Cascade experiment device and method for cascade front edge partial string small blade adjustable compressor

Abstract

The application discloses a cascade front edge partial serial small blade adjustable compressor cascade experiment device and method, and belongs to the field of turbomachinery experiments.The device comprises an upper cascade plate, a lower cascade plate, a fixed distance column and a small blade mounting module.The upper cascade plate and the lower cascade plate are arranged in parallel and are connected into an integrated body through the fixed distance column arranged in the circumferential direction, and a cascade assembly is arranged between the upper cascade plate and the lower cascade plate.The small blade mounting module is arranged on the lower cascade plate and is located at the front edge of the cascade assembly, is used for mounting the front edge small blade of the main blade serial in the cascade assembly, and can adjust the axial and circumferential positions of the front edge small blade and the inlet angle of the small blade.The experiment device is convenient for mounting, dismounting and fixing of the front edge small blade, and effectively saves the processing cost.

Description

Technical Field

[0001] This invention belongs to the field of turbomachinery experiments, specifically relating to an experimental device and method for compressor blade cascades with adjustable locally tandem blades at the leading edge of the blade cascade. Background Technology

[0002] Compressors, as a crucial component of turbomachinery, are widely used in aerospace, energy, and chemical industries. With the continuous improvement of single-stage pressure ratio and efficiency in compressors, the adverse pressure gradient within the compressor channel is also increasing, leading to greater boundary layer separation losses and secondary flow losses. Therefore, with the increasing load on compressor blades, designing new blade structures and developing flow control technologies are of great significance for improving compressor performance and expanding the compressor's stable operating margin.

[0003] Advanced flow control methods should achieve optimal control effects with minimal or no energy consumption. One effective way to improve the aerodynamic performance of compressor blades is to use a vortex generator (VG). A VG induces vortex momentum in the airflow, causing the laminar boundary layer near the wall to transition to a turbulent boundary layer earlier, thereby improving the fluid's resistance to separation within the boundary layer. This device is not only simple in structure and easy to design, but also highly reliable and suitable for various operating conditions, thus it is widely used in compressors. Existing technologies disclose that the introduction of a VG structure facilitates the movement of the stall boundary of the blade cascade towards higher angles of attack, and that the induced vortices generated by the VG help reduce separation losses in the middle of the blade cascade.

[0004] Another way to control flow separation within the compressor is to use tandem blades. Tandem blades are a combination of two closely spaced rows of blades. After the high-energy incoming flow is accelerated by the converging gap between the front and rear blades, it is ejected along the suction surface of the rear blade. On the one hand, it blows away the low-energy fluid in the wake of the front blade, and on the other hand, it causes the boundary layer to regenerate at the leading edge of the rear blade. Therefore, tandem blades can support greater aerodynamic loads without causing excessive aerodynamic losses. In the literature Xiang Honghui, Ge Ning, Hou Minjie, et al. Performance comparison test of single-row blade cascade versus tandem blade cascade at high incoming Mach number [J]. Journal of Aerospace Power, 2016, 31(11):2757-2764, Xiang Honghui et al. conducted a performance comparison test of single-row blade cascade and tandem blade cascade at high incoming Mach number. The results showed that, compared with single-row blade cascade, tandem blade cascade can significantly reduce flow losses and increase pressure ratio under design conditions.

[0005] However, based on the existing technology, the induced vortices generated by the vortex generator cannot control the flow over a large blade span. Furthermore, the wake flow generated by tandem blades, due to their two rows of blades, creates complex unsteady interference with the intake conditions of the downstream blade row. Simultaneously, the acceleration effect of tandem blades is limited, making it impossible to effectively control the separation flow at the trailing edge of the suction surface of the trailing blade. Therefore, to improve interstage matching and further control the trailing edge separation flow, a structure is proposed where the leading-edge blades act as vortex generators, generating a local tandem flow with the leading edge of the main blade. However, existing compressor blade cascade experimental devices face numerous difficulties in adjusting the axial and circumferential positions, intake angle, and blade height of the leading-edge blades, making it impossible to meet the requirements of this structure. Therefore, experiments with locally tandem blades at the leading edge of the cascade cannot be conducted. Summary of the Invention

