 25. an upper flange of the left grid plate suction cavity; 26. an upper flange of the suction cavity of the left incoming flow boundary layer; 27. a left incoming flow boundary layer suction cavity fixing bolt hole; 28. a bolt hole is fixed in the suction cavity of the left grid plate; 29. a flange at the lower side of the left grid plate suction cavity; 30. a flange at the lower side of the suction cavity of the left incoming flow boundary layer; 31. an end wall suction chamber surge tank; 32. an end wall suction cavity surge tank flange; 33. a left throttle valve of a pressure stabilizing box of the end wall suction cavity; 34. a pressure measuring probe is arranged on the left side of the pressure stabilizing box of the end wall suction cavity; 35. a pressure measuring probe is arranged on the right side of the pressure stabilizing box of the end wall suction cavity; 36. a right throttle valve of a pressure stabilizing box of the end wall suction cavity; 37. a surface layer suction cavity pressure stabilizing box; 38. a surface layer suction cavity surge tank flange; 39. a pressure measuring probe is arranged on the left side of the pressure stabilizing box of the surface layer suction cavity; 40. a left throttle valve of a surface layer suction cavity pressure stabilizing box; 41. a pressure measuring probe is arranged on the right side of the pressure stabilizing box of the surface layer suction cavity; 42. and a throttle valve on the right side of the pressure stabilizing box of the boundary layer suction cavity.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
As shown in the figure, the invention provides a combined suction system for improving the periodicity of the planar cascade and the quality of the outlet flow field, namely a planar cascade system with combined suction, which can realize the control of the thickness of the inflow boundary layer of the cascade inlet and the separation range of the cascade corner region by adjusting the suction flow and the suction gap structure at different positions in the system, thereby realizing the adjustment of the periodicity of the flow field and the quality of the outlet flow field in the cascade.
The combined pumping system for improving planar cascade periodicity and outlet flow field quality comprises: the device comprises an upper end wall suction cavity 1, a left rotary table 2, a left rotary table slideway 5, a cascade wind tunnel experiment table 6, a cascade wind tunnel experiment table fixing seat 7, a right rotary table 8 and a right rotary table slideway;
the left turntable 2 and the right turntable 8 are identical in structure and symmetrically arranged and are respectively in rotating connection with the left turntable slideway 5 and the right turntable slideway; the left turntable slideway 5 and the right turntable slideway have the same structure and are symmetrically arranged on the cascade wind tunnel experiment table 6; the upper end wall suction cavity 1 is arranged on the cascade wind tunnel experiment table 6, the upper end of the upper end wall suction cavity is provided with upper end wall suction cavity suction holes 21, the upper end wall suction cavity suction holes 21 are not communicated with outside air, and are communicated with the suction holes on the testing blades 17 with the suction holes one by one through pneumatic pipes, the number and the positions of the suction holes on the testing blades 17 with the suction holes can be adjusted according to experiment conditions, and the gathering of low-energy fluid near the upper end wall can be efficiently and accurately controlled; the cascade wind tunnel experiment table 6 is arranged on the fixed seat 7 of the cascade wind tunnel experiment table, and a hollow cavity structure is arranged inside the cascade wind tunnel experiment table 6;
the left turntable 2 is provided with a left grid plate fixing block 10, a left grid plate 11 and a left inflow boundary layer suction slit 12, the left grid plate 11 is fixedly connected with the left grid plate fixing block 10, and the left inflow boundary layer suction slit 12 is arranged below the left grid plate fixing block 10 and is provided with at least one suction slit;
the right turntable 8 is provided with a right grid plate fixing block, a right grid plate 16 and a right inflow boundary layer suction seam, and the right grid plate fixing block and the left grid plate fixing block 10 are same in structure and are symmetrically arranged; the right side grid plate 16 is fixedly connected with the right side grid plate fixing block, the right side inflow boundary layer suction slits are formed below the right side grid plate fixing block, and are the same as the left side inflow boundary layer suction slits 12 in structure, equal in number and symmetrically arranged;
