A blade local roughening design method for transonic compressor performance improvement

Abstract

The present application belongs to the field of aero-engine compressor aerodynamic design and flow control technology, and particularly relates to a partial roughening design method for a transonic compressor rotor blade. The present application achieves the purpose of improving the aerodynamic performance by reasonably performing partial roughening design on the surface of the transonic compressor blade, and provides technical support for fine design of high-performance transonic compressors. The present application includes determining a roughness addition area, setting roughness size, roughening, and smoothing the boundary between the smooth area of the blade and the roughened addition area to obtain a target blade with partial roughening. The present application realizes flow regulation in the shock layer interference area by partial roughening treatment of the blade tip shock sensitive area, thereby significantly improving the stall margin of the compressor without losing the performance of the design condition.

Description

Technical Field

[0001] This invention belongs to the field of aerodynamic design and flow control technology of aero-engine compressors, specifically relating to a blade local roughening design method for improving the performance of transonic compressors. Background Technology

[0002] The pressurization capacity of transonic axial compressors is highly dependent on the orderliness of the shock-leakage vortex coupled flow in the blade tip region. Experimental and high-resolution numerical studies have shown that this local flow can contribute 20%–30% of the total stage power loss, decisively influencing the stall margin. The aerodynamic performance of transonic compressor blades is extremely sensitive to changes in geometry. In the operating environment, dust erosion, foreign object impacts, and corrosion often increase the roughness of the blade suction surface by tens of micrometers, resulting in aerodynamic performance degradation. This sensitivity to minute geometric changes is even more pronounced in transonic compressor flows exhibiting shock-boundary layer interference. Due to the high aerodynamic responsiveness of transonic compressor blades to roughness micro-undulations, aerodynamic performance can be improved by designing roughening of the sensitive tip region and inversely controlling the tip flow.

[0003] Researchers have previously divided blade suction into three equal parts (forward, middle, and rear) to study the impact of roughness location on blade aerodynamic performance, finding that different roughness distributions have varying effects on different flow parameters. Studies have shown that roughness distributed in the compressor leading edge region has a more significant impact on overall performance than roughness distributed in the trailing edge region. By investigating the effects of surface roughness on aerodynamic performance and internal flow field at low Reynolds numbers, researchers have found that surface roughness can promote transition, suppress laminar separation, and alter velocity and static pressure distributions, thereby improving the compressor flow field and aerodynamic characteristics. Researchers have experimentally studied the interaction between roughness and the shock wave boundary layer in compressor stage blade passages, finding that the closer to the shock wave, the larger the applied roughness size can be, and the effectiveness of applied roughness in reducing wake losses significantly increases. Appropriate roughness setting is an effective passive control method for improving the flow characteristics of transonic compressors.

[0004] The purpose of this invention is to transform unavoidable surface roughness into a controllable flow regulation method. It actively utilizes the disturbance effect of roughness on local flow structures to achieve precise control of complex flows within transonic compressors, particularly in the tip shock-boundary layer interference region. Furthermore, it resolves the contradiction between the high pressure ratio design and the wide stall margin requirement of high-load transonic compressors. By introducing designed roughness into specific regions of the blade suction surface, the stable operating range of the compressor is significantly widened without reducing or essentially maintaining the design pressure ratio and efficiency. Numerical calculations have been completed under typical high Mach number cruise conditions, revealing the influence of roughness on pressure ratio, efficiency, and stall margin, providing a theoretical basis for the development of passive flow control for compressors based on blade surface roughening.

[0005] Therefore, there is a need to provide a blade local roughening design method for improving the performance of transonic compressors. Summary of the Invention

[0006] While existing methods have good applications in overall engine performance analysis, their applicability to transition regions and complex three-dimensional topologies is significantly limited in the fully rough flow domain. This invention provides a method for local roughening flow control of transonic compressor blades. By implementing three-dimensional random roughening design in specific regions of the blade, flow regulation in the shock wave and boundary layer interference regions is achieved, thereby significantly improving and widening the compressor stall margin without sacrificing design performance.

