Gas compressor last-stage rotor open type gap leakage flow regulation and control method, structure and application

Abstract

The invention provides a gas compressor last-stage rotor open type gap leakage flow regulation and control method and structure and application, and the method comprises the steps: for a gas compressor last-stage rotor with an open type gap, obtaining blade top time-average flow field parameters, and determining an interference position of a double leakage track and an adjacent blade pressure surface; by taking the interference position as the center, generating local two-dimensional sinusoidal bulges on the pressure surface of the blade top, and stacking the bulges along the spanwise direction; and the molded line of the inner wall of the case near the interference core area is optimized, so that the molded line is further shrunk inwards, and finally, a blade top double-leakage regulation and control scheme for coupling the three-dimensional bulge of the belly of the blade pressure surface and the inner shrunk case modeling is formed. On the premise that the structural complexity is not increased, the blade top pressure / velocity field of the last-stage rotor of the gas compressor is recombined, vortex-vortex interference is restrained to induce expansion of a low axial momentum area, movement of a leakage flow-main flow interface towards the upstream is delayed, and the stable working boundary is widened. The blade top flow capacity can be enhanced, and the method is used for refined design of the blade top of the last-stage gas compressor rotor with the open gap.

Description

Technical Field

[0001] The present invention belongs to the technical field of the design and optimization of aero-engine compressor components, and relates to the technology of controlling the tip clearance flow of a compressor and improving its stability. Specifically, it relates to a method, structure and application for regulating the open tip clearance leakage flow of the last-stage rotor of a compressor, which is used to enhance the axial momentum at the tip of the last-stage rotor blades of the compressor, suppress the expansion of the low-axial-momentum region induced by vortex-vortex interference, delay the upstream movement of the interface between the leakage flow and the mainstream flow, broaden the stable operating boundary of the compressor, and take into account the improvement of efficiency. Background Art

[0002] Modern high-performance turbofan engines are increasingly demanding high thrust-to-weight ratio and low fuel consumption, which has led to an increase in the bypass ratio, a more compact structure of the compression system, and a gradually increasing load. To avoid problems such as rubbing during the cold and hot condition transitions, a certain value of tip clearance must be reserved for the compressor. For the last stage of a compact compressor, the blade height is only 5-10 mm, and the tip clearance is extremely likely to exceed 4% of the relative blade height, forming a so-called open tip clearance. Compared with the conventional tip clearance (usually <3% of the blade height), the leakage flow in the open tip clearance exhibits different dynamic characteristics. Specifically, when the leakage flow detaches from the suction surface, under the action of a strong transverse pressure gradient, it crosses the entire blade pitch and then enters the tip clearance of the adjacent blade, forming double leakage. The dynamic evolution process of double leakage induces strong turbulent pulsation and aerodynamic blockage, which has an adverse impact on the efficiency and stability of the compressor. Therefore, to ensure the efficient and stable operation of the last-stage rotor of the compressor, the primary problem to be solved is the regulation of double leakage at the tip under the open tip clearance.

[0003] When double leakage occurs under the open tip clearance, vortex-vortex interference generates a vortex chain, which invades the leakage core region near the suction surface of the adjacent blade, accelerating the breakup of the local leakage vortex. At this time, the low-axial-momentum region at the tip expands sharply, and the strong blockage induced thereby is the key to triggering the aerodynamic instability of the compressor. Therefore, enhancing the axial momentum at the tip is the fundamental goal of regulating the double leakage flow and stability at the tip.

[0004] To solve the problems of compressor tip clearance leakage and induced aerodynamic instability, a variety of regulation methods have been proposed in the prior art. Common casing treatments (such as Chinese Patent CN102817873B, US Patent US7811049B2, etc.) induce local recirculation flow by introducing structures such as grooves, spiral grooves, and cavities on the inner wall of the casing to enhance the momentum exchange ability in the leakage region, while the tip jet method (such as Chinese Patent Application CN111396357A, etc.) enhances the momentum exchange in the tip leakage region through the jet effect, thereby suppressing the expansion of the low-axial-momentum region. Although casing treatments, tip jets, etc. have great potential in broadening the stable boundary of the compressor, the above-mentioned schemes all have problems to varying degrees, such as complex structures and strong turbulent mixing induced, making it difficult to take into account efficiency.

[0005] In recent years, some studies (such as Chinese patent applications CN107061363A and CN114962329A) have attempted to manipulate the dynamic characteristics of the leakage vortex through blade tip optimization (e.g., local geometric deformation). However, due to the complex interaction mechanism between the leakage vortex and the main flow, its spatiotemporal evolution path is extremely sensitive to the local pressure field, making it difficult to effectively control the complex double leakage behavior through optimization of a single geometric feature. Furthermore, because the double leakage structure induced by the open gap exhibits distinct three-dimensional characteristics and unsteadiness, its evolution mechanism poses even more severe challenges to the design of the coupled casing-blade system.

