A design method for end-zone vortex generators suitable for lateral secondary flow control

Abstract

The present invention relates to a design method for end-zone vortex generators suitable for transverse secondary flow control, belonging to the technical field of compressor end-zone flow control. By arranging the vortex generators on the end wall of the channel between the leading and trailing edges of the blades, the concentrated vortex generated by the vortex generators directly acts on the transverse secondary flow in the blade end zone, effectively weakening the migration of the transverse secondary flow toward the suction surface of the blade, effectively controlling the diagonal separation phenomenon, and improving the aerodynamic performance of the blade. The provided design criteria and layout scheme provide a reference for the application of vortex generators in compressor blade channels.

Description

Technical Field

[0001] The invention relates to a design method of an end-region vortex generator suitable for transverse secondary flow regulation, and belongs to the technical field of compressor end-region flow control. Background Art

[0002] Vortex generators (VGs) are a simple, economical, and easy-to-implement passive flow control technology with high research value and broad application prospects in the field of flow control. As early as the late 1940s, VGs were widely used in aviation outflow control. Their primary function was to delay boundary layer separation, increase wing lift, and prevent aircraft from swaying and buffeting due to airflow separation.

[0003] Given the obvious advantages of vortex generators in the field of outflow flow control, researchers have begun to try to apply them to the suction surface of the compressor or the end wall of the leading edge of the blade since the 1960s. They mainly weaken the corner separation and improve the aerodynamic performance of the compressor through the following two mechanisms: one is to deflect the direction of the airflow; the other is to mix the high-energy fluid of the free stream with the low-energy fluid near the end wall through the concentrated vortex generated at the tip, thereby enhancing the ability of the boundary layer to resist the adverse pressure gradient. Summary of the Invention

[0004] The purpose of the present invention is to explore and broaden the effect and application scope of vortex generators in compressor blades, and creatively propose a design method for end-zone vortex generators suitable for lateral secondary flow regulation.

[0005] The innovations of this method include: by arranging the vortex generator on the end wall of the channel between the leading edge and the trailing edge of the blade, the concentrated vortex generated by the vortex generator directly acts on the lateral secondary flow in the blade end area, effectively weakening the migration of the lateral secondary flow to the suction surface of the blade, achieving effective control of the diagonal zone separation phenomenon, and improving the aerodynamic performance of the blade. The provided design criteria and layout scheme can provide a reference for the application of vortex generators in compressor blade channels.

[0006] Beneficial effects

[0007] The method proposed in this paper provides an effective reference for the design and application of end-zone vortex generators in compressor blade passages. The proposed aerodynamic layout schemes for single and dual vortex generators can effectively suppress the migration of lateral secondary flow toward the suction surface of the blade, thereby weakening the development of corner separation and effectively improving the performance of compressor blades. This lays the foundation for the engineering application of end-zone vortex generator technology in compressors. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic diagram of the geometric shape of a rectangular blade vortex generator;

[0009] Figure 2 This is a schematic diagram of the geometric shape of a compressor cascade;

[0010] Figure 3 This is a geometric diagram of the blade profile of a compressor cascade;

[0011] Figure 4 It is a single vortex generator aerodynamic layout scheme;

[0012] Figure 5 It is a dual vortex generator aerodynamic layout scheme. DETAILED DESCRIPTION

[0013] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0014] A method for designing an end-zone vortex generator suitable for transverse secondary flow regulation comprises the following steps:

[0015] Step 1: Determine the position of the rectangular blade vortex generator on the end wall of the front and rear ends of the compressor blade. The geometric shape of the rectangular blade vortex generator is as follows: Figure 1 shown.

[0016] Specifically, the flow field at the end of the compressor blade is analyzed, focusing on the endwall transverse secondary flow and the weak transverse secondary flow near the endwall. The intensity of the transverse secondary flow can be determined by comparing the endwall streamlines with the spanwise streamlines of the weak transverse secondary flow near the endwall. The greater the directional deviation between the endwall streamlines and the near-endwall streamlines, the stronger the transverse secondary flow in this area.

[0017] Determine the installation location of the end zone vortex generator according to the following design criteria:

[0018] For the single vortex generator design in the end zone, the vortex generator is more suitable to be arranged upstream of the starting position of the corner separation, close to the suction side of the cascade;

[0019] For the design of multiple vortex generators in the end area, the flow direction range of the concentrated vortex generated by the vortex generator should be maximized to prevent overlapping of the range of action. At the same time, attention should be paid to avoiding the concentrated vortices generated by each vortex generator from converging in the downstream of the blade channel to induce near-wall flow separation.

[0020] Step 2: Select appropriate values for angle of attack, length, width, and height based on the installation location of the rectangular blade vortex generator.

[0021] Step 3: Determine the optimal installation position, angle of attack, length, width, and height of the vortex generator to obtain the aerodynamic layout plan of the vortex generator.

[0022] The attack angle of the vortex generator is 15°-20°, and the attack angle of the vortex generator is the angle between the airflow direction at the top of the vortex generator and its length direction.

[0023] The length of the vortex generator is 5%-10% of the chord length of the compressor blade;

[0024] The height of the vortex generator is 10%-100% of the local boundary layer thickness;

[0025] The width of the eddy current generator is the minimum value that can be met by the processing technology and must meet the strength requirements.

[0026] Specifically, the reference design guidelines are as follows:

[0027] First, the larger the vortex generator's angle of attack, the stronger its suppression of the lateral secondary flow. When determining the vortex generator's angle of attack, it is necessary to avoid severe flow separation on the leeward side of the vortex generator.

[0028] Second, when designing a vortex generator, the flow control effect of the vortex generator and the additional losses it generates must be weighed to select the optimal length value.

