Design method for asymmetric leading edge diffuser structure
Through the asymmetric leading edge diffuser structure design method, the leaf type loss problem caused by large and discontinuous leading edge curvature in the centrifugal compressor is solved, and the leaf type loss and available angle of attack range are significantly improved, and the efficiency of the centrifugal compressor is improved.
Patent Information
- Application Number
- CN202411666107.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-20
- Publication Date
- 2025-02-28
AI Technical Summary
In the prior art, the leading edge curvature of the centrifugal compressor is large and discontinuous, causing excessive expansion of the air flow, resulting in the leading edge pressure distribution suction peak, and causing leaf type loss.
The asymmetric leading edge diffuser structure design method is adopted, and the mid-arc function is obtained by designing the diffuser blade type of the symmetric leading edge, and the thickness distribution of the suction surface and pressure surface is obtained based on it. The leading edge part of the leaf thickness distribution is fitted using any surface molding method to obtain the coefficient value of the fitted polynomial, and then a new shape function and thickness distribution are obtained to form a new asymmetric leading edge leaf pattern.
Through the asymmetric leading edge design, the blade loss and available angle of attack of the diffuser are significantly improved, thereby improving the efficiency of the centrifugal compressor.
Smart Images
Figure CN119538449A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of turbocharger compressors, and in particular to a method for designing an asymmetric leading edge diffuser structure. Background Art
[0002] Centrifugal compressors have been widely used in superchargers due to their advantages of high single-stage pressure ratio, wide operating range, simple and compact structure, few parts, and high reliability, and vaned diffusers are widely used in high-pressure ratio centrifugal compressors. The leading edge is the starting point of the flow on the diffuser blade surface. Its blade shape is directly related to the development of the surface boundary layer along the blade surface and the downstream flow field structure, and plays a vital role in the stable operation of the entire centrifugal compressor.
[0003] The large and discontinuous leading edge curvature causes excessive expansion of the airflow, resulting in a suction peak in the leading edge pressure distribution, which is one of the main causes of blade loss. By rationally designing the leading edge profile, the leading edge curvature distribution can be improved, the curvature can be continuous, the suction peak can be weakened, the separation bubble can be controlled, and the aerodynamic performance of the blade can be improved. The existing leading edge modeling method is a symmetrical structure of the suction surface and the pressure surface. For the diffusers of some high-pressure ratio centrifugal compressors, the leading edge pressure surface is separated under special working conditions. The leading edges on both sides are designed asymmetrically to weaken the flow separation on the pressure surface, thereby improving the aerodynamic performance of the entire centrifugal compressor. Summary of the invention
[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for designing an asymmetric leading edge diffuser structure to improve the efficiency of a centrifugal compressor.
[0005] The object of the present invention is achieved in that:
[0006] A design method for an asymmetric leading edge diffuser structure.
[0007] Design a diffuser blade profile with a symmetrical leading edge and obtain the camber function of the blade profile;
[0008] The thickness distribution of the suction surface and the pressure surface is obtained based on the mid-arc function;
[0009] The leading edge of the blade thickness distribution is fitted using an arbitrary surface modeling method to obtain the values of the coefficients in the fitting polynomial, and then the shape function of the diffuser blade and the distribution of the leading edge shape function are obtained. The shape function S(x / c) of the diffuser blade is:
[0010]
[0011] The boundary conditions for this shape function are:
[0012]
[0013] In the formula, R LE represents the curvature radius of the leading edge, β represents the cutting angle of the trailing edge, and H TE Represents the semi-thickness of the trailing edge; From the above formula, it can be seen that the boundary conditions of the shape function are directly related to the leading edge radius and the trailing edge shape, so the shape function can control the modeling process;
[0014] By changing the coefficient R LE , β, H TE The value of is used to obtain a new shape function, thereby obtaining a new thickness distribution;
[0015] Applying the new thickness distribution to the camber function results in a new asymmetric leading edge blade profile.
[0016] Preferably, a leading edge thickness distribution diagram is drawn, wherein the abscissa represents the chord length L, and the ordinate represents the blade profile half thickness M. The shape design is performed for the first 10% of the chord length segment, and the variables are defined as follows:
[0017]
[0018] Where S 0.1C It represents the total arc length of the median arc corresponding to the first 10% of the axial chord length, and the independent variable ψ satisfies 0≤ψ≤1; and also satisfies the following boundary conditions:
[0019]
[0020] In the formula, R LE represents the curvature radius of the leading edge, β represents the cutting angle of the trailing edge, and H TE Indicates the half thickness of the trailing edge; thereby controlling the curvature of the leading edge point and the continuity of the trailing edge curvature and the blade body curvature.