[0006] In summary, existing technical solutions generally have defects such as reduced efficiency, complex structure or limited control effect when dealing with the problem of double leakage control with open gaps. Therefore, how to efficiently control the double leakage flow at the blade tip of the last-stage rotor of a compressor with open gaps while taking into account the efficiency and stability of the compressor is a technical problem that needs to be urgently solved in the current field of aero-engine compressor design. Summary of the Invention

[0007] (1) Purpose of the invention Starting from the fundamental goal of enhancing the axial momentum of the blade tip of the last-stage rotor of the compressor under open gaps, the present invention proposes a dual leakage flow control method, structure and application that couples the bulge on the pressure surface belly of the blade and the inner contraction casing. By constructing a bulge on the pressure surface belly of the blade tip to control the local pressure / velocity field, the axial momentum of the leakage core area is enhanced, and the leakage flow is more biased toward the suction surface; at the same time, the inner wall of the casing is contracted to further increase the axial momentum of the blade tip, and ultimately delay the upstream movement of the leakage flow-mainstream interface, thereby widening the stability margin. Compared with casing treatment, blade tip jet, etc., the present invention enhances the axial momentum by finely optimizing the blade tip and casing configuration. It not only has a simple structure and a high degree of design freedom, but also can avoid the introduction of external jet effects to induce strong turbulent mixing, thereby taking into account the efficiency and stability margin of the last-stage compressor rotor, and directly supporting the stable and efficient operation of the last-stage compressor rotor.

[0008] (II) Technical solution In order to achieve the purpose of the invention and solve the technical problems, the present invention adopts the following technical solutions: The first object of the present invention is to provide a method for regulating leakage flow in an open gap of a compressor last-stage rotor, which is used to enhance the axial momentum of the blade tip of the compressor last-stage rotor with an open gap, suppress the expansion of the low axial momentum zone induced by vortex-vortex interference, and delay the upstream movement of the leakage flow-mainstream interface, so as to broaden the stable operating boundary of the compressor and improve the overall efficiency. When implemented, the method includes at least the following steps: SS1. Determine the core area of double leakage induction: For the last-stage rotor of a compressor with an open gap, obtain the time-averaged flow field parameters at the blade tip through numerical simulation or experimental measurement, identify the low-axial-momentum core region induced by the vortex-vortex interference of the tip double leakage, and locate the interference position between the double leakage trajectory and the pressure surface of the adjacent blade; SS2. Local two-dimensional convex profiles at different blade heights on the pressure surface: At several different blade height positions near the blade tip, first, with the interference position between the double leakage trajectory and the pressure surface of the adjacent blade as the center, based on the expression Construct sinusoidal two-dimensional convexes respectively, where h is the convex size, A is the convex peak value, x is the flow direction coordinate of the convex and x ∈ x 1, x 2], x 1 and x 2 are the starting and ending positions of the convex flow direction respectively, and the convex peak value A increases uniformly with the blade height, and the convex coverage range x 1, x 2] expands with the blade height; then, project the sinusoidal two-dimensional convexes at each blade height position along the local normal direction onto the pressure surface to complete the local two-dimensional convex profiles of the pressure surface at different blade height positions; SS3. Construct a spanwise three-dimensional convex structure: Parametrically stack the local two-dimensional convexes on the pressure surface at different blade heights in the spanwise direction to construct a three-dimensional convex profile of the blade tip pressure surface, and the three-dimensional convex starts to gradually transition from near 90% blade height to the blade tip, forming a spatial structure that is coordinated and continuous with the main blade profile; SS4. Optimization of the casing inner wall profile in the interference core region: Perform an inwards profile design on the casing inner wall where the double leakage-induced vortex-vortex interference core region is located, increase the axial momentum by reducing the local flow area, the starting position of the inward contraction is upstream of the blade leading edge, the ending position is downstream of the trailing edge, and control the contraction amplitude; SS5. Coupled regulation of the blade tip flow field: Couple the three-dimensional convex on the blade tip pressure surface and the inward-contracted casing, reconstruct the blade tip pressure field and velocity field, delay the formation of the vortex chain and the generation of turbulent pulsation, suppress the expansion of the low-axial-momentum region, thereby delaying the upward movement of the leakage flow-main flow interface, and realizing the regulation of double leakage and stability under the open gap.