[0029] The mechanism of action of the end zone vortex generator on the lateral secondary flow includes:

[0030] First, the vortex generators themselves directly block the lateral secondary flow. Second, the concentrated vortex generated at the top of the vortex generators weakens the lateral secondary flow in the end zone and simultaneously reduces the development of the channel vortex. Through these two mechanisms, the end zone vortex generators can significantly reduce the migration of lateral secondary flow toward the suction side, effectively reducing corner separation and significantly improving the aerodynamic performance of the compressor blades.

[0031] The rotation direction of the concentrated vortex generated at the top of the vortex generator is opposite to the movement direction of the end zone lateral secondary flow and the rotation direction of the channel vortex. This is the main reason why the concentrated vortex can weaken the development of the end zone lateral secondary flow and the channel vortex.

[0032] In addition, it is necessary to avoid the width and height of the vortex generator being too large, which will lead to additional losses generated by the vortex generator.

[0033] The aerodynamic layout design of vortex generators is a process of continuous optimization. The optimal aerodynamic layout scheme of vortex generators can be obtained by comparing a large number of schemes.

[0034] Example

[0035] By using the above method, the end zone vortex generator scheme of a compressor cascade is designed. The geometric shape of the cascade is as follows: Figure 2 As shown, its blade geometry and geometric parameters are as follows Figure 3 and as shown in Table 1.

[0036] After comparing a large number of schemes, the final aerodynamic layout schemes of single vortex generator and double vortex generator are as follows: Figure 4 and Figure 5 As shown in the figure, the installation position and geometric parameters of the vortex generator on the blade end wall in the two schemes are shown.

[0037] Numerical and experimental research results show that both vortex generator aerodynamic layout schemes can effectively delay the occurrence of corner separation and reduce the height of corner separation by weakening the lateral secondary flow in the side end area of the suction surface of the blade, thereby significantly improving the aerodynamic performance of the flat blade.

[0038] Table 1 Blade geometry parameters

[0039]

[0040] Numerical results show that the end-zone vortex generators work through two mechanisms:

[0041] First, the vortex generator itself has a direct blocking effect on the lateral secondary flow;

[0042] Second, the concentrated vortex generated at the top of the vortex generator can weaken the lateral secondary flow in the end area and weaken the development of the channel vortex.

[0043] It should be noted that the rotation direction of the concentrated vortex generated at the top of the vortex generator is opposite to the movement direction of the end zone lateral secondary flow and the rotation direction of the channel vortex. This is the main reason why the concentrated vortex can weaken the development of the end zone lateral secondary flow and the channel vortex.

Claims

1. A design method for an end zone vortex generator suitable for transverse secondary flow control, characterized in that: The following steps are involved: Step 1: Determine the position of the rectangular blade vortex generator on the end wall of the front and rear ends of the compressor blade and the inter-edge channel; The flow field at the end of the compressor blade was analyzed, focusing on the endwall lateral secondary flow and the weak lateral secondary flow near the endwall. The intensity of the lateral secondary flow was determined by comparing the endwall streamlines with the spanwise streamlines of the weak lateral secondary flow near the endwall. The greater the deviation in direction between the endwall streamlines and the near-endwall streamlines, the stronger the lateral secondary flow. Determine the installation location of the end zone vortex generator according to the following design criteria: For the single vortex generator design in the end zone, the vortex generator should be arranged upstream of the start position of the corner separation, close to the suction side of the cascade; For the design of multiple vortex generators in the end area, the flow direction range of the concentrated vortex generated by the vortex generator should be maximized to prevent overlap of the range of action. At the same time, attention should be paid to avoid the concentrated vortices generated by each vortex generator from intersecting in the downstream of the blade channel to induce near-wall flow separation. Step 2: Select the optimal angle of attack, length, width, and height based on the installation location of the rectangular blade vortex generator; Step 3: Determine the optimal installation position, angle of attack, length, width, and height of the vortex generator to obtain the aerodynamic layout plan of the vortex generator.

2. The method for designing an end-zone vortex generator suitable for transverse secondary flow control according to claim 1, characterized in that: The attack angle of the vortex generator is 15°-20°, and the attack angle of the vortex generator is the angle between the airflow direction at the top of the vortex generator and its length direction.

3. The method for designing an end-zone vortex generator suitable for lateral secondary flow control according to claim 1, characterized in that: The length of the vortex generator is 5%-10% of the chord length of the compressor blade.

4. The method for designing an end-zone vortex generator suitable for transverse secondary flow control according to claim 1, characterized in that: The height of the vortex generator is 10%-100% of the local boundary layer thickness.

5. The method for designing an end-zone vortex generator suitable for transverse secondary flow control according to claim 1, characterized in that: The width of the eddy current generator is the minimum value that can be satisfied by the processing technology and meets the strength requirements.

6. The method for designing an end-zone vortex generator suitable for transverse secondary flow control according to claim 1, characterized in that: Design criteria for end-zone vortex generators include: First, the larger the angle of attack of the vortex generator, the stronger the suppression effect on the lateral secondary flow; when determining the angle of attack of the vortex generator, it is necessary to avoid severe flow separation on the leeward side of the vortex generator; Second, when designing a vortex generator, the flow control effect of the vortex generator and the additional loss it generates must be weighed to select the optimal length value; The mechanism of action of the end zone vortex generator on the lateral secondary flow includes: The vortex generator itself has a direct blocking effect on the lateral secondary flow; The concentrated vortex generated at the top of the vortex generator can weaken the lateral secondary flow in the end area and weaken the development of the channel vortex; The rotation direction of the concentrated vortex generated at the top of the vortex generator is opposite to the movement direction of the transverse secondary flow in the end area and the rotation direction of the channel vortex.

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