a hollow cavity communicated with the hollow cavity structure is formed between the left turntable 2 and the right turntable 8, a testing blade device is installed in the hollow cavity, and two sides of the testing blade device are fixed through testing blade fixing holes 14 formed in the left grid plate 11 and the right grid plate 16; the front side and the rear side of the testing blade device are respectively in contact connection with an upper guide plate 18 and a lower guide plate 19, and the upper guide plate 18 and the lower guide plate 19 are both arranged in a space region where the hollow cavity chamber is communicated with the hollow cavity structure;
the outer wall surface of the left rotary table 2 is provided with a left inflow boundary layer suction cavity 4 communicated with a boundary layer suction cavity pressure stabilizing box 37, a hollow cavity I is arranged inside the left rotary table and communicated with the left inflow boundary layer suction slit 12, and the left inflow boundary layer suction slit 12 is communicated with the hollow cavity;
a right incoming flow boundary layer suction cavity communicated with the boundary layer suction cavity pressure stabilizing box 37 is arranged on the outer wall surface of the right rotary disc 8, the right incoming flow boundary layer suction cavity and the left incoming flow boundary layer suction cavity 4 are same in structure and symmetrically arranged, a hollow cavity II is arranged inside and communicated with the right incoming flow boundary layer suction seam, and the right incoming flow boundary layer suction seam is communicated with the hollow cavity;
the test blade device is composed of a row of a plurality of test blades 20, a group of test blade suction surface suction hole structures with the same structure are symmetrically arranged on two sides of the back surface of each test blade 20, and the test blade suction surface suction hole structures on two sides are respectively arranged on the left grid plate 11 and the right grid plate 16 and are symmetrically distributed; the uppermost test blade 20 is connected to the upper endwall suction chamber 1;
the outer wall surface of the left grid plate fixing block 10 is provided with a left grid plate suction cavity 3 communicated with the end wall suction cavity pressure stabilizing box 31, the inside of the left grid plate suction cavity is provided with a hollow cavity III, and the left grid plate suction cavity is communicated with the hollow cavity through the suction hole structure of the suction surface of the test blade;
the outer wall surface of the right grid plate fixing block is provided with a right grid plate suction cavity 9 communicated with an end wall suction cavity pressure stabilizing box 31, the right grid plate suction cavity 9 and the left grid plate suction cavity 3 are in the same structure and are symmetrically arranged, a hollow cavity IV is arranged inside the right grid plate suction cavity 9, and the right grid plate suction cavity is communicated with the hollow cavity through the suction hole structure of the suction surface of the test blade.
Example 1
As shown in fig. 1 to 10, a combined suction system for improving the periodicity of a planar cascade and the quality of an outlet flow field comprises an upper end wall suction cavity 1, a left rotary table 2, a left cascade plate suction cavity 3, a left inflow boundary layer suction cavity 4, a left rotary table slideway 5, a cascade wind tunnel experiment table 6, a cascade wind tunnel experiment table fixing seat 7, a right rotary table 8 and a right cascade plate suction cavity 9. The left turntable 2 and the right turntable 8 are of the same structure, are of semicircular plate structures, are symmetrically arranged and are respectively in rotating connection with the left turntable slide way 5 and the right turntable slide way, and the left turntable 2 and the right turntable 8 can be driven by a motor or manually to respectively rotate in the left turntable slide way 5 and the right turntable slide way; the left turntable slideway 5 and the right turntable slideway have the same structure, are annular structures and are symmetrically arranged on the cascade wind tunnel experiment table 6; the bottom of the upper end wall suction cavity 1 is installed on one side of the top of the cascade wind tunnel experiment table 6 through an upper end wall suction cavity fixing bolt hole 24 and a bolt, a hollow cavity V is arranged inside, an upper end wall suction cavity suction hole 21 communicated with the hollow cavity V is arranged at the upper end of the upper end wall suction cavity suction hole, an upper end wall suction cavity left flange 22 and an upper end wall suction cavity right flange 23 are respectively arranged on two sides of the upper end wall suction cavity suction hole, the upper end wall suction cavity left flange 22 and the upper end wall suction cavity right flange 23 are communicated with a vacuum pump I with a frequency converter through a pipeline, and the adjustment of the suction flow in the suction cavity; the cascade wind tunnel experiment table 6 is installed on the cascade wind tunnel experiment table fixing seat 7, and a hollow cavity structure is arranged inside the cascade wind tunnel experiment table 6.