[0009] The second object of the present invention is to provide a leakage flow regulation structure for the open gap of the last-stage rotor of a compressor, and the design of this structure is based on the above-mentioned leakage flow regulation method for the open gap of the last-stage rotor of a compressor of the present invention.

[0010] The third object of the present invention is to provide a compressor, including the above-mentioned open-gap leakage flow control structure for the last-stage rotor of the compressor.

[0011] (III) Technical effects Compared with the prior art, the dual-leakage control method, structure and application for the last-stage compressor rotor coupling the belly bulge on the pressure surface of the blade and the inner-contracting casing of the present invention have the following remarkable technical effects: (1) The physical meaning of the control scheme is clear, taking into account both efficiency and stability margin. Starting from the fundamental goal of enhancing the axial momentum at the blade tip for this dual-leakage control, the present invention realizes the recombination of the pressure field / velocity field at the blade tip by coupling the belly bulge on the pressure surface of the blade and the inner-contracting casing, increasing the axial momentum in the core region of the leakage flow. This not only suppresses the generation rate of local turbulent pulsation but also pushes the leakage flow-mainstream interface downstream. Compared with casing treatment, tip jetting, etc., this method can broaden the stability margin of the last-stage compressor rotor while avoiding inducing overly strong turbulent mixing, thereby achieving a dual improvement in efficiency and margin.

[0012] (2) The control structure is simple and has a high degree of design freedom. Based on the parametric expressions, the peak value, spatial position, spanwise stacking method of the belly bulge on the pressure surface, and the profile of the casing inner wall can be quickly adjusted until the optimal control scheme is obtained, which can be directly incorporated into the full three-dimensional design system of the compressor. While ensuring the high-efficiency control effect of dual leakage, it greatly simplifies the fine design process at the blade tip.

[0013] (3) The technology of the present invention is highly targeted, effectively solving the dual-leakage problem faced by the last-stage rotor of the compressor with an open gap (>4% relative blade height), and achieving a good balance between aerodynamic performance optimization and structural simplification. It not only ensures the high efficiency of dual-leakage control but also meets the feasibility requirements of engineering practical applications. The manufacturing process of the belly bulge on the pressure surface and the inner-contracting casing is relatively simple, facilitating implementation in the actual compressor structure. At the same time, the control effect on the flow field is significant, providing direct technical support for the efficient and stable operation of the last-stage rotor of the compressor, and having important engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings, wherein: Figure 1 is a flow chart of the open-gap leakage flow control method for the last-stage rotor of the compressor of the present invention; Figure 2 is a schematic diagram of the open-gap leakage flow control structure for the last-stage rotor of the compressor of the present invention; Figure 3Schematic diagram of the local two-dimensional convex contour of the pressure surface; Figure 4 Profiles of the convex pressure surface at different blade heights near the blade tip, where: (a) is the starting section, (b) is the spanwise section 1, (c) is the spanwise section 2, and (d) is the blade tip section.

[0015] Figure 5 Schematic diagram of the contraction inside the blade tip casing; Figure 6 Comparison diagram of the tip turbulence intensity between the original blade and the coupled and regulated blade, where: (a) is the original blade, and (b) is the coupled and regulated blade. Specific implementation manner

[0016] The object of the present invention is to propose a double-leakage regulation method, structure and application that couple the convexity of the abdominal part of the blade tip pressure surface and the inner contraction casing, and are used to broaden the stable margin of the last-stage rotor of the compressor. To make the purpose, technical solution and advantages of the implementation of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings in the embodiments of the present invention. The described embodiments are part of the embodiments of the present invention, not all of the embodiments, and the described embodiments are exemplary and are intended to explain the present invention and should not be construed as a limitation of the present invention.

[0017] As a specific example, the present invention proposes a regulation scheme for the open-gap leakage flow of the last-stage rotor of the compressor. The relative blade height percentage of the open gap exceeds 4%. Under this gap, the tip leakage flow crosses the entire blade passage and enters the top gap of the adjacent blade, forming a double-leakage phenomenon. Compared with the conventional gap (less than 3% relative blade height), the vortex-vortex interference effect induced by the double leakage under the open gap is more significant, and the impact on the compressor efficiency and stable margin is more serious. The double-leakage regulation method that couples the convexity of the abdominal part of the blade tip pressure surface and the inner contraction casing proposed in the embodiments of the present invention is used to broaden the stable margin of the last-stage rotor of the compressor. Figure 1 The flow chart of the regulation method is given. Figure 2 The schematic diagram of the regulation structure is given. The flow passage gradually contracts along the flow direction, and there are certain gaps between the rotor and stator blade tips and the casing / hub, etc. The key of the present invention lies in the three-dimensional configuration of the convexity of the abdominal part of the rotor blade tip pressure surface and the optimization design of the casing inner wall profile.