[0006] The technical problem to be solved:

[0007] To overcome the shortcomings of existing technologies, this invention provides an experimental apparatus for compressor blade cascades with adjustable tandem leading-edge blades. This apparatus achieves circumferential and axial movement of the leading-edge blades by moving a slider, a circumferential position adjustment block, and an axial position adjustment block in the front groove of the lower cascade plate; adjusts the inlet angle of the leading-edge blades by rotating the leading-edge blade mounting block; and allows the height of the leading-edge blades to be customized according to different experimental requirements, thus addressing the lack of experimental data in existing technologies regarding the influence of locally tandem leading-edge blades on the cascade flow field.

[0008] The technical solution of the present invention is: a compressor blade cascade experimental device with adjustable tandem blades at the leading edge of the blade cascade, characterized in that: it includes an upper cascade plate, a lower cascade plate, a spacer column and a blade mounting module, wherein the upper cascade plate and the lower cascade plate are arranged in parallel and opposite to each other, and are connected into one unit by a spacer column arranged along the circumferential direction, and the blade cascade assembly is installed between the upper and lower cascade plates;

[0009] The leaflet mounting module is disposed on the lower grid plate and located at the leading edge of the blade assembly. It is used to install the leading edge leaflets that are arranged in series with the main blades in the blade assembly, and can adjust the axial and circumferential positions of the leading edge leaflets, as well as the air intake angle of the leaflets.

[0010] A further technical solution of the present invention is: the leaflet mounting module includes a slider, a circumferential position adjustment block, an axial position adjustment block, and a leading edge leaflet mounting block; the slider is installed in the mounting groove at the leading edge of the lower grid plate, and has multiple insertion holes along the length direction, each insertion hole corresponding to the leading edge of each main blade in the blade assembly; the multiple leading edge leaflets are rotatably mounted in each insertion hole through the leading edge leaflet mounting block;

[0011] The circumferential position adjustment block is disposed in the circumferential gap between the slider and the mounting groove, and is used to adjust the circumferential position of the leading edge leaflet relative to the main blade; the axial position adjustment block is disposed in the axial gap between the slider and the mounting groove, and is used to adjust the axial position of the leading edge leaflet relative to the main blade.

[0012] A further technical solution of the present invention is as follows: the upper end of the leading edge leaflet mounting block is a leading edge leaflet mounting seat, and the lower end is a fixing rod; the leading edge leaflet mounting seat has a leading edge leaflet mounting hole and a circumferential scale is engraved on its upper surface to accurately adjust the air intake angle of the leading edge leaflet; the fixing rod has an external thread, is inserted into the insertion hole of the slider, and is fixed in position by a nut.

[0013] A further technical solution of the present invention is: the spacing between the upper grid plate and the lower grid plate is adjustable, and multiple blade mounting through holes are evenly distributed on each of them; a front groove is opened at the front edge of the lower grid plate, and a slider, a circumferential position adjustment block and an axial position adjustment block are installed in the front groove, and the outer groove opening is sealed by a baffle to restrict and fix the position of the slider, the circumferential position adjustment block and the axial position adjustment block inside.

[0014] A further technical solution of the present invention is as follows: the slider is a long strip structure with equally spaced insertion holes on it; the circumferential position adjustment block is rectangular and is disposed on the short side of the slider; the axial position adjustment block is strip-shaped and is disposed on the long side of the slider, and the number and size of the two types of adjustment blocks are designed according to actual needs.

[0015] A method for adjusting a compressor blade cascade experimental apparatus with adjustable tandem blades at the leading edge, characterized in that:

[0016] When it is necessary to adjust the circumferential position of the leading edge leaflet, change the number of circumferential position adjustment blocks on both sides of the slider, or replace the circumferential position adjustment blocks of different sizes.