Be provided with left side grid tray fixed block 10 on the carousel 2 of left side, left side grid tray 11 and left side incoming flow boundary layer suction seam 12, notch I has been seted up on the carousel 2 of left side, in 11 embedding notches I of left side grid tray and through bolt fixed connection with left side grid tray fixed block 10, left side grid tray fixed block 10 passes through bolt fixed connection with the outer wall of left side carousel, left side incoming flow boundary layer suction seam 12 is equipped with one, for rectangular form, set up in the below of left side grid tray fixed block 10. The symmetry is provided with the structure the same with left side carousel 2 on right side carousel 8, right side grid tray fixed block promptly, right side grid tray 16 and the suction seam of the side layer that comes to flow, be equipped with the right side grid tray fixed block on the right side carousel 8, right side grid tray 16, the suction seam of the side layer that comes to flow, notch II has been seted up on the right side carousel 8, bolt fixed connection is passed through in the 16 embedding notches II of right side grid tray and with the right side grid tray fixed block, the outer wall of right side grid tray fixed block and right side carousel 8 passes through bolt fixed connection, the side is come to flow and is connect the suction seam of layer and be equipped with one, for rectangular form, set.
The left grid plate 11 is provided with a test blade fixing hole 14 and a plurality of test blade suction surface suction holes 15, wherein the central lines of the test blade suction surface suction holes 15 are obtained by offsetting the side profile line of the blade suction surface and can better fit the suction surface, so that the suction effect is better, the left grid plate 11 is provided with a strip-shaped left grid plate front edge suction slit 13 which is positioned below the structure of the test blade suction surface suction holes and at the front edge of a test blade device, and the left grid plate front edge suction slit 13 can further reduce the thickness of a blade grid boundary layer and reduce the influence caused by the boundary layer; the seam opening direction of the front edge suction seam 13 of the left grid plate is parallel to the central axis of the seam opening direction of the suction seam 12 of the incoming flow boundary layer on the left side, and in order to ensure the suction capacity of the end wall, the width of each of the two suction seams is smaller than or equal to the diameter of the suction hole 15 of the suction surface of the test blade. The right side grid plate 16 is symmetrically provided with the same structure as the left side grid plate 11, namely a rectangular front edge suction slit of the right side grid plate, a test blade fixing hole 14 and a test blade suction surface suction hole 15.
A hollow cavity communicated with the hollow cavity structure is formed between the left turntable 2 and the right turntable 8, a testing blade device is arranged in the hollow cavity, and two sides of the testing blade device are fixed through testing blade fixing holes 14 formed in a left grid plate 11 and a right grid plate 16; the front side and the rear side of the testing blade device are respectively in contact connection with an upper guide plate 18 and a lower guide plate 19, and the upper guide plate 18 and the lower guide plate 19 are arranged in a space area where the hollow cavity and the hollow cavity structure are communicated. Specifically, the blade testing device is composed of a row of a plurality of testing blades 20, the cross section of each testing blade 20 is crescent, a group of blade suction surface suction hole structures are arranged on two sides of the back surface of each testing blade 20, and the blade suction surface suction hole structures on the two sides are respectively arranged on the left grid plate 11 and the right grid plate 16 and are symmetrically distributed; the uppermost test vane 20 is connected to the upper endwall suction chamber 1. The testing blade 20 at the uppermost position in the testing blade device is a testing blade 17 with a suction hole, the testing blade 20 is arranged at the uppermost position of the left grid plate 11, the front edge of the testing blade is in contact with an upper guide plate 18, the testing blade 20 at the lowermost position in the testing blade device is in contact connection with a lower guide plate 19, and the upper guide plate and the lower guide plate play a role in limiting air flow diffusion and guiding air flow. The test blade may be a compressor blade or a turbine blade.
The test blade 17 with the suction hole is communicated with the suction holes 21 of the upper end wall suction cavity in a one-to-one correspondence mode through a pipeline, the number of the suction holes 21 of the upper end wall suction cavity can be adjusted according to the requirement in the experimental process, the suction position of the suction holes 21 of the upper end wall suction cavity can be adjusted under the condition of different cascade attack angles, the gathering of low-energy fluid clusters near the upper end wall of the cascade can be reduced, the flow field quality of the outlet of the planar cascade can be adjusted efficiently, energy can be saved accurately, and the periodicity of the cascade can be improved.
