High-load supersonic cascade and gas compressor

Abstract

The invention provides a high-load supersonic cascade and a gas compressor, and belongs to the technical field of gas turbine gas compressors. The blade grid comprises blades and vortex generators, the vortex generators are installed in the front edge areas of the blades, and the vortex generators and the suction surfaces of the blades are located on the surfaces of the same sides of the blades. In the airflow direction corresponding to the blades, the height of the vortex generator is gradually reduced, the width of the vortex generator is gradually increased, and the width of the vortex generator is the size of the vortex generator in the spreading direction of the blades. The vortex generators in specific shapes are arranged on the surfaces of the blades, so that after airflow passes through the vortex generators, two reverse vortex pairs spaced by a certain distance can be generated, and the two reverse vortex pairs can entrain the airflow from a mainstream area with more gas and supplement the airflow to a shock wave / boundary layer interference separation area lacking gas; therefore, flow separation of the rear half section of the suction surface is inhibited, flow loss is reduced, and aerodynamic performance of the cascade is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas turbine compressors, and in particular relates to a high-load supersonic blade grid and a compressor. Background Art

[0002] As the core component of an aircraft engine, the axial-flow compressor plays a significant role in the engine's performance and operational stability. As performance demands increase, the compressor speed also increases. Excessively high speeds cause the relative incoming flow at the rotor channel inlet to become supersonic. Shock waves are generated at the leading edge of the blades. When the shock waves hit the suction surface of the blades, shock wave / boundary layer interference occurs within the blade channel. This induces complex flow within the rotor channel, accompanied by significant flow losses. As the operating flow rate decreases, this ultimately causes compressor instability. Currently, mainstream research on compressor channel shock wave / boundary layer interference is primarily based on control methods under conventional subsonic conditions, which are less targeted and have a limited range of applicable operating conditions. Summary of the Invention

[0003] The purpose of this application is to provide a high-load supersonic blade grid and compressor to solve the above-mentioned technical problems existing in the prior art.

[0004] This application is implemented as follows: In the first aspect, an embodiment of the present application provides a high-load supersonic blade, comprising a blade and a vortex generator, wherein the vortex generator is installed in the leading edge area of ​​the blade, and the vortex generator and the suction surface of the blade are located on the same side surface of the blade; along the airflow direction corresponding to the blade, the height of the vortex generator gradually decreases and the width of the vortex generator gradually increases, and the width of the vortex generator is the size of the vortex generator in the span direction of the blade.

[0005] In a second aspect, an embodiment of the present application provides a compressor comprising the high-load supersonic blade grid provided in the embodiment of the first aspect.

[0006] The technical solution adopted by the present invention can achieve the following beneficial effects: In the present application, a vortex generator is provided on the surface of the blade and the shape of the vortex generator is restricted so that after the airflow passes through the vortex generator, two reverse vortex pairs separated by a certain distance can be generated. The two reverse vortex pairs can suck the airflow from the mainstream area with more gas and replenish it to the shock wave / boundary layer interference separation area where there is a lack of gas, and exchange momentum with the shock wave / boundary layer interference separation area, thereby suppressing the flow separation in the rear half of the suction surface, suppressing the boundary layer separation of the suction surface, reducing flow losses, improving the aerodynamic performance of the blade, widening the near-stall flow, and delaying the time of compressor instability. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0008] Figure 1 is a schematic diagram of the overall structure of the cascade provided in some embodiments of the present application; Figure 2 This is a schematic diagram of the cooperation between the blades and the vortex generator provided in some embodiments of the present application Figure 1 ; Figure 3 This is a schematic diagram of the cooperation between the blades and the vortex generator provided in some embodiments of the present application Figure 2 ; Figure 4 This is a schematic diagram of the cooperation between the blades and the vortex generator provided in some embodiments of the present application Figure 3 ; Figure 5 This is a schematic diagram of the gas flow on the blade surface provided by some embodiments of the present application. Figure 1 ; Figure 6 This is a schematic diagram of the gas flow on the blade surface corresponding to the prototype blade grid Figure 1 ; Figure 7 This is a schematic diagram of the gas flow on the blade surface provided by some embodiments of the present application. Figure 2 ; Figure 8 This is a schematic diagram of the gas flow on the blade surface corresponding to the prototype blade grid Figure 2 ; Figure 9 This is a schematic diagram of the gas flow on the blade surface provided by some embodiments of the present application. Figure 3 ; Figure 10 Some embodiments of the present application provide a comparison of the characteristic lines of the cascade with the prototype cascade. Figure 1 ; Figure 11 Some embodiments of the present application provide a comparison of the characteristic lines of the cascade with the prototype cascade. Figure 2 ; Figure 12 It is a Mach number cloud diagram of the middle section of the blade channel of the blade cascade provided in some embodiments of the present application and the prototype blade cascade.