[0007] The present invention provides a blade local roughening design method for improving the performance of transonic compressors, which adopts the following technical solution, including: The roughening addition region is defined based on the interference region of the shock wave and the boundary layer; Set the roughness value for the roughening addition area, and perform initial roughening on the original blade roughening addition area on the blade thickness by removing material; The target blade with local roughening is obtained by smoothing the boundary between the roughened region and the smooth region after initial roughening.

[0008] A further technical solution of the present invention is to use the shock wave and boundary layer interference region as the roughening addition region.

[0009] A further technical solution of the present invention is the step of obtaining the interference region between the shock wave and the boundary layer: Numerical simulation calculations were performed on the original blade to obtain Mach number cloud maps of the original blade at different height sections; The height range where the shock wave appears is defined as the height of the interference region between the shock wave and the boundary layer. The extent to which the shock wave affects the suction surface of the blade in the Mach number cloud diagram is taken as the length of the interference region between the shock wave and the boundary layer.

[0010] A further technical solution of the present invention is that the length range of the roughening addition region in the blade height direction is... , ,in, Indicates blade height; This represents the length of the cross section from the blade root at the initial location of the shock wave in the numerical simulation; the location where roughness is added. ,in, This indicates the location where the shock wave hits the suction surface of the blade; This indicates the range of influence of the shock wave on the suction surface of the blade.

[0011] A further technical solution of the present invention is as follows: ; This indicates the chord length of the blade.

[0012] A further technical solution of the present invention is that the expression for setting the roughness magnitude of the roughened region is:

[0013] In the formula, This indicates the roughness set in the roughening area; This represents a proportional parameter that limits the surface roughness thickness. Indicates the location where roughness is added; Represents a constant; This represents the angular frequency of the trigonometric function used to generate irregular random roughness; This represents the angular frequency of the trigonometric function used to generate irregular random roughness; This represents the phase of the trigonometric function used to generate irregular random roughness.

[0014] A further technical solution of the present invention is to limit the ratio parameter of the roughness thickness. satisfy Remove the maximum height of the material. , This indicates the local leaf thickness.

[0015] A further technical solution of the present invention is that the step of smoothing the boundary between the roughened region and the smooth region after initial roughening to obtain a locally roughened target blade is as follows: The boundary between the roughened region and the smooth region after initial roughening is smoothed by using a transition function to obtain the target blade with local roughening. The roughness of the target blade for local roughening is:

[0016] In the formula, This represents the roughness value after smoothing. Represents the transition function; This indicates the roughness set in the roughening area; This indicates the relative position where roughness is added during the transition from a smooth region to a roughened region; This indicates the relative position where roughness is added during the transition from a roughened area to a smooth area; Indicates the location where roughness is added; This indicates the location where the shock wave hits the suction surface of the blade; This indicates the range of influence of the shock wave on the suction surface of the blade; It represents a higher-order small quantity.

[0017] A further technical solution of the present invention is that the transition function is:

[0018] In the formula, For transition function, This indicates the relative position where roughness is added to the roughening area.

[0019] The beneficial effects of this invention are: This invention achieves flow control in the interference region between shock waves and the boundary layer by arranging random roughness bands in the shock wave sensitive area of ​​the blade tip. This roughening treatment significantly improves the compressor stall margin without sacrificing design performance. Based on actual blade geometry, this method can be integrated into existing compressor design and optimization processes, possessing engineering transfer potential. It transforms roughness, traditionally considered a "negative factor," into a "controllable flow regulation method," providing a new approach to compressor aerodynamic design. Specifically, this invention defines the range of roughness to be added to transonic compressor blades, providing reliable guidance for controlled roughness design. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram showing the influence range of the shock wave on the suction surface of the blade in this invention; Figure 2 This is a schematic diagram illustrating the domain division of the roughness piecewise function in this invention; Figure 3 This is a schematic diagram of the transition function in an embodiment of the present invention; Figure 4 This is a schematic flowchart of a blade local roughening design method for improving the performance of transonic compressors according to the present invention. Figure 5 This is a schematic diagram of the RANS (Reynolds average) calculation results for a transonic rotor Rotor37 blade in an embodiment of the present invention. Figure 6 This is a visualization result of the local roughening design of a transonic rotor Rotor37 blade in an embodiment of the present invention; Figure 7 This is a schematic diagram comparing the boost ratios of smooth and rough blades at high Reynolds numbers in an embodiment of the present invention. Figure 8 This is a schematic diagram comparing the efficiency of smooth blades and rough blades at high Reynolds numbers in an embodiment of the present invention. Detailed Implementation

[0022] 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.