Above-mentioned every group test blade suction surface suction hole structure comprises a plurality of test blade suction surface suction hole 15 of a column, be the arc and distribute, the central line of every group test blade suction surface suction hole structure is obtained by blade suction surface side contour line biasing, make test blade suction surface suction hole structure more inseparable with the subsides of blade suction surface side contour line, laminating suction surface that can be better (in impeller machinery field, the suction surface is also called the leaf back, refer to the pitch arc in the leaf type outside), make the effect of suction better. Specifically, the suction holes 15 of the suction surface of the test blade are threaded holes, the suction holes 15 of the suction surface of the test blade are blocked by flat head screws under the condition of suction, the flat head screws can not only block the suction holes 15 of the suction surface of the test blade, but also ensure that the inner surfaces of the left grid plate 11 and the right grid plate 16 of the test blade grid are smooth and flat, and no bulge or pit is generated; the number of the suction holes 15 of the suction surface of the test blade is adjusted according to the numerical settlement results under different attack angles (namely the suction holes 15 of the suction surface of the test blade which is not needed to be used are blocked by flat head screws, and the suction holes 15 of the suction surface of the test blade which is not blocked normally suck), so that the suction effect is more obvious, and the density flow ratio of the flow field of the outlet of the blade cascade is reduced. Specifically, when the dense flow at the outlet of the blade cascade is large and the periodicity of the outlet flow field is poor, the number of the suction holes 15 on the suction surface of the test blade needs to be adjusted. Wherein, the starting position of the suction hole 15 of the suction surface of the test blade is before the starting point of the angular separation, and when the length of the profile line of the suction surface occupied by the suction hole 15 of the suction surface of the test blade exceeds 50% of the total length, the suction effect is more obvious.
The outer wall surface of the left rotary table 2 is provided with a left inflow boundary layer suction cavity 4 communicated with a boundary layer suction cavity pressure stabilizing box 37, a hollow cavity I is arranged inside and communicated with a left inflow boundary layer suction slit 12, and the left inflow boundary layer suction slit 12 is communicated with the hollow cavity. The outer wall surface of the right rotary disk 8 is provided with a right incoming flow boundary layer suction cavity communicated with the boundary layer suction cavity pressure stabilizing box 37, a hollow cavity II is arranged in the right rotary disk and communicated with a right incoming flow boundary layer suction seam, and the right incoming flow boundary layer suction seam is communicated with the hollow cavity. The left inflow boundary layer suction cavity 4 and the right inflow boundary layer suction cavity are the same in structure and are symmetrically arranged.
The outer wall face of the left grid plate fixing block 10 is provided with a left grid plate suction cavity 3 communicated with the end wall suction cavity pressure stabilizing box 31, the inside of the left grid plate suction cavity is provided with a hollow cavity III, the left grid plate suction cavity is communicated with the hollow cavity through a test blade suction surface suction hole structure, and in the actual experiment operation process, in order to reduce complexity in the test piece installation process, the left grid plate suction cavity 3 is installed on the left grid plate fixing block 10. The outer wall surface of the right grid plate fixing block is provided with a right grid plate suction cavity 9 communicated with the end wall suction cavity pressure stabilizing box 31, and the inside of the right grid plate fixing block is provided with a hollow cavity IV communicated with the hollow cavity through a suction hole structure of a suction surface of the test blade. The left grid plate suction cavity 3 and the right grid plate suction cavity 9 are the same in structure and are symmetrically arranged.
Specifically, the left side grid plate suction cavity 3 is fixed on the left side rotary table 2 through a left side grid plate suction cavity fixing bolt hole 28 and a bolt, a left side grid plate suction cavity upper side flange 25 and a left side grid plate suction cavity lower side flange 29 are symmetrically arranged on two sides of the left side grid plate suction cavity 3, and are connected with an end wall suction cavity pressure stabilizing box left side throttle valve 33 on an end wall suction cavity pressure stabilizing box 31 through a pipeline. Similarly, the right grid plate suction cavity 9 is fixed on the right grid plate fixing block through a right grid plate suction cavity fixing bolt hole and a bolt, and a right grid plate suction cavity upper flange and a right grid plate suction cavity lower flange are symmetrically arranged on the right grid plate suction cavity 9 and are connected with an end wall suction cavity pressure stabilizing box right throttle valve 36 arranged on the end wall suction cavity pressure stabilizing box 31 through a pipeline.
The left inflow boundary layer suction cavity 4 is fixed on the left rotary table 2 through a left inflow boundary layer suction cavity fixing bolt hole 27 and a bolt, a left inflow boundary layer suction cavity upper side flange 26 and a left inflow boundary layer suction cavity lower side flange 30 are symmetrically arranged on the left inflow boundary layer suction cavity 4, and are connected with a boundary layer suction cavity pressure stabilizing box left side throttle valve 40 on a boundary layer suction cavity pressure stabilizing box 37 through pipelines. Similarly, the right inflow boundary layer suction cavity is fixed on the right turntable 8 through a right inflow boundary layer suction cavity fixing bolt hole and a bolt, and a right inflow boundary layer suction cavity upper side flange and a right inflow boundary layer suction cavity lower side flange are symmetrically arranged on two sides of the right inflow boundary layer suction cavity and are connected with a boundary layer suction cavity pressure stabilizing box right side throttle valve 42 arranged on the boundary layer suction cavity pressure stabilizing box 37 through a pipeline.
