An arrayed vortex generator regulation method suitable for fan end region flow

Abstract

The application discloses a kind of array vortex generator regulation methods suitable for fan end area flow, the regulation method includes the following steps: determining the array arrangement path of vortex generator on the passage end wall between fan blade leading edge to trailing edge;Determine the array arrangement range of vortex generator on the passage end wall between fan blade leading edge to trailing edge;According to the axial length of arrangement range, determine the axial spacing between upstream and downstream vortex generators in each arrangement path, and arrange the flow direction curved blade vortex generator along the arrangement path based on the arrangement range after interception;Determine the height of blade vortex generator, the width of root and tip, the first included angle between leading edge and root.The above-mentioned regulation method realizes the efficient regulation of end area transverse secondary flow in fan blade passage by vortex generator, significantly improves the aerodynamic performance of fan.

Description

Technical Field

[0001] This invention belongs to the field of flow control technology in the fan end region, specifically relating to a method for controlling an array-type eddy current generator suitable for flow in the fan end region. Background Technology

[0002] As loads increase, corner separation in fans becomes increasingly severe, posing a significant challenge to further improving fan performance. Within the fan blade passage, the circumferential pressure difference between the pressure and suction surfaces of adjacent blades drives low-energy fluid in the end region to migrate from the pressure surface to the suction surface, forming a transverse secondary flow. This transverse flow leads to a large accumulation of low-energy fluid in the suction-side corner region. When this fluid cannot resist the adverse pressure gradient, corner separation occurs. Therefore, transverse secondary flow in the end region is one of the key factors causing corner separation in fan blades, and controlling its flow is an effective way to mitigate corner separation at its source.

[0003] Various control techniques exist for addressing the problem of lateral secondary flow in the end region. Among them, vortex generators, with their simple structure, ease of implementation, ability to deflect airflow direction, and enhancement of boundary layer kinetic energy, hold promise as a highly efficient control method. Vortex generators were first proposed by Taylor in the late 1940s, initially used to delay boundary layer separation in airfoils to improve lift. After decades of development, this technology has been widely applied in aviation outflow control. Since the 1960s, researchers have begun to explore applying vortex generators to the suction surfaces and endwalls of fan / compressor blades to suppress secondary flow and reduce corner separation. However, their geometry and arrangement still require further innovation and optimization to fully realize their control effect on end-region flow. Summary of the Invention

[0004] This invention provides an array-type vortex generator control method suitable for flow in the end region of a fan. This control method enables the application of vortex generators in fans, and achieves efficient control of the transverse secondary flow in the end region of the fan blade channel through the vortex generator, significantly improving the aerodynamic performance of the fan.

[0005] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0006] This invention provides a method for controlling an array-type eddy current generator suitable for flow in the fan end region. The method includes the following steps:

[0007] Step 1: Determine the array arrangement path of the eddy current generator on the end wall of the channel between the leading edge and trailing edge of the fan blades;

[0008] Step 2: Determine the array arrangement range of the eddy current generator on the end wall of the channel between the leading edge and trailing edge of the fan blades;

[0009] Step 3: Based on the axial length of the arrangement range, determine the axial spacing between the upstream and downstream vortex generators in each arrangement path, and arrange the blade-type vortex generators with curved flow direction along the arrangement path after the arrangement range is cut off.

[0010] Step 4: Determine the height of the blade-type vortex generator, the width of the root and tip, and the first included angle between the leading edge and the root.

[0011] Furthermore, it also includes:

[0012] Step 5: Optimize and adjust the arrangement range, height, width, first included angle, axial spacing, and second included angle with the mainstream direction of the blade-type vortex generator based on the flow control effect.

[0013] Furthermore, in step 1, the specific process of determining the array-style layout path is as follows:

[0014] Extract the profiles of the suction and pressure surfaces at the root section of the fan blade. Using the axial position of the blade leading edge as the starting position, select the circumferential spacing according to the grid length, and copy and translate multiple profiles along the inner side of the channel as reference paths for the array arrangement of eddy current generators.

[0015] Furthermore, when determining the end position of each arrangement path, while ensuring that the transverse secondary flow in the end region does not act on the suction surface of adjacent blades, the axial range of each arrangement path should be minimized as much as possible. The flow control effect of the vortex generators can be balanced with the additional losses they generate by reducing the number of vortex generators.

[0016] Furthermore, in step 2, the array arrangement range starts at the axial position where the endwall flow begins to deviate from the mainstream direction, and ends at the endwall limit streamline from the pressure surface at the blade root to the trailing edge of the adjacent blade.