[0009] In the figure: 10 - cascade, 100 - blade, 110 - suction surface, 200 - vortex generator, 300 - mainstream area, 400 - SWBLI separation area. DETAILED DESCRIPTION

[0010] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0011] An embodiment of the present application provides a high-load supersonic blade cascade, in which a vortex generator 200 is provided on the surface of the blade 100 , and the vortex generator 200 is used to suppress flow separation on the surface of the blade 100 , thereby avoiding instability of the compressor.

[0012] The structure of the cascade 10 provided in the embodiment of the present application can be referred to Figure 1 As shown, the cascade 10 includes a blade 100 and a vortex generator 200. Figure 1 In order to clearly show the overall structure of the cascade 10, the vortex generator 200 is not drawn. Figures 2 to 4 As shown, the vortex generator 200 is installed in the leading edge region of the blade 100 , and the vortex generator 200 and the suction surface 110 of the blade 100 are located on the same side surface of the blade 100 .

[0013] When the blade 100 is working, the airflow flows through the surface of the blade 100. The leading edge is the part of the blade 100 that the airflow first contacts, and the airflow flows into the blade 100 channel from the leading edge of the blade 100. The trailing edge is where the airflow flows out of the blade 100, and the airflow flows out of the blade 100 channel at the trailing edge and enters the downstream. The leading edge area represents a part of the front end of the blade 100, and the vortex generator 200 can be located within the range corresponding to the leading edge area. It can be understood that the area behind the blade 100 in the incoming flow direction does not belong to the leading edge area, but to the trailing edge area. Figure 2 and Figure 3 In the figure, the incoming flow direction is indicated by a dotted arrow.

[0014] The blade 100 is a thin sheet structure, with the convex surface of the blade 100 being the suction surface 110 and the concave surface being the pressure surface. The vortex generator 200 is located on the same side of the blade 100 as the suction surface 110 and can adjust the flow state of the suction surface 110.

[0015] In the embodiment provided in the present application, along the airflow direction corresponding to the blade 100 , the height of the vortex generator 200 gradually decreases and the width of the vortex generator 200 gradually increases. The width of the vortex generator 200 is the size of the vortex generator 200 in the span direction of the blade 100 .

[0016] The vortex generators 200 are mounted on the surface of the blade 100. They are arranged to protrude relative to the surface of the blade 100. The height of the vortex generators 200 refers to the distance between any part of the vortex generators 200 and the surface of the blade 100, and also refers to the extent to which the vortex generators 200 protrude relative to the surface of the blade 100. The spanwise direction of the blade 100 refers to the direction from the root to the tip of the blade 100.

[0017] Similar to blade 100, air flows over the surface of vortex generators 200. The leading edge of the vortex generator 200 is where it first contacts the airflow, while the trailing edge is where the airflow exits the vortex generator 200. The height of the vortex generator 200 gradually decreases along the direction of airflow over the surface of blade 100, while the width of the vortex generator 200 gradually increases along the direction of airflow over the surface of blade 100, forming an inverted wedge-shaped structure with a high leading edge and a low trailing edge, and a narrow leading edge and a wide trailing edge.

[0018] In the prior art, the blade 100 surface is not provided with a vortex generator 200. During the operation of the compressor, as the working conditions change, the working flow gradually decreases, which will increase the downstream pressure of the blade 100. The airflow cannot flow normally on the surface of the blade 100. The shock wave / boundary layer interference will produce a separation zone near the suction surface 110. The suction surface 110 of the blade 100 will separate, and with obvious flow loss, it will cause the compressor to become unstable. Figure 8 As shown. Boundary layer is an important concept in fluid mechanics. It refers to a thin layer of fluid close to the surface of an object when the fluid flows around it.