[0017] When it is necessary to adjust the axial position of the leading edge leaflet, change the number of axial position adjustment blocks on both sides of the slider, or replace the axial position adjustment blocks of different sizes.

[0018] When it is necessary to adjust the leading edge lobes intake angle, tighten the mounting angle of the leading edge lobes mounting block.

[0019] Beneficial effects

[0020] The beneficial effects of this invention are as follows: This invention can achieve independent adjustment of the axial and circumferential positions, height and inlet angle of the leading edge leaflets in a set of blade cascade test pieces, so as to study the influence of the above four parameters on the control effect of the leading edge leaflets. Compared with traditional blade cascade test pieces, it can significantly save the production cost and assembly time of the test pieces, which is conducive to the progress of experimental research on the local tandem leaflets at the leading edge, so as to further realize the control of internal flow separation of the compressor.

[0021] This invention utilizes components such as a leading-edge blade mounting block, a slider, a circumferential position adjustment block, an axial position adjustment block, and a baffle to adjust the position and mounting angle of the leading-edge blade. It is applicable to leading-edge blades of different heights, addressing the shortcomings of existing technologies in experimental research on locally tandem leading-edge blades and the installation problems of leading-edge blades in inline blade cascades. By adjusting the positions of the circumferential and axial position adjustment blocks and the slider, the axial and circumferential positions of the leading-edge blade relative to the blade cascade assembly are adjusted to study the influence of different axial and circumferential positions on the flow control effect of the blade. Adjusting the leading-edge blade mounting block adjusts the inlet angle of the leading-edge blade, thereby studying the influence of the blade's incoming flow angle on its flow separation capability. The leading-edge blade is mounted in the slider by the mounting block, and the blade height can be customized according to actual experimental needs to analyze the flow control capability of the blade at different heights.

[0022] The experimental apparatus proposed in this invention facilitates the installation, disassembly, and fixation of the leading edge leaflet, effectively saving processing costs. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the experimental apparatus of the present invention;

[0024] Figure 2 This is a structural schematic diagram of the upper grid plate, where a is an isometric view, b is a top view, and c is a schematic diagram of section AA.

[0025] Figure 3 This is a structural schematic diagram of the lower grid plate, where a is an isometric view, b is a top view, c is a front view, and d is a schematic diagram of section AA.

[0026] Figure 4 This is a schematic diagram of the slider structure, where a is an isometric view, b is a top view, c is a bottom view, d is a cross-sectional view of AA, and e is a cross-sectional view of BB.

[0027] Figure 5 This is a schematic diagram of the circumferential position adjustment block;

[0028] Figure 6 This is a schematic diagram of the axial position adjustment block;

[0029] Figure 7 This is a structural schematic diagram of the leading leaflet, where a is an isometric view and b is a left view with dimensions labeled.

[0030] Figure 8 This is a structural schematic diagram of the leading edge leaflet mounting block, where a is an isometric view, b is a top view, and c is a front view;

[0031] Figure 9 This is a schematic diagram of the baffle structure;

[0032] Figure 10 yes Figure 1 A schematic diagram of a horizontal cross-section, where a is a front view of the experimental setup, b is a schematic diagram of the AA cross-section, and c is a schematic diagram of the BB cross-section.

[0033] Figure 11 yes Figure 1 Schematic diagram of longitudinal section, where a is the bottom view of the experimental setup, b is the schematic diagram of section AA, and c is the schematic diagram of section BB.