[0018] As Figure 1 shown, the main steps and corresponding solutions in the implementation of the open-gap leakage flow regulation method for the last-stage rotor of the compressor proposed in the embodiments of the present invention are as follows: SS1. Determine the core area induced by double leakage: For the last-stage compressor rotor with an open gap, high-precision numerical calculations or experimental measurements are carried out to obtain the time-averaged velocity, time-averaged pressure field, turbulent kinetic energy distribution, and Reynolds stress distribution at the blade tip, etc., and thus identify and determine the low-axial-momentum core region induced by double leakage at the blade tip, especially focusing on the generation of the vortex chain induced by the vortex-vortex interference at the blade tip and its intersection position with the pressure surface of the adjacent blade.

[0019] Preferably, high-precision large-eddy simulation can be used for numerical simulation, and after statistical convergence, no less than ten rotor cycles of transient flow field data are additionally sampled for statistical averaging; for experimental measurement, a PIV system can be used to obtain the three-dimensional velocity field and pressure field in space to accurately capture the double leakage trajectory and the leakage flow vortex system structure characteristics in the blade tip region of the last-stage compressor rotor. In addition, when analyzing the time-averaged flow field parameters at the blade tip, by analyzing the peak value of Reynolds stress or turbulent kinetic energy, the range and position of the vortex-vortex interference core region are identified and located, and the double leakage trajectory is determined through the contour line distribution of the time-averaged velocity / pressure field, and then the intersection position of the double leakage and the pressure surface of the adjacent blade is located.

[0020] SS2. Local two-dimensional convex profiles at different blade heights on the pressure surface: According to the above results analyzed and determined in step SS1, first, at several different blade height positions near the blade tip, with the interference position of the double leakage and the pressure surface of the adjacent blade as the center, parametric modeling of the local convexity on the pressure surface is carried out. The local two-dimensional convex contour adopts a sine-type expression, specifically as follows: In the above formula, h is the size of the local convexity, A is the peak value of the convexity. x is the flow direction coordinate of the convexity and x ∈ x 1, x 2], x 1 and x 2 are the starting and ending positions of the convexity flow direction respectively, and the peak value of the convexity A increases uniformly with the blade height, and the coverage range of the convexity x 1, x 2] expands with the blade height. Figure 3 The local sine-type two-dimensional convex contours under different parameter conditions are compared.

[0021] After that, the sine-type two-dimensional convexities at each blade height position constructed above are projected onto the pressure surface along the local normal direction to complete the two-dimensional convex modeling of the pressure surface at different blade height positions. The method is as follows: Among them, B' is the position of the blade coordinate point after normal superposition of the two-dimensional convexity, B is the position of the original blade coordinate point, is the local unit normal vector of the original blade, and during the projection process, it should be ensured that the pressure surface of the blade maintains geometric continuity and boundary smoothness to avoid forming local geometric mutation regions.

[0022] Next, two-dimensional protrusions on the pressure surface are sequentially generated at different blade heights, such as Figure 4 shown. Several different blade height positions near the blade tip at least include the blade tip positions at 90% blade height, 93% blade height, 96% blade height, and 100% blade height. The two-dimensional protrusions at different blade height positions gradually increase in peak value and gradually expand in coverage range as the blade height increases, where: the 90% blade height section is the position where the two-dimensional protrusion starts to generate ( A =0); at 93% blade height (i.e., "spanwise section 1"), the peak value of the protrusion A takes 20% of the maximum blade thickness, and the position ranges from 25% axial chord length to 65% axial chord length; at 96% blade height (i.e., "spanwise section 2"), the peak value of the protrusion A increases to 30% of the maximum blade thickness, and the distribution position remains unchanged; at the blade tip section, the peak value of the protrusion A still remains at 30% of the maximum blade thickness, but covers from 15% axial chord length to 85% axial chord length.

[0023] SS3. Construct the spanwise three-dimensional protrusion structure: After obtaining the two-dimensional protrusions at the above different blade height positions, parametric stacking is carried out along the spanwise direction to complete the three-dimensional shaping of the blade tip with the protrusion on the abdomen of the pressure surface as the main feature, and the protrusion on the pressure surface of the blade tip gradually transitions from near 90% blade height to the blade tip, forming a spatial structure that is coordinated and continuous with the main blade surface.