An end wall suction cavity pressure stabilizing box flange 32, an end wall suction cavity pressure stabilizing box left side throttle valve 33, an end wall suction cavity pressure stabilizing box left side pressure measuring probe 34, an end wall suction cavity pressure stabilizing box right side pressure measuring probe 35 and an end wall suction cavity pressure stabilizing box right side throttle valve 36 are arranged on the end wall suction cavity pressure stabilizing box 31, the end wall suction cavity pressure stabilizing box flange 32 is arranged at the top of the end wall suction cavity pressure stabilizing box 31 and is connected with a pipeline of a vacuum pump II, the end wall suction cavity pressure stabilizing box left side throttle valve 33 and the end wall suction cavity pressure stabilizing box left side pressure measuring probe 34 are sequentially arranged on the left side pipeline from left to right, and the end wall suction cavity pressure stabilizing box right side throttle valve 36 and the end wall suction cavity pressure stabilizing box right side pressure measuring. The left pressure probe 34 of the end wall suction cavity pressure stabilizing box and the right pressure probe 35 of the end wall suction cavity pressure stabilizing box are identical in structure and symmetrically arranged, are connected to a testing system through pneumatic pipelines, convert collected pressure signals into electric signals through a signal converter, feed the electric signals back to a computer, calculate suction flow, and control the symmetry of the left and right suction flow through a left throttle valve of the wall suction cavity pressure stabilizing box and a right throttle valve 36 of the end wall suction cavity pressure stabilizing box. The testing system is an existing mechanism and mainly comprises a pressure scanning valve, a computer and the like, wherein a pressure signal measured by a probe is converted into an electric signal through the pressure scanning valve and then fed back to the computer, the electric signal is converted into the air flow velocity of the position where the probe is located through the computer, and then the suction flow is calculated according to the cross section area of a pipeline.
The boundary layer suction cavity pressure stabilizing box 37 is provided with a boundary layer suction cavity pressure stabilizing box flange 38, a boundary layer suction cavity pressure stabilizing box left side pressure measuring probe 39, a boundary layer suction cavity pressure stabilizing box left side throttle valve 40, a boundary layer suction cavity pressure stabilizing box right side pressure measuring probe 41 and a boundary layer suction cavity pressure stabilizing box right side throttle valve 42, the boundary layer suction cavity pressure stabilizing box flange 38 is arranged at the top of the boundary layer suction cavity pressure stabilizing box 37 and is connected with a pipeline of a vacuum pump III, the boundary layer suction cavity pressure stabilizing box left side throttle valve 40 and the boundary layer suction cavity pressure stabilizing box left side pressure measuring probe 39 are sequentially arranged on a left side pipeline from left to right, and the boundary layer suction cavity pressure stabilizing box right side throttle valve 42 and the boundary layer suction cavity pressure measuring probe 41 with the same structure are symmetrically arranged on a right side pipeline. The left pressure probe 39 of the boundary layer suction cavity pressure stabilizing box and the right pressure probe 41 of the boundary layer suction cavity pressure stabilizing box are identical in structure and are symmetrically arranged, the probes are connected to a test system through pneumatic pipelines, collected pressure signals are converted into electric signals through a signal converter and then fed back to a computer, the suction flow can be calculated, and the left and right suction flow symmetry can be controlled through a left throttle valve 40 of the boundary layer suction cavity pressure stabilizing box and a right throttle valve 42 of the boundary layer suction cavity pressure stabilizing box. The left side pressure measuring probe 39 and the right side pressure measuring probe 41 of the boundary layer suction cavity pressure stabilizing box on the left side and the right side can ensure the symmetry of the left side and the right side suction flow.
Example 2
The left side grid plate front edge suction slit 13 and the right side grid plate front edge suction slit with different structures and quantities can be arranged according to the specific requirements of experimental conditions, and the left side grid plate front edge suction slit 13 and the right side grid plate front edge suction slit with different lengths, widths, quantities and quantities can be arranged according to the specific requirements.