[0023] This invention provides an embodiment of a blade local roughening design method for improving the performance of transonic compressors. The purpose of this embodiment is to transform unavoidable surface roughness into a controllable flow regulation mechanism. It actively utilizes the disturbance effect of roughness on the local flow structure to achieve precise control of complex flows within the transonic compressor, particularly the tip shock-boundary layer interference region. It also resolves the contradiction between the high pressure ratio design and the wide stall margin requirement of high-load transonic compressors. By introducing designed roughness in a specific region of the blade suction surface, the stable operating range of the compressor is significantly widened without reducing or essentially maintaining the design pressure ratio and efficiency. Numerical calculations have been performed under typical operating conditions such as high Mach number cruise and high-altitude low Reynolds number, revealing the influence of roughness on pressure ratio, efficiency, and stall margin. This provides a theoretical basis for the development of passive flow control for compressors based on blade surface roughening. Specifically, this embodiment uses the surface roughening of a transonic rotor Rotor37 blade as an example to illustrate the technical solution of this invention. Figure 4 As shown, it includes: S1. Determine the area to be roughened; Specifically, a roughening addition region is set based on the interference region of the shock wave and the boundary layer.

[0024] For example, in one specific embodiment, shock wave and boundary layer interference is a significant flow characteristic for transonic rotor blades. This physical phenomenon is highly sensitive to minute geometric changes on the blade surface. Existing research indicates that under the influence of a strong adverse pressure gradient from the shock wave, the interference between the boundary layer and the shock wave can cause boundary layer separation and the breakup of leakage vortices, leading to channel blockage and becoming a major cause of instability. Therefore, in this embodiment, the shock wave and boundary layer interference region is treated as a roughening addition region, with the aim of reducing the intensity of the shock wave within the boundary layer, thereby enhancing the turbulent boundary layer's resistance to separation and ultimately improving performance.

[0025] For example, in one specific embodiment, the steps for obtaining the interference region between the shock wave and the boundary layer are as follows: Numerical simulation calculations are performed on the original blade to obtain Mach number contour maps of the original blade at different heights; the height range where the shock wave occurs is determined as the height of the interference region between the shock wave and the boundary layer; the range of the blade's suction surface affected by the shock wave in the Mach number contour map is taken as the length of the interference region between the shock wave and the boundary layer. Wherein, the range of the blade's suction surface affected by the shock wave in the Mach number contour map is as follows: Figure 2 As shown.

[0026] For example, in one specific embodiment, numerical simulation of the original three-dimensional blade yields RANS (Reynolds average) results. The interference region between the shock wave and the boundary layer covers 70%–100% of the blade height. Therefore, the length range of the roughening addition region in the blade height direction is [missing information]. , ,in, Indicates blade height; This represents the length of the cross section from the blade root where the initial location of the shock wave appears in the numerical simulation calculation, such as... Figure 1 and Figure 2 As shown, the location where roughness is added. ,in, This indicates the location where the shock wave hits the suction surface of the blade; Indicates the range of influence of the shock wave on the suction surface of the blade, such as Figure 5 As shown in the figure, in this embodiment, the location of the shock wave is... Select here Therefore, the range of the flow direction .

[0027] S2. Set the roughness value and perform roughening; Specifically, a roughness value is set for the roughening addition area, and the roughening addition area of ​​the original blade is initially roughened on the blade thickness by removing material.

[0028] It should be noted that roughness is a measure of the microscopic unevenness of a surface and a quantitative method for describing surface morphology and profile. The profile characteristics of a rough surface are closely related to its surface properties, exhibiting three-dimensionality and randomness. This embodiment only discusses the statistical characteristics of roughness and does not require specific methods for achieving its three-dimensionality and randomness. Existing research has used equivalent gravel models built into commercial software to simulate blade surface roughness by increasing the turbulence length. Methods based on geometric deformation of randomly distributed rough surfaces and methods based on multiple cosine function roughness modeling can all achieve the construction of roughness with statistical characteristics. However, the roughness in this embodiment is achieved by removing material from the roughened distribution region on the basis of the original blade, rather than adding material. This is to avoid reducing the effective flow area of ​​the flow channel during flow control. Considering the structural strength of the blade, the roughness needs to be controlled within a reasonable range; otherwise, too much material removal will cause local stress concentration and lead to fracture.