[0017] Furthermore, when optimizing the second included angle, the vortex generator located near the starting position of the transverse secondary flow in the end region is deflected toward the pressure surface, increasing its second included angle with the mainstream direction, thereby enhancing its ability to deflect low-energy fluid in the end region, while avoiding severe flow separation on the leeward side of the vortex generator.

[0018] Furthermore, under the premise of ensuring that the transverse secondary flow in the end region does not pass through the axial distance between the upstream and downstream vortex generators in each arrangement path and that the transverse secondary flow in the end region does not act on the suction surface, the axial distance between the upstream and downstream vortex generators should be increased as much as possible, and the additional losses caused by the vortex generators should be reduced by decreasing the axial length of the vortex generators.

[0019] Furthermore, the height of the blade-type vortex generator is less than the thickness of the transverse secondary flow in the end region;

[0020] The first included angle is greater than 0° and does not exceed 90°.

[0021] Furthermore, the width of the tip of the eddy current generator is less than or equal to the width of the root, with the width taken as the minimum value while ensuring structural strength.

[0022] In addition, the present invention also provides a fan in which blade-type vortex generators are arrayed on the end wall of the channel between the leading edge and trailing edge of the fan blades, and the blade-type vortex generators are arranged using the above-mentioned control method.

[0023] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0024] The array-type vortex generator control method of this invention realizes the layout of array-type vortex generators in the fan end region. By rationally distributing the position and number of blade-type vortex generators, the blade-type vortex generators are arranged in an array on the end wall between the leading and trailing edges of the fan blades. The direct blocking effect of the blade-type vortex generators and the concentrated vortices they induce effectively weaken the transverse secondary flow in the end region. This effectively suppresses the migration of low-energy fluid from the pressure surface to the suction surface of adjacent blades in the end region of the fan blade passage, significantly improving the flow characteristics in the end region and thus greatly increasing the operating margin of the fan. The array-type vortex generator control method of this invention not only optimizes the aerodynamic performance of the end region, but also provides important technical guidance and design reference for improving fan performance, and provides theoretical basis and practical reference for the optimized design of fans. It is of great significance for the efficient and reliable operation of modern aero engines. Attached Figure Description

[0025] Figure 1 This is a flowchart of the array-type eddy current generator control method of the present invention;

[0026] Figure 2 This is a schematic diagram of the reference path for the array arrangement of eddy current generators;

[0027] Figure 3 This is a schematic diagram of the array arrangement of eddy current generators;

[0028] Figure 4 This is a schematic diagram of a blade-type vortex generator with a curved flow direction;

[0029] Figure 5 It has a two-stage fan geometry;

[0030] Figure 6 It is a hub array eddy current generator arrangement scheme;

[0031] Figure 7 It is a casing array eddy current generator arrangement scheme;

[0032] Figure 8 This is the pressure ratio characteristic curve of the final stage fan;

[0033] Figure 9 This is the efficiency characteristic curve of the final stage fan.

[0034] Figure label:

[0035] 1-Suction surface root section profile, 2-Pressure surface root section profile, 3-Reference path, 4-Main flow line, 5-Arrangement range, 6-Starting position, 7-Ending position, 8-End wall transverse secondary flow line, 9-Arrangement path, 10-Guide vane, 11-First-stage moving vane, 12-First-stage stationary vane, 13-Second-stage moving vane, 14-Second-stage stationary vane, 15-Hub, 16-Suction surface, 17-Vortex generator, 18-Casing, w1-Tip width, w2-Root width, h-Height, l1-Tip axial length, l2-Root axial length, s-Circumferential spacing, θ-First included angle, z-Axial spacing. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] This invention innovatively distributes the blade-type vortex generator 17 array in the end region of the fan, and achieves efficient control of the transverse secondary flow in the end region of the fan blade channel through the blade-type vortex generator 17, which significantly improves the aerodynamic performance of the fan and provides a brand-new control idea for the design of modern high-performance fans.

[0038] Example 1

[0039] This embodiment provides a method for controlling an array-type eddy current generator suitable for flow in the fan end region, such as... Figure 1 As shown, the regulation method includes the following steps:

[0040] Step 1: Determine the array arrangement path 9 of the eddy current generator 17 on the end wall of the channel between the leading and trailing edges of the fan blades. Specifically, as shown... Figure 2 As shown, the suction surface root section profile 1 and pressure surface root section profile 2 of the fan blade are extracted, with the axial position of the blade leading edge point as the starting position. A suitable circumferential spacing s is selected based on the grid pitch length, and multiple profiles are copied and translated along the inner side of the channel, serving as the reference path 3 for the array arrangement of the eddy current generator.