[0034] Explanation of reference numerals in the attached drawings: 1—Upper grid plate; 2—Lower grid plate; 3—Spacing post; 4—Blade assembly; 5—Blade mounting through hole; 6—Spacing post mounting through hole; 7—Slider; 8—Insertion hole; 9—Circumferential position adjustment block; 10—Axial position adjustment block; 11—Leading edge leaflet; 12—Leading edge leaflet mounting block; 13—Leading edge leaflet mounting hole; 14—Leading edge leaflet mounting seat; 15—Fixing rod; 16—Baffle; 17—Baffle fixing hole; 18—Threaded through hole for set screw of lower grid plate front groove; 19—Pressure measuring blade; 20—Static pressure hole on blade surface. Detailed Implementation

[0035] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0036] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] This embodiment is an experimental device for compressor blade cascades with adjustable leading edge tandem leaflets, including a cascade plate, a blade cascade assembly 4, and a spacer post 3; the cascade plate includes an upper cascade plate 1 and a lower cascade plate 2, and the cascade plate has a spacer post mounting through hole 6; the lower end of the spacer post 3 is mounted on the upper surface of the lower cascade plate 2, and the upper cascade plate 1 is mounted on the upper end face of the spacer post 3; it also includes a slider 7, seven circumferential position adjustment blocks 9, two axial position adjustment blocks 10, three leading edge leaflet mounting blocks 12, three leading edge leaflets 11, and a baffle 16.

[0038] The upper grid plate 1 and the lower grid plate 2 are parallel and the spacing is adjustable, with multiple blade mounting through holes 5 evenly distributed; the lower grid plate 2 has a front groove for mounting the slider 7, the circumferential position adjustment block 9, the axial position adjustment block 10 and the baffle 16.

[0039] The slider 7 is placed in the front groove of the lower grid plate 2, positioned by multiple circumferential position adjustment blocks 9, and fixed by baffle 16. Multiple insertion holes 8 are opened on the slider 7 for installing the leading edge leaf mounting block 12.

[0040] The circumferential position adjustment block 9 is rectangular, and the axial position adjustment block 10 is strip-shaped. Their dimensions, shape, and quantity can be customized according to specific experimental requirements. By adjusting the positions of the circumferential and axial position adjustment blocks and the slider, the axial and circumferential positions of the leading-edge leaflet relative to the blade assembly can be adjusted to study the influence of different axial and circumferential positions on the flow control effect of the leaflet.

[0041] The leading edge leaflet mounting block 12 consists of a leading edge leaflet mounting seat 14 and a fixing rod 15. The leading edge leaflet mounting seat 14 has a leading edge leaflet mounting hole 13, and a scale is drawn around its upper surface to accurately adjust the air intake angle of the leading edge leaflet 11. The fixing rod 15 is threaded. According to the specific experimental requirements, the nut can be loosened to adjust the air intake angle of the leading edge leaflet, thereby studying the influence of the leaflet's incoming flow angle on its ability to control flow separation.

[0042] The leading edge leaflet mounting block 12 is fixed in the insertion hole 8 of the slider 7 by a nut. The position of the leading edge leaflet 11 relative to the blade assembly 4 can be adjusted by adjusting the positions of the slider 7, the circumferential position adjusting block 9, and the axial position adjusting block 10. The height of the leaflet can be processed according to the actual experimental needs to analyze the flow control capability of the leaflet at different heights.

[0043] The baffle 16 has a baffle fixing hole 17. After the positions of the slider and the circumferential and axial position adjustment blocks are fixed, the screws are inserted into the fixing hole and the set screws in the front groove of the lower grid plate and tightened to achieve fixation.

[0044] In this embodiment, the upper grid plate 1 has a length L1 = 160mm, a width W1 = 30mm, and a thickness H1 = 7mm; the lower grid plate 2 has a front groove on the basis of the upper grid plate 1, with a length L2 = 88mm, a width W2 = 7mm, and a depth H2 = 7mm; the height of the mounting bracket composed of the upper and lower grid plates is H3 = 66mm.

[0045] The blade assembly 4 has a height H4 = 60 mm and a chord length L3 = 20 mm. The blade assembly 4 includes a pressure measuring blade 19, with static pressure holes 20 evenly opened on the suction and pressure surfaces of the blade. During the experiment, the blade assembly 4 is installed on the mounting bracket composed of the grid plate and the spacer column 3, with the portion inserted into the upper and lower grid plates each being 4 mm. The blade installation angle is 32° and the grid pitch is 22 mm.