[0019] In the embodiment of the present application, a vortex generator 200 is provided on the surface of the blade 100. When the airflow passes through the vortex generator 200 after the shock wave deceleration, the airflow circulates. Figure 9 As shown. Part of the airflow flows through the two sides of the vortex generator 200 under the obstruction of the leading edge of the vortex generator 200, flowing through the side walls of the vortex generator 200 and the surface of the blade 100, and part of the airflow flows through the upper surface of the vortex generator 200. For details, please refer to Figure 4 As shown, the flow path of the air flow is represented by the dotted arrows.

[0020] After passing the leading edge, the airflow flows through both sides of the vortex generator 200. The airflow hits the leading edge and stagnates, forming a high-pressure air source. The airflow flowing through the upper surface of the vortex generator 200 forms a leeward side relative to the leading edge. The flow on the leeward side separates and forms a low-pressure air source. The airflow on the upper surface of the vortex generator 200 has a different pressure than the airflow on both sides. Driven by the pressure difference, two vortices with opposite rotation directions are generated at the edge of the vortex generator 200. These vortex pairs are referred to as counter-rotating vortex pairs. The vortex pairs develop parallel to the suction surface 110. Figure 5 As shown, Figure 5The diagram shows the distribution of vortex pairs on the surface of the blade 100. At the same time, since the two sides of the vortex generator 200 are high pressure and the upper surface is low pressure, the direction of the vortex is from high pressure to low pressure, and the two vortex pairs are inward-facing opposite vortices. Figure 4 The direction is indicated by the solid arrow.

[0021] Under the action of the reverse vortex pair, the airflow can be entrained from the mainstream area 300 with more gas and replenished to the shock wave / boundary layer interference (SWBLI) separation area with less gas, thereby suppressing the flow separation in the rear half of the suction surface 110. Figure 7 As shown, Figure 7 The main flow region 300 is located above the SWBLI separation region 400. Figure 6 The corresponding blade 100 is not provided with a vortex generator 200. Figure 6 There is no gas exchange between the mainstream region 300 and the SWBLI separation region 400, and the boundary layer separation on the suction surface 110 cannot be suppressed. Figure 6 and Figure 7 , the X-axis represents the span direction of the blade 100 , and the Y-axis represents the circumferential direction of the blade 100 .

[0022] Under the same operating conditions, even if the operating flow rate decreases, the opposing vortex pairs can replenish gas from the mainstream region 300 to the gas-deficient shock wave / boundary layer interference (SWBLI) separation zone, thereby suppressing flow separation in the rear half of the suction surface 110. Boundary layer separation on the suction surface 110 will only occur if the operating flow rate continues to decrease, until the opposing vortex pairs are unable to entrain any more gas to replenish the shock wave / boundary layer interference (SWBLI) separation zone, thereby delaying the onset of compressor instability. In actual operation, the compressor flow rate will not decrease to the point where the vortex generators 200 become ineffective. Therefore, the installation of vortex generators 200 can ensure stable compressor operation.

[0023] The vortex generator 200 delays the time point when the boundary layer separation of the suction surface 110 occurs, so that the cascade 10 structure can be applied to low working flow, broadens its corresponding working flow range, and also broadens its near-stall flow.

[0024] The blade cascade 10 provided in the embodiment of the present application is mainly designed and studied for supersonic conditions and can control the compressor under supersonic conditions.

[0025] refer to Figure 10 and Figure 11 As shown, Figure 10 and Figure 11Figure 2 shows a comparison of the characteristic lines of the prototype cascade 10 and the cascade 10 provided in the embodiment of the present application under the same operating conditions. The prototype cascade 10 represents the cascade 10 structure without the vortex generators 200. Under the flow control of the vortex generators 200, the cascade 10 provided in the embodiment of the present application has an improved static pressure ratio and a wider range of incoming airflow angles.