In this embodiment, the range of lengths for the left and right louver leading edge suction slots 13 and 13 may be designed to exclude intermediate blades if the blade-cascade intermediate blades have good periodicity, as shown in FIG. 11, according to the computational fluid dynamics CFD calculation structure.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A combined pumping system for improving planar cascade periodicity and outlet flow field quality, comprising: the device comprises an upper end wall suction cavity (1), a left rotary table (2), a left rotary table slideway (5), a cascade wind tunnel experiment table (6), a cascade wind tunnel experiment table fixing seat (7), a right rotary table (8) and a right rotary table slideway;
the left turntable (2) and the right turntable (8) are identical in structure and symmetrically arranged and are respectively in rotating connection with the left turntable slideway (5) and the right turntable slideway; the left turntable slideway (5) and the right turntable slideway have the same structure and are symmetrically arranged on the cascade wind tunnel experiment table (6); the upper end wall suction cavity (1) is arranged on the cascade wind tunnel experiment table (6), and the upper end of the upper end wall suction cavity is provided with an upper end wall suction cavity suction hole (21); the cascade wind tunnel experiment table (6) is arranged on the fixed seat (7) of the cascade wind tunnel experiment table, and a hollow cavity structure is arranged inside the cascade wind tunnel experiment table (6);
the left turntable (2) is provided with a left grid plate fixing block (10), a left grid plate (11) and a left inflow boundary layer suction seam (12), the left grid plate (11) is fixedly connected with the left grid plate fixing block (10), and the left inflow boundary layer suction seam (12) is arranged below the left grid plate fixing block (10) and is provided with at least one suction seam;
the right turntable (8) is provided with a right grid plate fixing block, a right grid plate (16) and a right inflow boundary layer suction seam, and the right grid plate fixing block and the left grid plate fixing block (10) are same in structure and are symmetrically arranged; the right grid plate (16) is fixedly connected with the right grid plate fixing block, has the same structure as the left grid plate (11), and is symmetrically arranged; the right inflow boundary layer suction slits are arranged below the right grid plate fixing block, have the same structure as the left inflow boundary layer suction slits (12), are equal in number and are symmetrically arranged;
a hollow cavity communicated with the hollow cavity structure is formed between the left rotary table (2) and the right rotary table (8), a testing blade device is installed in the hollow cavity, and two sides of the testing blade device are fixed through testing blade fixing holes (14) which are symmetrically arranged on the left grid plate (11) and the right grid plate (16) and have the same structure; the front side and the rear side of the testing blade device are respectively in contact connection with an upper guide plate (18) and a lower guide plate (19), and the upper guide plate (18) and the lower guide plate (19) are both arranged in a space region where the hollow cavity chamber is communicated with the hollow cavity structure;
the outer wall surface of the left rotary table (2) is provided with a left incoming flow boundary layer suction cavity (4) communicated with a boundary layer suction cavity pressure stabilizing box (37), a hollow cavity I is arranged inside the left rotary table and communicated with the left incoming flow boundary layer suction seam (12), and the left incoming flow boundary layer suction seam (12) is communicated with the hollow cavity;
a right incoming flow boundary layer suction cavity communicated with a boundary layer suction cavity pressure stabilizing box (37) is arranged on the outer wall surface of the right rotary disc (8), the right incoming flow boundary layer suction cavity and the left incoming flow boundary layer suction cavity (4) are same in structure and symmetrically arranged, a hollow cavity II is arranged inside and communicated with the right incoming flow boundary layer suction seam, and the right incoming flow boundary layer suction seam is communicated with the hollow cavity;
the testing blade device is composed of a row of a plurality of testing blades (20), a group of testing blade suction surface suction hole structures with the same structure are symmetrically arranged on two sides of the back surface of each testing blade (20), and the testing blade suction surface suction hole structures on two sides are respectively arranged on the left grid plate (11) and the right grid plate (16) and are symmetrically distributed; the uppermost test blade (20) is connected to the upper end wall suction chamber (1);
the outer wall surface of the left grid plate fixing block (10) is provided with a left grid plate suction cavity (3) communicated with the end wall suction cavity pressure stabilizing box (31), a hollow cavity III is arranged inside the left grid plate suction cavity, and the left grid plate suction cavity is communicated with the hollow cavity through the suction hole structure of the suction surface of the test blade;
the outer wall surface of the right side grid plate fixing block is provided with a right side grid plate suction cavity (9) communicated with an end wall suction cavity pressure stabilizing box (31), the right side grid plate suction cavity (9) and the left side grid plate suction cavity (3) are same in structure and symmetrically arranged, a hollow cavity IV is arranged inside the right side grid plate suction cavity and communicated with the hollow cavity through the suction hole structure of the suction surface of the test blade.