[0041] Step 2, determine the array arrangement range 5 of the eddy current generator 17 on the end wall of the channel between the leading edge and trailing edge of the fan blades. Specifically, as shown... Figure 3 As shown, the flow field at the end region of the fan blades is analyzed, focusing on the lateral secondary flow and the main flow at the endwall. Figure 3 The diagram illustrates the transverse secondary flow streamline 8 and the main flow streamline 4 on the endwall. The axial position where the endwall flow begins to deviate from the main flow direction is taken as the starting position 6 of the array arrangement of the vortex generators 17, and the endwall limiting streamline from the pressure surface at the blade root to the trailing edge of the adjacent blade is taken as the ending position 7 of the array arrangement. Based on the above reference paths, the specific arrangement range 5 of the vortex generators 17 is determined.

[0042] Step 3: Based on the axial length of the arrangement range 5, determine the axial spacing z between the upstream and downstream vortex generators 17 on the same path, and arrange the flow-direction curved blade-type vortex generators 17 along the arrangement path 9 cut from the arrangement range 5. The blade-type vortex generators 17 designed based on the path are as follows: Figure 4 As shown.

[0043] Step 4: Select the height h, root width w2, tip width w1, and the first angle θ between the leading edge and root of the blade-type vortex generator 17. The height h of the blade-type vortex generator 17 is less than the thickness of the transverse secondary flow in the end region; the tip width w1 of the blade-type vortex generator 17 is less than or equal to the root width w2, and the width is the minimum value under the premise of ensuring structural strength; the first angle θ between the leading edge and root of the blade-type vortex generator 17 is 0°-90°. Figure 4 As shown, the parameters of the blade-type vortex generator 17 also include the tip axial length l1 and the root axial length l2.

[0044] Step 5: Optimize and adjust its height h, width, first included angle θ between the leading edge and the root, arrangement range 5, second included angle with the mainstream direction and axial spacing z according to the flow control effect, until the optimal layout scheme of the array eddy current generator 17 is determined.

[0045] Based on the above embodiments, when determining the end position of each arrangement path 9, under the premise of ensuring that the transverse secondary flow in the end region does not act on the suction surface 16 of the adjacent blade, the axial range of each path is minimized as much as possible, thereby reducing the number of vortex generators 17 and balancing their flow control effect with the additional losses they generate.

[0046] When optimizing the second angle between the vortex generator 17 and the mainstream direction, the vortex generator 17 located near the starting position of the transverse secondary flow in the end region is appropriately deflected toward the pressure surface to increase its angle with the mainstream direction, thereby enhancing its ability to deflect the low-energy fluid in the end region and avoiding severe flow separation on the leeward side of the vortex generator 17. Under the premise of ensuring that the transverse secondary flow in the end region does not pass through the axial spacing z between the upstream and downstream vortex generators 17 of each path and act on the suction surface 16, the axial spacing z between the upstream and downstream vortex generators 17 is increased as much as possible. The additional losses caused by the axial length of the vortex generator 17 are reduced by decreasing the axial length of the vortex generator 17, and the axial spacing z between each row of vortex generators 17 can be inconsistent.

[0047] The optimal aerodynamic layout of the array-type vortex generator 17 can be determined through comparison and analysis of a large amount of data.

[0048] The array-type vortex generator control method described above achieves the layout of the array-type vortex generator in the fan end region. By rationally distributing the position and number of blade-type vortex generators 17, the blade-type vortex generators 17 are arranged in an array on the end wall between the leading and trailing edges of the fan blades. The direct blocking effect of the blade-type vortex generators 17 and the concentrated vortices they induce effectively weaken the transverse secondary flow in the end region. This effectively suppresses the migration of low-energy fluid from the pressure surface to the suction surface 16 of adjacent blades in the end region of the fan blade passage, significantly improving the flow characteristics in the end region and thus greatly increasing the operating margin of the fan. The array-type vortex generator control method of this invention not only optimizes the aerodynamic performance of the end region but also provides important technical guidance and design reference for improving fan performance, and provides theoretical basis and practical reference for the optimized design of fans. It is of great significance for the efficient and reliable operation of modern aero engines.

[0049] Example 2

[0050] Taking a two-stage fan as the research object, based on the control method in the above embodiments, an array-type vortex generator scheme is designed on the hub 15 and casing 18 in the last-stage stator blade channel where the transverse secondary flow is strong in the end region. The geometric shape of the two-stage fan is as follows: Figure 5 As shown, it includes guide vane 10, primary moving vane 11, primary stationary vane 12, secondary moving vane 13, and secondary stationary vane 14.

