A method for designing an inner hub vortex generator of a stationary blade of an axial flow compressor

Abstract

The application relates to a design method of an axial flow compressor static blade inner hub vortex generator, and belongs to the technical field of fluid mechanics flow control. First, the installation position of the vortex generator on the hub is selected, and the axial position and the circumferential position of the vortex generator are determined. Then, the geometric parameters of the vortex generator are selected, including the height and the windward area of the vortex generator, and the length and the attack angle of the vortex generator are determined. Finally, the length of the vortex generator is determined according to the selected windward area and height of the vortex generator. Compared with the prior art, the vortex generator scheme does not need to be optimized by relying on a global optimization method, and a large amount of calculation time and calculation resources are saved.

Description

Technical Field

[0001] This invention relates to a design method for a vortex generator on the inner hub of the stator blade of an axial compressor, belonging to the field of fluid dynamics flow control technology. Background Technology

[0002] For a long time, reducing weight and improving efficiency have been cutting-edge and challenging issues in the field of modern aero-engines, attracting widespread and continuous attention. Developing high-load axial-flow compressors, which can meet the compressed air requirements of aero-engines with fewer stages while reducing engine weight and improving efficiency, is a promising solution.

[0003] However, angular separation within the compressor stator blades is a major obstacle to improving the single-stage pressure ratio while maintaining efficiency. It causes aerodynamic blockage, generates additional losses, and compromises compressor stability. Therefore, effectively suppressing angular separation is crucial for increasing the load on the compressor within an aero-engine.

[0004] The separation in the inner corner region of the compressor stator blades is mainly caused by three factors: the reverse pressure gradient in the flow direction, the intersection of the blade and the boundary layer on the endwall, and the lateral secondary flow caused by the circumferential pressure gradient and the low-velocity body near the hub. To address these three factors, researchers both domestically and internationally have proposed various flow control methods, including blade sweeping, blade rounding, blade blending, non-axisymmetric endwall modification, and vortex generators.

[0005] Eddy current generator technology is a flow control technique for transverse secondary flows caused by circumferential pressure gradients and low-velocity bodies near the hub. However, existing eddy current generator designs rely on global optimization methods, which are time-consuming, computationally intensive, and have low engineering usability. Therefore, there is an urgent need to propose a new eddy current generator design method. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings and defects of existing vortex generator design methods, and to solve the technical problems of long time consumption and large computational load caused by the reliance on global optimization methods in vortex generator design. A creative design method for an inner hub vortex generator of an axial compressor stator blade is proposed.

[0007] First, select the mounting location of the vortex generator on the hub, determining its axial and circumferential positions. Then, select the geometric parameters of the vortex generator, including its height and frontal area, determining its length and angle of attack. Finally, the length of the vortex generator is determined based on the selected frontal area and height.

[0008] Beneficial effects

[0009] The method of the present invention has the following advantages compared with the prior art:

[0010] 1. This invention does not require global optimization methods to optimize the eddy current generator scheme, which can save a lot of computation time and computational resources. Attached Figure Description

[0011] Figure 1 A schematic diagram showing the selection of the flow direction position for the eddy current generator;

[0012] Figure 2 A schematic diagram showing the selection of the circumferential position of the eddy current generator;

[0013] Figure 3 for Definition diagram;

[0014] Figure 4 Schematic diagram of the windward area of ​​the vortex generator;

[0015] Figure 5 This is a flow field diagram inside the final stage stator blades of a certain type of two-stage fan.

[0016] Figure 6 A diagram showing the effect of applying a vortex generator to the final stage stator blade according to the design method described in this patent. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0018] A design method for an inner hub vortex generator in the stator blades of an axial compressor includes the following steps:

[0019] Step 1: Select the mounting location of the eddy current generator on the wheel hub. This includes:

[0020] Step 1.1: Determine the axial position of the eddy current generator;

[0021] The axial position of the eddy current generator should be located at the starting separation point of the corner separation.

[0022] Step 1.2: Determine the circumferential position of the eddy current generator;

[0023] The circumferential position of the eddy current generator should be as close as possible to the suction surface of the stationary blades, while ensuring that the distance between it and the local suction surface is more than 5 times the thickness of the boundary layer of the suction surface.

[0024] Step 2: Select the geometric parameters of the eddy current generator. This includes:

[0025] Step 2.1: Select the height and windward area of ​​the vortex generator;

[0026] The height of the eddy current generator is selected according to the following formula:

[0027]

[0028] Among them, h VG The height of the eddy current generator. The height of the transverse secondary flow peak within the still blade channel;

[0029] The windward area of ​​the vortex generator is selected based on the intensity of the transverse secondary flow. The intensity of the transverse secondary flow is defined by the momentum integral of the transverse secondary flow.

[0030]

[0031] Among them, MO CF Flux is the momentum integral of the transverse secondary flow, ρ is the local fluid density, and V is the velocity. CF R is the transverse secondary flow velocity, γ is the angle between the local mainstream direction and the axial direction, and R is the cross-flow velocity. Hub The radius of the local wheel hub. Let be the radius where the transverse secondary flow velocity is 0, and AL be the dimensionless axial position of the stationary blade.