2. A combined pumping system for improving the periodicity of the planar cascade and the quality of the exit flow field according to claim 1, characterized in that the uppermost test vane (20) of the test vane arrangement is a suction-perforated test vane (17) whose leading edge is in contact connection with the upper deflector (18);
the test blades (17) with the suction holes are communicated with the suction holes (21) of the suction cavity of the upper end wall in a one-to-one correspondence mode through pipelines, the number of the suction holes (21) of the suction cavity of the upper end wall can be adjusted according to the requirement in the experimental process, the suction position of the suction holes (21) of the suction cavity of the upper end wall is adjusted under the condition of different cascade attack angles, the accumulation of low-energy fluid clusters near the upper end wall of the cascade is reduced, the flow field quality of the outlet of the planar cascade is adjusted efficiently, energy is saved accurately, and the periodicity of the cascade is improved;
the test blade (20) at the lowest position in the test blade device is in contact connection with the lower guide plate (19) to play a role of closing the lower end wall of the blade cascade and reducing airflow leakage of the lower end wall of the blade cascade, so that airflow close to the lower end wall flows out of the blade cascade along the pressure surface side of the test blade (20) at the lowest position in the test blade device;
the test blade (20) may be a compressor blade or a turbine blade.
3. The combined suction system for improving the periodicity of the planar blade cascade and the quality of the outlet flow field according to claim 1 or 2, characterized in that the left side grid plate (11) is provided with at least one left side grid plate front edge suction slit (13) which is positioned below the suction hole structure of the suction surface of the test blade and at the front edge position of the test blade device, so as to further reduce the thickness of the boundary layer of the blade cascade and reduce the influence caused by the boundary layer; the seam opening direction of the front edge suction seam (13) of the left grid plate is parallel to the central axis of the seam opening direction of the suction seam (12) of the left inflow boundary layer, and in order to ensure the suction capacity of the end wall, the widths of the front edge suction seam (13) of the left grid plate and the suction seam (12) of the left inflow boundary layer are both smaller than or equal to the diameter of the suction hole (15) of the suction surface of the test blade;
the right grid plate (16) is symmetrically provided with right grid plate front edge suction slits which have the same structure and the same number as the left grid plate front edge suction slits (13).
4. The combined suction system for improving the periodicity of the planar blade cascade and the quality of the outlet flow field according to claim 1 or 2, wherein the bottom of the upper end wall suction cavity (1) is fixed on one side of the top of the blade cascade wind tunnel experiment table (6) through an upper end wall suction cavity fixing bolt hole (24), a hollow cavity V communicated with the upper end wall suction cavity suction hole (21) is formed inside the upper end wall suction cavity left flange (22) and upper end wall suction cavity.
5. A combined suction system for improving the periodicity of the planar cascade and the quality of the outlet flow field according to claim 1 or 2, characterised in that each group of test blade suction surface suction hole structures consists of a plurality of test blade suction surface suction holes (15), the centre line of each group of test blade suction surface suction hole structures being obtained by offsetting the blade suction surface side profile lines, enabling better adherence to the suction surface, resulting in better suction effect.
6. The combined pumping system for improving the periodicity of the planar cascade and the quality of the outlet flow field according to claim 5, characterized in that the suction holes (15) of the suction surface of the test blades are threaded holes, and the suction holes (15) of the suction surface of the test blades are blocked by flat head screws under the pumping condition, and simultaneously, the inner surfaces of the left grid plate (11) and the right grid plate (16) are ensured to be smooth and flat without generating bulges and pits; and adjusting the number of the suction holes (15) of the suction surface of the test blade according to the numerical settlement results under different attack angles, so that the suction effect is more obvious, and the density flow ratio of the flow field at the outlet of the blade cascade is reduced.