[0026] For the isotangential velocity characteristics of the transonic rotor blade cascade 10, as the operating conditions weaken (i.e., the incoming flow velocity decreases), the incoming flow angle decreases. Under low incoming flow conditions, due to the reduction of gas entering the blade cascade 10, under the combined effect of stronger shock waves and higher back pressure, the SWBLI separation in the blade cascade 10 channel is enhanced, and the greater separation leads to a decrease in the boosting capacity of the blade cascade 10. Under near-stall conditions, the flow separation is in a state of extreme stability. If the blade cascade 10 is further deepened, it will enter an unstable operating condition. The working effect of the present invention can suppress separation and thus improve the boosting capacity of the blade cascade 10. The smaller separation area delays the near-stall operating condition. Therefore, the near-stall operating condition of the controlled blade cascade 10 has a smaller incoming flow angle, and the range of the incoming flow angle is widened. The widened near-stall side incoming flow angle indicates that the blade cascade 10 has a larger stable operating range.

[0027] Figure 12 The middle is a Mach number cloud diagram of the middle section of the cascade passage of the cascade 10 provided by the present application and the prototype cascade. Figure 12 The prototype blade is shown above, and the controlled blade 10 of the present invention is shown below. By comparing the two blades under different working conditions, combined with Figure 10 and Figure 11 It can be seen that the separation area of ​​the suction surface 110 of the controlled cascade 10 is suppressed, thereby widening the working range.

[0028] The leading edge height of the vortex generator 200 is defined as a first height. During the operation of the cascade 10, the shock wave generated interferes with the boundary layer on the surface of the blade 100. The boundary layer thickness corresponding to the location of interference is the first thickness. The first height is between 75% and 85% of the first thickness, preferably 80%. The leading edge height of the vortex generator 200 is generally between 75% and 85% of the boundary layer thickness at the designated location, and both are of the same order of magnitude. This ensures that the vortex generator 200 can successfully entrain gas from the mainstream region 300 to the SWBLI separation region 400, suppressing boundary layer separation on the suction surface 110. The operation of the cascade 10 refers to the operation state under near-stall conditions.

[0029] In some embodiments, reference Figure 2 As shown, the vortex generator 200 includes two side walls connecting its leading edge and trailing edge. The angle between the two side walls is between 30 degrees and 35 degrees, which limits the generation spacing of the opposing vortex pairs to ensure that the mainstream gas can be smoothly entrained, thereby suppressing the boundary layer separation of the suction surface 110. Figure 2In the figure, the angle between the two side walls is marked with a.

[0030] In some embodiments, the two side walls connecting the leading edge and the trailing edge of the vortex generator 200 intersect, and the two side walls directly intersect to form an angle. The width of the leading edge of the vortex generator 200 is zero. Figure 2 shown.

[0031] In other embodiments, the two side walls connecting the leading edge and the trailing edge of the vortex generator 200 are connected via a connecting surface, and the two side walls are not directly connected.

[0032] refer to Figure 3 As shown, in some embodiments of the present application, there are multiple vortex generators 200. The multiple vortex generators 200 are arranged along the span direction of the blade 100, with intervals between adjacent vortex generators 200. The provision of multiple vortex generators 200 increases the coverage area of ​​the corresponding opposing vortex pairs formed, further suppressing boundary layer separation on the suction surface 110.

[0033] In some preferred embodiments, in the spanwise direction of the blade 100, the spacing between the trailing edges of two adjacent vortex generators 200 is a first distance, the width of the trailing edge of the vortex generator 200 is the first width, and the ratio of the first distance to the first width is between 2.3 and 2.7. The spacing between two adjacent vortex generators 200 decreases as their widths increase. Therefore, in this embodiment, the first distance represents the spacing between the trailing edges of two adjacent vortex generators 200, and the first width represents the width of the trailing edge of the vortex generator 200. Further preferably, the first distance is 2.5 times the first width. This prevents the vortex pairs generated by two adjacent vortex generators 200 from influencing each other.

[0034] The height of the trailing edge of the vortex generator 200 is lower than the leading edge. In some embodiments, the height of the trailing edge of the vortex generator 200 is less than one-tenth of the height of the leading edge of the vortex generator 200. The height of the trailing edge cannot be too high, as this will result in the low-pressure gas source being insufficiently low-pressure, thus affecting the entrainment effect of the vortex pairs. Generally, the height of the trailing edge of the vortex generator 200 is at most one-tenth of the height of the leading edge of the vortex generator 200, and the height of the trailing edge of the vortex generator 200 can also be zero.