[0032] The windward area of ​​the eddy current generator is determined according to the following formula:

[0033]

[0034] Among them, A VG The frontal area of ​​the vortex generator is not its lateral area; V MS Before installing the eddy current generator, the mainstream velocity at the top position of the eddy current generator is to be determined.

[0035] Step 2.2: Determine the length and angle of attack of the eddy current generator.

[0036] The angle of attack of the eddy current generator is determined by the following formula:

[0037] α VG =10°~20° (4)

[0038] Where, α VG The angle of attack of the vortex generator is the angle between the velocity vector at the top of the vortex generator within the prototype stator passage and the direction of the vortex generator before its installation.

[0039] Ultimately, the length l of the eddy current generator VG Based on the selected vortex generator frontal area A VG Height h VG and angle of attack α VG Sure.

[0040] Example

[0041] This example describes a specific implementation scheme for designing an eddy current generator for the final stage stator blades of a certain type of two-stage fan using the method of the present invention.

[0042] Figure 1 A schematic diagram showing the selection of the flow direction position for the eddy current generator. Figure 2 A schematic diagram showing the selection of the circumferential position of the eddy current generator. Figure 3 for Definition diagram. Figure 4 This is a schematic diagram of the windward area of ​​the vortex generator. Figure 5 This is a flow field diagram inside the final stage stator blades of a certain type of two-stage fan. Figure 6 The diagram shows the effect of applying an eddy current generator to the final stage stator blade according to the design method described in this patent; based on this, a specific implementation of the invention in a particular application scenario is described.

[0043] A certain type of two-stage fan exhibits corner separation dominated by transverse secondary flow within the last-stage stator blades. The stator blade has an aspect ratio of 1.6, an airfoil angle of 57°, a designed maximum inlet Mach number of 0.83, an average diffusion factor of 0.6, and a consistency of 2.1. To suppress the transverse secondary flow, a vortex generator is designed in this example. First, the starting point of the corner separation is determined, and the vortex generator is positioned at this starting point, such as... Figure 1 As shown. Secondly, the circumferential position of the vortex generator should be selected, as close as possible to the suction surface, but the distance from the suction surface should be at least 5 times the local boundary layer thickness of the suction surface. Thirdly, the height of the vortex generator should be selected based on the average height of the crossflow peaks within the channel. The definition of the crossflow peak height is as follows... Figure 3 As shown. The height of the eddy current generator selected here is... Then, the windward area of ​​the vortex generator is selected based on the intensity of the transverse secondary flow within the channel, where the windward area of ​​the vortex generator is defined as follows: Figure 4 As shown. The vortex generator selected here has a windward area of ​​2.6 mm. 2 Next, the angle of attack of the vortex generator is selected; here, a 19° angle of attack is chosen. Finally, the length of the vortex generator is determined; here, the length is set to 3.3 mm. Without the vortex generator applied, the flow field inside the stator blade is as follows: Figure 5 As shown, the total pressure loss coefficient contour plots at various flow directions within the stator blade are also displayed. After applying the vortex generator according to the design method of this patent, the transverse secondary flow is suppressed, and the total pressure loss coefficient within the stator blade channel decreases, as shown... Figure 6 As shown.

Claims

1. A design method for an inner hub vortex generator in the stator blades of an axial compressor, characterized in that, Includes the following steps: Step 1: Select the mounting position of the eddy current generator on the wheel hub; Step 1.1: Determine the axial position of the eddy current generator; The axial position of the eddy current generator is located at the starting separation point of the corner separation; Step 1.2: Determine the circumferential position of the eddy current generator; The circumferential position of the eddy current generator should be as close as possible to the suction surface of the stationary blade, while ensuring that the distance between it and the local suction surface is more than 5 times the thickness of the boundary layer of the suction surface. Step 2: Select the geometric parameters of the eddy current generator; include: Step 2.1: Select the height and windward area of ​​the vortex generator; The height of the eddy current generator is selected according to the following formula: （1） in, The height of the eddy current generator. The height of the transverse secondary flow peak within the still blade channel; The windward area of ​​the vortex generator is selected based on the intensity of the transverse secondary flow; whereby the intensity of the transverse secondary flow is defined by the momentum integral of the transverse secondary flow: （2） in, This is the momentum integral of the transverse secondary flow. For the local fluid density, The transverse secondary flow velocity, The angle between the local mainstream direction and the axial direction. The radius of the local wheel hub. The radius where the transverse secondary flow velocity is 0. The dimensionless axial position of the stationary blade; The windward area of ​​the eddy current generator is determined according to the following formula: （3） in, The frontal area of ​​the vortex generator is not its lateral area; Before installing the eddy current generator, the mainstream velocity at the top position of the eddy current generator is to be determined. Step 2.2: Determine the length and angle of attack of the eddy current generator; The angle of attack of the eddy current generator is determined by the following formula: （4） in, The angle of attack of the vortex generator is the angle between the velocity vector at the top of the vortex generator in the prototype stator channel before the vortex generator is installed and the direction of the vortex generator. Ultimately, the length of the eddy current generator Based on the selected vortex generator frontal area ,high and attack angle Sure.

2. The design method of the hub vortex generator in the stator blade of an axial compressor as described in claim 1, characterized in that, The angle of attack of the eddy current generator is .

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