A corner styling design method based on styling shape factor

Abstract

A corner profile design method based on the shaping shape factor of the present invention belongs to the field of compressor design; the specific steps are as follows: obtaining the flow field information of the prototype compressor; parameterizing the suction surface of the compressor; constructing a control function for the circumferential variation of the corner profile suction surface; constructing a control function for the variation of the corner profile suction surface along the blade height direction; and constructing a three-dimensional corner profile function from the circumferential control function and the blade height control function. Combining the existing corner profile design methods, the present invention proposes a parametric corner profile method for improving the corner separation of a high-load axial compressor based on flow field information by introducing a circumferential variation control function and a variation control function along the blade height direction, and introducing a shaping shape factor to increase the diversity of shaping shapes. This corner profile method has a quantitative measurement rule, is flexible in shaping and easy to implement, and thus has broad application prospects in improving the corner separation of axial compressors and enhancing the overall performance of aeroengines.

Description

Technical Field

[0001] The present invention belongs to the field of compressor design, and particularly relates to a corner region shaping design method based on a shaping shape factor. Background Art

[0002] In recent years, with the increasingly stringent requirements for the performance of aero-engines, while pursuing a high thrust-to-weight ratio for aero-engines, the single-stage adverse pressure gradient of an axial compressor has increased. Under the action of a strong adverse pressure gradient, low-energy fluid in the corner region of the axial compressor accumulates continuously, forming a three-dimensional corner separation. The formation of the three-dimensional corner separation severely restricts the improvement of the performance of the axial compressor, such as pressure ratio, efficiency, and stall margin, which conflicts with the overall performance improvement goal of aero-engines. Therefore, effectively controlling the three-dimensional corner separation is a hot research issue for improving the internal flow of the axial compressor and enhancing the performance of aero-engines.

[0003] To effectively control the development of the three-dimensional corner separation, domestic and foreign scholars have applied the dihedral angle principle to improve the accumulation of low-energy fluid in the corner region. By directly shaping the corner region, the three-dimensional corner separation can be effectively controlled. In current research, there are two ways to change the angle between the suction surface and the end wall: The first way is to directly change the perpendicular relationship between the suction surface and the hub surface, so that the suction surface of the blade body forms an obtuse or acute angle with the end wall, without changing the blade thickness. The study of the first shaping method shows that when the angle between the suction surface of the blade body and the end wall is obtuse, the development of secondary flow and three-dimensional corner separation can be effectively inhibited; when the angle is acute, the three-dimensional corner separation develops into a larger corner stall. The development of the first shaping method has gradually improved and widely applied the dihedral angle principle. The second way is to fill or dig out some three-dimensional entities at the junction of the suction surface of the blade body and the end wall, so as to increase or decrease the local thickness of the blade. Based on the dihedral angle principle, the second shaping method is proposed. Compared with the first shaping method, the second shaping method changes the dihedral angle range by filling or digging out three-dimensional entities in the corner region, and can keep the dihedral angle changing flexibly from the leading edge to the trailing edge (the dihedral angle changes from small to large, from large to small, or in a wave shape from the leading edge to the trailing edge).

[0004] According to the above-mentioned corner area modeling method II, the research hot issues are mainly concentrated in the following two aspects: 1. Through experiments and numerical simulations, the control mechanism of corner area separation after filling or digging different three-dimensional entities is explored. 2. Through single-objective and multi-objective optimization of corner area modeling, the corner area modeling and flow field information data are mined to obtain the corner area optimization modeling changes with working conditions and its flow field control mechanism. According to existing literature records, based on the Frotran program, the compressor blades are parameterized, and the corner area optimization modeling is obtained by adjusting the maximum corner area modeling width and its position parameters. After experimental and numerical simulation verification, the corner area separation is effectively controlled. However, there are the following two disadvantages: 1. The modeling shape is single, and by adjusting the maximum modeling width and its position, only a single peak modeling (projected on the end wall) can be formed; 2. The modeling changes along the blade height direction are not considered, and there is a lack of shaping of the three-dimensional modeling structure. Summary of the invention

[0005] Technical issues to be solved:

[0006] In order to avoid the shortcomings of the prior art, the present invention provides a corner area modeling design method based on modeling shape factors, which quantitatively fills or digs out three-dimensional geometric shapes in the corner areas through control functions to solve the problem of the overall performance of the compressor being reduced due to corner area separation.