[0029] For example, in one specific embodiment, considering that the blade thickness varies from the leading edge to the tip, the roughness requirements for this region also differ. In this embodiment, the roughness is set to be proportional to the local blade thickness, and the maximum reduction height is... Roughness set as the area to be roughened Furthermore, the maximum height reduction does not exceed 20% of the local thickness of the blade, which is the roughness at a certain location in the roughening area. ,in, This represents a proportional parameter that limits the surface roughness thickness. , This indicates the local blade thickness. Since the blade thickness is continuously varied in current blade designs, this indirectly ensures that the surface roughness is continuously varied. (The maximum height after removing material parameters is considered.) .

[0030] For example, in this embodiment, the expression for setting the roughness of the roughened area is:

[0031] In the formula, This indicates the roughness set in the roughening area; This represents a proportional parameter that limits the surface roughness thickness. Indicates the location where roughness is added; Represents a constant; This represents the angular frequency of the trigonometric function used to generate irregular random roughness; This represents the angular frequency of the trigonometric function used to generate irregular random roughness; This represents the phase of the trigonometric function used to generate irregular random roughness. Considering blade strength, 20% of the local blade thickness is selected, meaning the maximum reduction height does not exceed 20% of the local blade thickness. ).

[0032] S3. Smooth the boundary between the smooth area and the roughened area of ​​the blade to obtain the target blade with local roughening. Specifically, by combining the transition function with local roughening design, the following can be obtained: Figure 6 The target blade is shown with localized roughening.

[0033] For example, in one specific embodiment, local roughening design not only requires a given target roughness amplitude distribution within the roughened region, but also requires smoothing the boundary between the roughened and smoothed regions. If a "step-like" assignment is directly applied at the roughened region boundary, it will lead to abrupt spatial changes in geometric and equivalent roughness parameters: on the one hand, it may introduce local stress concentration (especially detrimental to thin-walled blades); on the other hand, it can easily generate additional losses in flow, thereby weakening the goal of improving performance through roughening. Therefore, in this embodiment, a continuously differentiable transition function is introduced in the rough-smooth boundary region, allowing the roughness amplitude to smoothly increase from zero to the target value, ensuring a slow change and geometric continuity in the roughness distribution. Specifically, in this embodiment, the roughness of the roughened region is multiplied by the transition function to obtain the roughness of the target blade. The roughness of the target blade with local roughening is:

[0034] In the formula, This represents the roughness value after smoothing. Represents the transition function; This indicates the roughness set in the roughening area; This indicates the relative position where roughness is added during the transition from a smooth region to a roughened region; This indicates the relative position where roughness is added during the transition from a roughened area to a smooth area; Indicates the location where roughness is added; This indicates the location where the shock wave hits the suction surface of the blade; This indicates the range of influence of the shock wave on the suction surface of the blade; It represents a higher-order small quantity.

[0035] The transition function is:

[0036] In the formula, For transition function, This indicates the relative position where roughness is added to the roughening area; it should be noted that in this embodiment, as... Figure 3 As shown, the transition function is a typical cubic polynomial, and the function value and first derivative are continuous at the breakpoint, thus ensuring the smoothness of the transition. Abrupt changes in slope occur at the boundary of the disease wall.

[0037] The following combination Figures 7-8 The aerodynamic effects of adding roughness to a target three-dimensional blade were verified: like Figure 7 As shown in Table 1, after blade roughening, the single-stage pressure ratio decreases under both low-flow and design-flow conditions. Dimensionally, using the design flow rate, the pressure ratio decreases by a maximum of 1.3% at near-stall and design flow rates. At flow rates between these two, the pressure ratio decrease is not significant. The peak flow rate shifts towards lower flow rates. Between the design and peak flow rates, the pressure ratio values ​​are similar. Furthermore, after roughening, the peak flow rate of the roughened blade increases by 0.36% compared to the smooth blade. From a stall margin perspective, the stall margin after increasing roughness is 11.41%, while the stall margin of the smooth blade is 16.09%. Increasing roughness at the trailing edge further increases the stall margin by 41.02%.