[0046] The slider 7 has a length L4 = 66mm, a width W3 = 4mm, and a depth H5 = 6mm; a groove is provided at the bottom of the slider 7 to facilitate the removal of the nut to adjust the air intake angle of the leading edge leaflet 11.

[0047] The circumferential position adjustment block 9 is rectangular in shape, with a length L5 = 1 mm, a width W4 = 4 mm, and a height H6 = 7 mm;

[0048] The axial position adjustment block 10 is rectangular strip with a length L6 = 80 mm, a width W5 = 1 mm, and a height H7 = 7 mm.

[0049] The height H8 of the leading edge leaflet 11 is 7mm, the chord length L7 is 2mm, and the portion of the leading edge leaflet 11 inserted into the leading edge leaflet mounting base 14 is 2mm.

[0050] The leading edge leaflet mounting block 12 has a length L8 = 6 mm, the leading edge leaflet mounting seat 14 has a diameter D1 = 3 mm, a length L9 = 2 mm, and a length L10 = 4 mm for the fixing rod 15.

[0051] The baffle 16 is strip-shaped, with a length L11 = 88 mm, a width W6 = 1 mm, and a height H9 = 7 mm;

[0052] In this embodiment, the leading edge leaflet mounting block 12 consists of a leading edge leaflet mounting seat 14 and a fixing rod 15. The leading edge leaflets are placed in the leading edge leaflet mounting holes 13 on each mounting block 12. The leading edge leaflet mounting block 12 is installed in the corresponding insertion hole 8 on the slider 7. The nut is passed through the fixing rod 15 below the leading edge leaflet mounting block 12 and tightened to fix the leading edge leaflet 11 on the slider 7. When the experiment requires adjustment of the air intake angle of the leading edge leaflet 11, a scale is drawn on the upper surface of the leading edge leaflet mounting seat 14. According to the specific actual needs, the nut is loosened and the mounting angle of the leading edge leaflet 11 is adjusted. The adjusted slider 7 is placed in a suitable circumferential position, and then the baffle 16 is installed. The set screw is passed through the fixing hole of the baffle 16 and the threaded through hole 18 of the set screw of the lower grid plate front groove to achieve fixation. To readjust the circumferential position of the leading edge leaflet 11, loosen the set screw, remove the baffle 16, move the relative positions of the slider 7 and the circumferential position adjusting block 9, then reinstall the baffle 16 and tighten the screw. To readjust the axial position of the leading edge leaflet 11, loosen the set screw, remove the baffle 16, move the slider 7, the circumferential position adjusting block 9, and the axial position adjusting block 10, then reinstall the baffle 16 and tighten the screw.

[0053] The compressor blade cascade structure with adjustable tandem leading-edge blades in this embodiment includes a main blade and leading-edge blades, with the leading-edge blades located on the suction side of the main blade. The trailing edge of the pressure surface of the leading-edge blade forms a converging gap channel with the leading edge of the suction surface of the main blade, and the inlet angle of the leading-edge blade is adjustable. The structural parameters of the leading-edge blades can be autonomously adjusted to obtain the optimal geometric and positional parameters for control.

[0054] The specific parameter limitations are as follows:

[0055] The axial position of the leading edge leaflet relative to the main leaflet should be within the range of -10% to 10%. If the value is too large or too small, the acceleration effect of the slit channel on the airflow will be unsatisfactory.

[0056] The circumferential position of the leading edge leaflet relative to the main leaflet mainly affects the convergence of the slit channel. A smaller circumferential distance is beneficial to airflow acceleration. Therefore, the value of the circumferential position should be in the range of 0-10%.

[0057] The difference between the leading edge leaflet inlet angle and the main blade inlet angle affects the acceleration effect of the convergence channel on the airflow. In order to ensure that the acceleration effect is good enough, the difference between the inlet angles is adjustable and decreases as the angle of attack of the incoming flow increases.