[0007] The technical solution of the present invention is: a corner area modeling design method based on modeling shape factor, characterized by the following specific steps:

[0008] Step 1: Obtain prototype compressor flow field information;

[0009] Step 2: parameterizing the suction surface of the compressor;

[0010] Step 3: construct a control function for the corner area suction surface changing along the circumferential direction;

[0011] Step 4, constructing a control function for the change of the suction surface of the corner area along the blade height direction;

[0012] Step 5: Construct the entire three-dimensional corner area modeling function based on the circumferential control function and blade height control function obtained in steps 3 and 4.

[0013] A further technical solution of the present invention is: in the step 1, the corner separation area information is obtained by analyzing the compressor end wall-suction surface streamline topology map, high dissipation distribution cloud map and low energy fluid.

[0014] A further technical solution of the present invention is: in the step 2, the specific parameterization is to divide the suction surface of the blade along the blade height direction into 12 Besizer control lines, and the Besizer control line function is:

[0015]

[0016] where P i is the value of the control point on the Besizer curve, n is the order of the Besizer curve, and t is the parameter. The control function constructs the corner region shape by controlling the points on the Besizer curve.

[0017] A further technical solution of the present invention is that in the step 3, the circumferential control function is superimposed on the 12 Besizer curves obtained by parameterization in the step 2, and the circumferential control function adopts a third-order Fourier function:

[0018]

[0019] where d m , d n , θ m , θ n are the amplitude and shape coefficient for controlling K(z), m = 0, 1, 2; n = 0, 1, 2; is the curve length of the entire suction surface modeling area.

[0020] A further technical solution of the present invention is that when the control shape is a single-peak shape, the shape control factor of the shape is:

[0021]

[0022] A further technical solution of the present invention is that when the control shape curve has two peaks and is concave at the leading edge and convex at the trailing edge, the shape control factor of the shape is:

[0023]

[0024] A further technical solution of the present invention is that when the control shape curve has two peaks and is convex at the leading edge and concave at the trailing edge, the shape control factor:

[0025]

[0026] A further technical solution of the present invention is that when the control shape curve has three peaks, and is convex at both ends and concave in the middle, and the minimum value of the concavity is not less than zero, then the shape control factor:

[0027]

[0028] A further technical solution of the present invention is that in the step 4, the control function for the change in the blade height direction is:

[0029]

[0030] where a0 is the inverse proportional coefficient, Dcos 3 (b1x 2+(b2x + b3) is a smooth function.

[0031] A further technical solution of the present invention is that in the step 5, the three-dimensional corner region shaping function is:

[0032]

[0033] Beneficial effects

[0034] The beneficial effects of the present invention are as follows: Combining the existing corner region shaping design method, the present invention proposes a parametric corner region shaping method for improving the corner separation of a high-load axial compressor based on flow field information by introducing a circumferential variation control function and a variation control function along the blade height direction, and introducing a shaping shape factor to increase the diversity of shaping shapes. This corner region shaping method has a quantitative measurement rule, is flexible in shaping and easy to implement, so it has broad application prospects in improving the corner separation of axial compressors and enhancing the overall performance of aeroengines.

[0035] Through the calculation of the total pressure loss of a high-load axial compressor with corner region shaping under the design condition and the near-stall condition, Table 1 shows the total pressure loss percentage at 40% of the axial chord length downstream of the trailing edge of a certain high-load axial compressor under different shaping shape factors. It is determined that the corner region shaping obtained by this corner region shaping formula and different shaping factors can effectively improve the internal flow field of the compressor. And the degrees of reducing the total pressure loss under the design condition and the near-stall condition are different under different shaping factors.