7. The combined suction system for improving the periodicity of the plane blade cascade and the quality of the outlet flow field as claimed in claim 1, wherein the left side grid plate suction cavity (3) is fixed on the left side grid plate fixing block (10) through a left side grid plate suction cavity fixing bolt hole (28), a left side grid plate suction cavity upper side flange (25) and a left side grid plate suction cavity lower side flange (29) are symmetrically arranged on two sides of the left side grid plate suction cavity (3), and are connected with an end wall suction cavity pressure stabilizing box left side throttle valve (33) arranged on the end wall suction cavity pressure stabilizing box (31) through a pipeline;
the right side grid plate suction cavity (9) is fixed on the right side grid plate fixing block through a right side grid plate suction cavity fixing bolt hole, a right side grid plate suction cavity upper side flange and a right side grid plate suction cavity lower side flange are symmetrically arranged on two sides of the right side grid plate suction cavity (9) and are connected with an end wall suction cavity pressure stabilizing box right side throttle valve (36) arranged on the end wall suction cavity pressure stabilizing box (31) through a pipeline.
8. The combined suction system for improving the periodicity of the plane blade cascade and the quality of the outlet flow field according to claim 1 or 7, characterized in that an end wall suction cavity pressure stabilizing box flange (32) is arranged at the top of the end wall suction cavity pressure stabilizing box (31), an end wall suction cavity pressure stabilizing box left throttle valve (33) and an end wall suction cavity pressure stabilizing box left pressure measuring probe (34) are sequentially arranged on a left pipeline from left to right, and an end wall suction cavity pressure stabilizing box right throttle valve (36) and an end wall suction cavity pressure stabilizing box right pressure measuring probe (35) which are identical in structure are symmetrically arranged on a right pipeline;
the left pressure probe (34) of the end wall suction cavity pressure stabilizing box and the right pressure probe (35) of the end wall suction cavity pressure stabilizing box are identical in structure and symmetrically arranged, and are connected to a test system through pneumatic pipelines, collected pressure signals are converted into electric signals through a signal converter and then fed back to a computer, the suction flow at the position can be calculated, and the left and right suction flows are controlled to be symmetrical through the left throttle valve (36) of the wall suction cavity pressure stabilizing box and the right throttle valve (36) of the end wall suction cavity pressure stabilizing box.
9. The combined suction system for improving the periodicity of the plane blade cascade and the quality of the outlet flow field according to claim 1, wherein the left incoming flow boundary layer suction cavity (4) is fixed on the left rotary table (2) through a left incoming flow boundary layer suction cavity fixing bolt hole (27), a left incoming flow boundary layer suction cavity upper side flange (26) and a left incoming flow boundary layer suction cavity lower side flange (30) are symmetrically arranged on two sides of the left incoming flow boundary layer suction cavity (4) and are connected with a boundary layer suction cavity pressure stabilizing box left side throttle valve (40) arranged on the boundary layer suction cavity pressure stabilizing box (37) through a pipeline;
the right incoming flow boundary layer suction cavity is fixed on the right turntable (8) through a right incoming flow boundary layer suction cavity fixing bolt hole, a right incoming flow boundary layer suction cavity upper side flange and a right incoming flow boundary layer suction cavity lower side flange are symmetrically arranged on two sides of the right incoming flow boundary layer suction cavity and are connected with a boundary layer suction cavity pressure stabilizing box right side throttle valve (42) arranged on a boundary layer suction cavity pressure stabilizing box (37) through a pipeline.
10. The combined suction system for improving the periodicity of the planar cascade and the quality of the outlet flow field according to claim 1 or 9, wherein a boundary layer suction cavity pressure stabilizing box flange (38) is arranged at the top of the boundary layer suction cavity pressure stabilizing box (37), a boundary layer suction cavity pressure stabilizing box left throttle valve (40) and a boundary layer suction cavity pressure stabilizing box left pressure measuring probe (39) are sequentially arranged on a left pipeline from left to right, and a boundary layer suction cavity pressure stabilizing box right throttle valve (42) and a boundary layer suction cavity pressure stabilizing box right pressure measuring probe (41) which are identical in structure are symmetrically arranged on a right pipeline;
the left side pressure probe (39) of the boundary layer suction cavity pressure stabilizing box and the right side pressure probe (41) of the boundary layer suction cavity pressure stabilizing box are identical in structure and symmetrically arranged, and are connected to a test system through pneumatic pipelines, collected pressure signals are converted into electric signals through a signal converter and then fed back to a computer, the suction flow at the position can be calculated, the left side and the right side of the suction flow are controlled through a boundary layer suction cavity pressure stabilizing box left side throttling valve (40) and a boundary layer suction cavity pressure stabilizing box right side throttling valve (42), and the left side and the right side of the suction flow are symmetrical through the boundary layer suction cavity pressure stabilizing box left side pressure probe (39) and the boundary layer suction cavity pressure stabilizing box right side pressure probe (41).
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