[0058] The axial chord length of the leading edge leaflet relative to the main leaflet primarily affects the intensity of the induced eddy current. The value of the relative axial chord length 8 should be within the range of 10%-20%.

[0059] The value of the blade span height of the leading edge leaflet relative to the main blade needs to be considered from multiple aspects. On the one hand, the blade span height affects the magnitude of the leaflet's shape loss; on the other hand, the blade span height determines the spanwise position of the induced vortex, which should be located in the region where angular separation is fully developed. Generally speaking, the blade span height should be around 10%.

[0060] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. An experimental apparatus for compressor blade cascades with adjustable tandem blades at the leading edge, characterized in that: It includes an upper grid plate, a lower grid plate, a spacer post, and a leaflet mounting module. The upper and lower grid plates are arranged in parallel and opposite directions and are connected as a whole by a spacer post arranged along the circumferential direction. The leaflet assembly is installed between the upper and lower grid plates. The leaflet mounting module is disposed on the lower grid plate and located at the leading edge of the blade assembly. It is used to install the leading edge leaflets that are arranged in series with the main blades in the blade assembly, and can adjust the axial and circumferential positions of the leading edge leaflets, as well as the air intake angle of the leaflets. The leaflet mounting module includes a slider, a circumferential position adjustment block, an axial position adjustment block, and a leading edge leaflet mounting block; the slider is installed in the mounting groove at the leading edge of the lower grid plate, and has multiple insertion holes along its length, each insertion hole corresponding to the leading edge of each main blade in the blade assembly; the multiple leading edge leaflets are rotatably mounted in their respective insertion holes via the leading edge leaflet mounting block. The circumferential position adjustment block is disposed in the circumferential gap between the slider and the mounting groove, and is used to adjust the circumferential position of the leading edge leaflet relative to the main blade; the axial position adjustment block is disposed in the axial gap between the slider and the mounting groove, and is used to adjust the axial position of the leading edge leaflet relative to the main blade. The upper end of the leading edge leaflet mounting block is a leading edge leaflet mounting seat, and the lower end is a fixing rod; the leading edge leaflet mounting seat has a leading edge leaflet mounting hole and a circumferential scale is engraved on its upper surface to accurately adjust the air intake angle of the leading edge leaflet; the fixing rod has an external thread, is inserted into the insertion hole of the slider, and is fixed in position by a nut.

2. The compressor blade cascade experimental apparatus with adjustable tandem blades at the leading edge as described in claim 1, characterized in that: The spacing between the upper and lower grid plates is adjustable, and multiple blade mounting through holes are evenly distributed on each plate. A front groove is opened at the front edge of the lower grid plate, and a slider, a circumferential position adjustment block, and an axial position adjustment block are installed in the front groove. The outer groove opening is sealed by a baffle to restrict and fix the position of the slider, the circumferential position adjustment block, and the axial position adjustment block inside.

3. The compressor blade cascade experimental apparatus with adjustable tandem blades at the leading edge according to claim 2, characterized in that: The slider is a long strip structure with evenly spaced holes; the circumferential position adjustment block is rectangular and located on the short side of the slider; the axial position adjustment block is strip-shaped and located on the long side of the slider. The number and size of the two types of adjustment blocks are designed according to actual needs.

4. A method for adjusting a compressor blade cascade experimental apparatus with adjustable tandem blades at the leading edge as described in any one of claims 1-3, characterized in that: When it is necessary to adjust the circumferential position of the leading edge leaflet, change the number of circumferential position adjustment blocks on both sides of the slider, or replace the circumferential position adjustment blocks of different sizes. When it is necessary to adjust the axial position of the leading edge leaflet, change the number of axial position adjustment blocks on both sides of the slider, or replace the axial position adjustment blocks of different sizes. When it is necessary to adjust the leading edge lobes intake angle, tighten the mounting angle of the leading edge lobes mounting block.

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