[0036] Table 1

[0037]

[0038] Figure 3 Shows the overall shaping effect diagram after adding a circumferential control function and a control function along the blade height at the junction of the suction surface of the blade body and the end wall. Improving the corner separation degree and enhancing the compressor performance depend on the parameter changes of the circumferential control function and the control function along the blade height. This shaping method enables quantitative analysis of the three-dimensional geometric shapes of filling and excavation with the flow field information and control mechanism. Description of the drawings

[0039] Figure 1 is the technical roadmap of the present invention;

[0040] Figure 2 is a schematic diagram of the corner separation region and the high-dissipation region of a certain high-load compressor in the present invention;

[0041] Figure 3 is a schematic diagram of the three-dimensional geometry filled or excavated on the suction surface of the blade in the present invention;

[0042] Figure 4 is a parametric schematic diagram of the corner region shaping of the present invention;

[0043] Figure 5(a) is a three-dimensional schematic diagram of the blade with corner shaping in the present invention;

[0044] Figure 5(b) is a schematic diagram of the distribution of control points on the suction surface besizer control line in the present invention;

[0045] Figure 5(c) is a schematic diagram of the projection of the corner shaping on the hub in the present invention;

[0046] Figure 5(d) shows the curvature change of the shaping along the blade height in the present invention;

[0047] Figure 6 It is a schematic diagram of the projection of the corner shaping on the hub after introducing the shaping factor in the present invention. Detailed implementation manners

[0048] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0049] To further verify the detailed steps and advantages of the implementation of the present invention, the following will be described in combination with the accompanying drawings and examples.

[0050] The purpose of the present invention is to quantify the three-dimensional geometry size and shape filled or excavated in the corner shaping through parameterization and function control, and directly adjust the shape of the corner shaping according to the internal flow field information of the axial compressor under various working conditions, so as to weaken or eliminate the corner separation of the compressor, reduce the total pressure loss, and improve the overall performance of the compressor.

[0051] Figure 1 Shown below is the technical roadmap of a corner shaping method for improving the corner separation of a compressor disclosed in the present invention. Taking a certain high-subsonic high-load axial compressor (design parameters are shown in Table 1) as an example, the control effect of the corner shaping on the corner separation is verified by numerical simulation. Table 2 shows the design parameters of the high-subsonic high-load axial compressor.

[0052] Table 2

[0053]

[0054]

[0055] Taking this as an example, the specific implementation steps are as follows:

[0056] Step 1: Obtain the corner separation structure of the compressor

[0057] By analyzing the streamline topology diagram of the compressor end wall - suction surface, the high-dissipation distribution cloud diagram, and the low-energy fluid analysis ( Figure 2 ), obtain the information of the corner separation area, laying a foundation for constructing a corner shaping that can effectively weaken or eliminate the corner separation.

[0058] Step 2: Parametric Method for Corner Region Modeling

[0059] Parametrize the compressor suction surface. Specifically, the suction surface of the blade is divided into 12 Bezier control lines along the blade height direction ( Figure 4 ), and the Bezier control line function is:

[0060]

[0061] where P i is the value of the control point on the Bezier curve (Figure 5(b)), n is the order of the Bezier curve, and t is the parameter. The control function completes the corner region modeling construction by controlling the points on the Bezier curve.

[0062] Step 3: Construct the Control Function for the Circumferential Variation of the Suction Surface of the Corner Region Modeling

[0063] Figure 4 Figure 5(d) shows the overall detailed structure of the corner region modeling. Figure 5(c) shows the modeling perturbation of the suction surface by the circumferential control function on the hub cross-section. The circumferential control function uses a third-order Fourier function:

[0064]

[0065] where d m , d n , θ m , θ n (m = 0, 1, 2; n = 0, 1, 2) are the amplitude and shape coefficients for controlling K(z). is the curve length of the entire suction surface modeling region. The third-order Fourier function can effectively express various modeling curves. To effectively control the shape change of the modeling, a modeling shape factor is introduced. The modeling shape factor can effectively control the concave, convex, and peak numbers of the modeling curve shape by controlling the number of zeros of K(z) and its first and second derivatives. When the controlled modeling is a single-peak modeling, the modeling shape control factor ( Figure 6 (a)) is:

[0066]

[0067] If the controlled modeling curve is to have two peaks with a depression at the leading edge and a bulge at the trailing edge, then the above modeling shape control factor ( Figure 6 (b)) is:

[0068]

[0069] When the projection of the controlled modeling curve on the hub has two peaks with a bulge at the leading edge and a depression at the trailing edge, the shape control function ( Figure 6 (c)) is:

[0070]

[0071] For the high-load axial compressor in this example, through numerical simulation and flow field analysis, it is proved that when the control profile curve (Figure 5(c)) has a single peak or has a double peak with a depression at the leading edge and a bulge at the trailing edge, the control effect on the corner separation at the design point operating condition is relatively significant.

[0072] If the profile is made to have a triple peak, with bulges at both ends and a depression in the middle, and the minimum value of the depression is not less than zero, then the profile shape control factor ( Figure 6 (d)) is:

[0073]

[0074] Step 4: Construct the control function for the variation of the suction surface of the corner profile along the blade height direction

[0075] Control the variation of the corner profile along the blade height direction through an inverse proportional function (Figure 5(d)). The change of the inverse proportional coefficient a0 can control the curvature of filling or scooping the surface

[0076]

[0077] On the other hand, since the curve of the variation along the blade height direction is controlled by B-spline, it is necessary to ensure the smoothness of the profile by adding a smoothing function Dcos 3 (b1x 2 +b2x + b3). Therefore, the control function in the blade height direction can be further written as:

[0078]

[0079] Step 5: From the circumferential control function and the blade height control function (1)(2)(7)(8) described in Step 3 and Step 4, construct the entire three-dimensional corner profile function as:

[0080]

[0081] Based on the numerical simulation of the compressor, this invention obtains the information of the corner separation region through the streamline topology diagram of the endwall-suction surface, the high-dissipation distribution nephogram, and the low-energy fluid analysis. At the same time, by adjusting the profile control function, a corner profile structure beneficial to the control of the corner separation of the compressor is obtained.

[0082] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and purposes of the present invention.

Claims

1. A corner styling design method based on a styling shape factor, characterized in that The specific steps are as follows: Step 1: Obtain the flow field information of the prototype compressor; Step 2: Parametrize the suction surface of the compressor; Step 3: Construct a control function for the circumferential variation of the corner-shaped suction surface; Step 4: Construct a control function for the variation of the corner-shaped suction surface along the blade height direction; Step 5: Construct the entire three-dimensional corner-shaped modeling function from the circumferential control function and the blade-height control function obtained in Step 3 and Step 4; In Step 2, the specific parametrization is to divide the blade suction surface into 12 Bezier control lines along the blade height direction, and the Bezier control line function is: （1） Where P i is the value of the control point on the Besizer curve, n is the order of the Besizer curve, t is a parameter; the control function completes the construction of the corner area shape by controlling the points on the Besizer curve; In Step 3, the circumferential control function is superimposed on the 12 Bezier curves obtained by parametrization in Step 2, and the circumferential control function uses a third-order Fourier function: （2） Among them , , , To control the amplitude and shape factor of K(z), m = 0, 1, 2; h = 0, 1, 2; is the curve length of the entire suction surface modeling area; When the control shape is a single-peak shape, the shape control factor is: （3） When the control shape curve has two peaks with a depression at the leading edge and a bulge at the trailing edge, the shape control factor is: （4） When the control shape curve has two peaks with a bulge at the leading edge and a depression at the trailing edge, the shape control factor: （5） When the control shape curve has three peaks with bulges at both ends and a depression in the middle, and the minimum value of the depression is not less than zero, the shape control factor: （6） In Step 4, the control function for the variation along the blade height direction is: Among them, is the inverse proportional coefficient, is a smooth function; In Step 5, the three-dimensional corner-shaped modeling function is: 。 2. The angular region styling design method based on the styling shape factor according to claim 1, wherein: In Step 1, the corner separation region information is obtained by analyzing the compressor end wall-suction surface streamline topology diagram, high-dissipation distribution cloud diagram, and low-energy fluid.

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