[0038] Table 1

[0039] like Figure 8 As shown, when the blades are roughened, the efficiency decreases near low flow rates and under design flow conditions, while under intermediate flow conditions, it is essentially equivalent to that of smooth blades. The specific efficiency reduction rates are shown in Table 2, ranging from 0.3% to 0.6%.

[0040] Table 3

[0041] After roughening the blade surface in the shock wave-boundary layer interference region of the rotor blade, compared with the smooth prototype blade, the pressure ratio and efficiency are comparable under design conditions. Under non-design conditions, the pressure ratio decreases by a maximum of 1.3%, and the efficiency decreases by 0.3%-0.6%. The stall margin is widened by 41.02% after roughening.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A blade local roughening design method for improving the performance of transonic compressors, characterized in that, include: The roughening addition region is defined based on the interference region of the shock wave and the boundary layer; Set the roughness value for the roughening addition area, and perform initial roughening on the original blade roughening addition area on the blade thickness by removing material; The target blade with local roughening is obtained by smoothing the boundary between the roughened region and the smooth region after initial roughening.

2. The blade local roughening design method for improving the performance of transonic compressors according to claim 1, characterized in that, The shock wave and boundary layer interference regions are used as roughening addition regions.

3. The blade local roughening design method for improving the performance of transonic compressors according to claim 1, characterized in that, Steps to obtain the interference region between the shock wave and the boundary layer: Numerical simulation calculations were performed on the original blade to obtain Mach number cloud maps of the original blade at different height sections; The height range where the shock wave appears is defined as the height of the interference region between the shock wave and the boundary layer. The extent to which the shock wave affects the suction surface of the blade in the Mach number cloud diagram is taken as the length of the interference region between the shock wave and the boundary layer.

4. The blade local roughening design method for improving the performance of transonic compressors according to claim 3, characterized in that, The length range of the roughened area in the blade height direction , ,in, Indicates blade height; This represents the length of the cross section from the blade root at the initial location of the shock wave in the numerical simulation; the location where roughness is added. ,in, This indicates the location where the shock wave strikes the suction surface of a certain section of the blade; This indicates the range of influence of the shock wave on the suction surface of the blade.

5. The blade local roughening design method for improving the performance of transonic compressors according to claim 4, characterized in that, ; This indicates the chord length of the blade.

6. The blade local roughening design method for improving the performance of transonic compressors according to claim 1, characterized in that, The expression for setting the roughness of the roughened region is: In the formula, This indicates the roughness set in the roughening area; This represents a proportional parameter that limits the surface roughness thickness. Indicates the location where roughness is added; Represents a constant; This represents the angular frequency of the trigonometric function used to generate irregular random roughness; This represents the angular frequency of the trigonometric function used to generate irregular random roughness; This represents the phase of the trigonometric function used to generate irregular random roughness.

7. The blade local roughening design method for improving the performance of transonic compressors according to claim 6, characterized in that, The proportional parameter that limits the roughness thickness satisfy Remove the maximum height of the material. , This indicates the local leaf thickness.

8. The blade local roughening design method for improving the performance of transonic compressors according to claim 1, characterized in that, The steps for smoothing the boundary between the initially roughened region and the smoothed region to obtain the locally roughened target blade are as follows: The boundary between the roughened region and the smooth region after initial roughening is smoothed by using a transition function to obtain the target blade with local roughening. The roughness of the target blade for local roughening is: In the formula, This represents the roughness value after smoothing. Represents the transition function; This indicates the roughness set in the roughening area; This indicates the relative position where roughness is added during the transition from a smooth region to a roughened region; This indicates the relative position where roughness is added during the transition from a roughened area to a smooth area; Indicates the location where roughness is added; This indicates the location where the shock wave hits the suction surface of the blade; This indicates the range of influence of the shock wave on the suction surface of the blade; It represents a higher-order small quantity.

9. A blade roughening design method for improving the performance of transonic compressors according to claim 8, characterized in that, The transition function is: In the formula, For transition function, This indicates the relative position where roughness is added to the roughening area.

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