[0035] When installing the vortex generator 200, the distance between the trailing edge of the vortex generator 200 and the leading edge of the blade 100 is between 8% and 12% of the chord length of the blade 100, determining the installation position of the vortex generator 200. The leading edge of the blade 100 has a relatively large area. To ensure that the vortices generated by the vortex generator 200 can effectively suppress boundary layer separation on the suction surface 110, the vortex generator 200 must be located within the SWBLI separation zone 400 or the leading edge of the blade 100. The trailing edge of the vortex generator 200 is typically located between 8% and 12% of the axial chord length of the blade 100. In practice, the position of 10% of the axial chord length can be selected.

[0036] In some embodiments, the trailing edge of the vortex generator 200 is parallel to the spanwise direction of the blade 100. When the trailing edge height of the vortex generator 200 is zero, the trailing edge of the vortex generator 200 is an edge structure. When the trailing edge height of the vortex generator 200 is not zero, the trailing edge of the vortex generator 200 is a surface structure. Either the edge structure or the surface structure can be parallel to the spanwise direction of the blade 100 to ensure that the opposing vortex pairs generated by the vortex generator 200 are parallel to the incoming flow direction, thereby preventing interference between the vortex pairs and the main flow in the spanwise direction.

[0037] An embodiment of the present application further provides a compressor, which includes the high-load supersonic blade cascade 10 provided in any of the above embodiments.

[0038] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0039] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be covered by the scope of protection of the present invention.

Claims

1. A high-load supersonic blade cascade, characterized in that: The invention comprises a blade (100) and a vortex generator (200), wherein the vortex generator (200) is installed in the leading edge region of the blade (100), and the vortex generator (200) and the suction surface (110) of the blade (100) are located on the same side surface of the blade (100); Along the airflow direction corresponding to the blade (100), the height of the vortex generator (200) gradually decreases, and the width of the vortex generator (200) gradually increases. The width of the vortex generator (200) is the size of the vortex generator (200) in the span direction of the blade (100).

2. The high-load supersonic blade cascade according to claim 1, characterized in that: The height of the leading edge of the vortex generator (200) is a first height, the shock wave generated during the operation of the cascade (10) interferes with the boundary layer on the surface of the blade (100), the boundary layer thickness corresponding to the interference position is a first thickness, and the first height is between 75% and 85% of the first thickness.

3. The high-load supersonic blade cascade according to claim 1, characterized in that: The vortex generator (200) comprises two side walls connecting a leading edge and a trailing edge thereof, and the angle between the two side walls is between 30 degrees and 35 degrees.

4. The high-load supersonic blade cascade according to claim 1, characterized in that: There are a plurality of vortex generators (200), and the plurality of vortex generators (200) are arranged along the span direction of the blade (100), with two adjacent vortex generators (200) being arranged at intervals.

5. The high-load supersonic blade cascade according to claim 4, characterized in that: In the span direction of the blade (100), the spacing between the trailing edges of two adjacent vortex generators (200) is a first distance, the width of the trailing edge of the vortex generator (200) is a first width, and the ratio of the first distance to the first width is between 2.3 and 2.

7.

6. The high-load supersonic blade cascade according to claim 1, characterized in that: The height of the trailing edge of the vortex generator (200) is less than one tenth of the height of the leading edge of the vortex generator (200).

7. The high-load supersonic blade cascade according to claim 1, characterized in that: The vortex generator (200) comprises two side walls connecting the leading edge and the trailing edge thereof, and the two side walls intersect or are connected via a connecting surface.

8. The high-load supersonic blade cascade according to claim 1, characterized in that: The distance between the trailing edge of the vortex generator (200) and the leading edge of the blade (100) is between 8% and 12% of the chord length of the blade (100).

9. The high-load supersonic blade cascade according to claim 1, characterized in that: The trailing edge of the vortex generator (200) is parallel to the span direction of the blade (100).

10. A compressor, characterized in that: Comprising the high-load supersonic blade cascade (10) according to any one of claims 1 to 9.

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