[0051] Through continuous optimization and adjustment, the arrangement schemes of the arrayed eddy current generators 17 on the hub 15 and the casing 18 are as follows: Figure 6 and Figure 7As shown in the figure, the eddy current generators 17 arranged on the hub 15 have a height h of 1 mm and a width of 0.3 mm, a circumferential spacing s between the eddy current generators 17 is 3.75 mm, and an axial spacing z between the eddy current generators 17 is 4 mm; the eddy current generators 17 arranged on the casing 18 have a height h of 1.5 mm and a width of 0.3 mm, a circumferential spacing s between the eddy current generators 17 is 5.41 mm, and an axial spacing z between the eddy current generators 17 is 4.15 mm. Furthermore, the axial spacing z and circumferential spacing s of the arrayed eddy current generators on the hub 15 and casing 18 are also indicated in the figure.

[0052] Numerical simulation results show that the arrayed vortex generators 17 on the hub 15 and casing 18 can effectively suppress the transverse secondary flow in the end region through direct blocking and induced concentrated vortices, significantly improving the end region flow. This increases the overall margin by 2.2% without significantly affecting the pressure ratio and efficiency of the final-stage fan. The pressure ratio and efficiency characteristics of the final-stage fan before and after adjustment are as follows: Figure 8 and Figure 9 As shown.

[0053] Example 3

[0054] This embodiment provides a fan in which blade-type vortex generators 17 are arrayed on the end wall of the channel between the leading edge and trailing edge of the fan blades. The blade-type vortex generators 17 are arranged using the control method described in Embodiment 1 above.

[0055] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A method for controlling an array-type eddy current generator suitable for flow in the fan end region, characterized in that, Includes the following steps: Step 1: Determine the array arrangement path of the eddy current generator on the end wall of the channel between the leading edge and trailing edge of the fan blade: Extract the profiles of the suction and pressure surfaces of the fan blade root section, take the axial position of the blade leading edge point as the starting position, select the circumferential spacing according to the grid length, and copy and translate multiple profiles along the inner side of the channel as reference paths for the array arrangement of the eddy current generator. Step 2: Determine the array arrangement range of the vortex generators on the endwall of the channel between the leading and trailing edges of the fan blades. The array arrangement range starts at the axial position where the endwall flow begins to deviate from the mainstream direction, and ends at the endwall limit streamline from the pressure surface at the blade root to the trailing edge of the adjacent blade. When determining the end position of each arrangement path, on the premise of ensuring that the transverse secondary flow in the end region does not act on the suction surface of the adjacent blade, the axial range of each arrangement path should be minimized as much as possible. The flow control effect and the additional losses generated by the vortex generators are balanced by reducing the number of vortex generators. Step 3: Based on the axial length of the arrangement range, determine the axial spacing between the upstream and downstream vortex generators in each arrangement path, and arrange the blade-type vortex generators with curved flow direction along the arrangement path after the arrangement range is cut off. Step 4: Determine the height of the blade-type vortex generator, the width of the root and tip, and the first included angle between the leading edge and the root; the height of the vortex generator is less than the thickness of the transverse secondary flow in the end region; the width of the tip of the blade-type vortex generator is less than or equal to the width of the root, and the width is taken as the minimum value under the premise of ensuring structural strength; the value of the first included angle is greater than 0° and does not exceed 90°. Step 5: Optimize and adjust the arrangement range, height, width, first included angle, axial spacing, and second included angle with the mainstream direction of the blade-type vortex generator based on the flow control effect.

2. The control method as described in claim 1, characterized in that, When optimizing the second included angle, the vortex generator located near the starting position of the transverse secondary flow in the end region is deflected toward the pressure surface, increasing its second included angle with the mainstream direction, thereby enhancing its ability to deflect low-energy fluid in the end region, while avoiding severe flow separation on the leeward side of the vortex generator.

3. The control method according to any one of claims 1-2, characterized in that, Under the premise of ensuring that the transverse secondary flow in the end region does not pass through the axial distance between the upstream and downstream vortex generators in each arrangement path and that the transverse secondary flow in the end region does not act on the suction surface, the axial distance between the upstream and downstream vortex generators should be increased as much as possible, and the additional losses caused by the axial length of the vortex generators should be reduced.

4. A fan, characterized in that, The fan has blade-type vortex generators arranged in an array on the end wall of the channel between the leading edge and trailing edge of the fan blades. The blade-type vortex generators are arranged using the control method described in any one of claims 1-3.

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