[0021] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:
[0022] Due to the asymmetric leading edge design, the diffuser blade loss and available angle of attack range are significantly improved, thereby improving the efficiency of the centrifugal compressor. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is the comparison chart of total pressure loss coefficient;
[0024] Figure 2 Schematic diagram of asymmetric leading edge;
[0025] Figure 3 Schematic diagram of leading edge thickness distribution. DETAILED DESCRIPTION
[0026] 1. When designing a diffuser blade with a symmetrical leading edge, the camber function of the blade is obtained;
[0027] 2. Obtain the thickness distribution of the suction surface and pressure surface based on the mid-arc line;
[0028] 3. Use the arbitrary surface modeling method to fit the leading edge portion (such as the first 15%) of the blade thickness distribution, so as to obtain the values of each coefficient in the fitting polynomial and the distribution of the leading edge shape function.
[0029] 4. By appropriately changing the coefficient R LE , β, H TE By changing the value of , a new shape function can be obtained, and thus a new thickness distribution can be obtained. Applying the new thickness distribution to the mid-camber line can obtain a new asymmetric leading edge blade profile, see Figure 2 .
[0030] Comparing the original blade type with the blade type with asymmetric leading edge, the total pressure loss is shown in Figure 1 .from Figure 1 It can be seen that due to the asymmetric leading edge design, the diffuser blade loss and available angle of attack range have been significantly improved, thus improving the efficiency of the centrifugal compressor.
[0031] Specifically:
[0032] Shape function S(x / c):
[0033]
[0034] The boundary conditions for this shape function are:
[0035]
[0036] In the formula, R LE represents the curvature radius of the leading edge, β represents the cutting angle of the trailing edge, and H TE It can be seen from the above formula that the boundary conditions of the shape function are directly related to the leading edge radius and the trailing edge shape, so the shape function can directly and accurately control the modeling process.
[0037] Figure 3 This is a schematic diagram of the leading edge thickness distribution, where the horizontal axis represents the chord length L, and the vertical axis represents the blade half thickness M. The shape design is performed for the first 10% of the chord length segment. At this time, the variables are defined as follows:
[0038]
[0039] Where S 0.1C It represents the total arc length of the median arc corresponding to the first 10% of the axial chord length, and the independent variable ψ satisfies 0≤ψ≤1. At the same time, it satisfies the following boundary conditions:
[0040]
[0041] In the formula, RLE represents the curvature radius of the leading edge, β represents the cutting angle of the trailing edge, and H TE Indicates the half thickness of the trailing edge. This makes it easy to control the curvature of the leading edge point and the continuity of the trailing edge curvature and the blade body curvature.
[0042] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.
Claims
1. A method for designing an asymmetric leading edge diffuser structure, characterized in that: Design a diffuser blade profile with a symmetrical leading edge and obtain the camber function of the blade profile; The thickness distribution of the suction surface and the pressure surface is obtained based on the mid-arc function; The leading edge of the blade thickness distribution is fitted using an arbitrary surface modeling method to obtain the values of the coefficients in the fitting polynomial, and then the shape function of the diffuser blade and the distribution of the leading edge shape function are obtained. The shape function S(x / c) of the diffuser blade is: The boundary conditions for this shape function are: In the formula, R LE represents the curvature radius of the leading edge, β represents the cutting angle of the trailing edge, and H TE Represents the semi-thickness of the trailing edge; From the above formula, it can be seen that the boundary conditions of the shape function are directly related to the leading edge radius and the trailing edge shape, so the shape function can control the modeling process; By changing the coefficient R LE , β, H TE The value of is used to obtain a new shape function, thereby obtaining a new thickness distribution; Applying the new thickness distribution to the camber function results in a new asymmetric leading edge blade profile.
2. The method for designing an asymmetric leading edge diffuser structure according to claim 1, characterized in that: Draw a leading edge thickness distribution diagram, where the horizontal axis represents the chord length L, and the vertical axis represents the blade half thickness M. The shape design is performed for the first 10% of the chord length segment. At this time, the variables are defined as follows: Where S 0.1C It represents the total arc length of the median arc corresponding to the first 10% of the axial chord length, and the independent variable ψ satisfies 0≤ψ≤1; and also satisfies the following boundary conditions: In the formula, R LE represents the curvature radius of the leading edge, β represents the cutting angle of the trailing edge, and H TE It indicates that the caudal margin is semi-thick; This controls the curvature of the leading edge point, the curvature of the trailing edge, and the curvature of the blade profile and blade body to be continuous.