[0024] Preferably, the spanwise stacking of the three-dimensional protrusion on the pressure surface of the blade tip is realized by spline curve or polynomial fitting to achieve the transition between sections; by controlling the distribution density of the interpolation nodes, uniform control points are set in the 90% to 93% blade height interval to ensure the smooth transition between the main blade surface and the protrusion region, and more dense control points are set in the 93% to blade tip interval to ensure the spatial continuity of the protrusion shape; after the spanwise stacking is completed, the overall surface curvature is further optimized to ensure that the change in the overall surface curvature is within the allowable range of the main blade surface, avoiding the formation of new additional vortex systems or flow separation regions.

[0025] SS4. Optimization of the inner wall profile of the interference core area casing: After completing the shaping of the protrusion on the pressure surface of the blade tip, the optimization scheme of the inner wall of the casing is as Figure 5As shown. By indenting the casing profile inward, the local flow area is reduced, further increasing the axial momentum in the core region of the tip double leakage vortex-vortex interference. When designing the inward contraction of the casing inner wall profile, a third-order Bezier curve is preferably used to control the shape of the casing inner wall profile and ensure a smooth transition between the contraction region and the original casing profile. Its parametric expression is , where t ∈[0,1], P 0 and P 3 are the starting point and ending point of the curve respectively, P 1 and P 2 are the control points. By adjusting the positions of the control points P 1 and P 2, the shape characteristics of the inward contraction of the casing profile are controlled, and the regulation of the intensity and position of the vortex-vortex interference is achieved. The starting position of the inward contraction of the casing profile is denoted as K 1, which is located at 10% of the tip chord length C upstream of the leading edge of the rotor blade; the ending position is denoted as K 2, which is located at 10% of the tip chord length C downstream of the trailing edge of the rotor blade. A Bezier curve is used to connect K 1 and K 2, and its inward indentation amplitude is 10%-20% of the tip clearance height τ , thus completing the inward contraction design of the casing profile. In addition, the inward contraction amplitude and axial position are adjusted according to the turbulent kinetic energy distribution in the core region of the double leakage-induced vortex-vortex interference, where the region with higher turbulent kinetic energy corresponds to a larger inward contraction amplitude, and the region with lower turbulent kinetic energy corresponds to a smaller inward contraction amplitude, so as to achieve precise regulation of the local flow field.

[0026] SS5. Coupled regulation of the tip flow field: Couple the three-dimensional convex structure on the tip pressure surface and the optimized inward-contracting casing in the interference core region to reconstruct the tip pressure field and velocity field, delay the formation of the vortex chain and the generation of turbulent pulsations, suppress the expansion of the low-axial-momentum region, thereby delaying the upward movement of the leakage flow-main flow interface, and realizing the regulation of double leakage and stability under an open gap.

[0027] To verify the regulation effect of the coupling of the convexity on the abdomen of the blade pressure surface and the inward-contracting casing on the open-gap leakage, Figure 6The turbulence intensity distributions at 98% blade height of the original blade and the coupled-regulated blade are compared. For the original blade, double leakage-induced vortex-vortex interference forms a vortex chain, which is then ingested into the leakage core region of the adjacent blade, accelerating the breakup of the local leakage vortex. At this time, strong momentum exchange induces high-level turbulent pulsations, and the turbulence intensity rises sharply, becoming a direct factor for the decrease in compressor efficiency and the attenuation of the stability margin. When the convexity on the abdominal part of the blade pressure surface and the regulated internal-contraction casing are applied, the axial momentum of the leakage flow core region of the original blade increases, the migration trajectory of the leakage vortex core is closer to the suction surface, the leakage flow-main flow interface is pushed downstream, and the double leakage intensity and the local turbulent pulsation generation rate decrease. It can be seen that the coupled-regulation scheme proposed in the present invention realizes the regulation goal of enhancing the efficiency and expanding the stability of the last-stage compressor by reconstructing the tip pressure field / velocity field.

[0028] Preferably, the implementation process of the coupled regulation is as follows: according to the analysis of the double leakage trajectory and the vortex-vortex interference characteristics, the spatial position relationship between the three-dimensional convex structure on the tip pressure surface and the internal-contraction casing is coordinated and configured to form a complementary strengthening effect in space; the maximum internal-contraction amplitude of the casing is set at the same flow direction position where the peak value of the convexity on the tip pressure surface is located, so that the double leakage flow is simultaneously subjected to the coupled regulation effects from the pressure surface and the casing; at the same time, the overall configuration is aerodynamically optimized and iterated, and the design parameters of the two measures are synergistically adjusted according to the tip flow field until the regulation effect with the lowest turbulence statistical characteristics and the maximum axial momentum is achieved.

[0029] Through the above method, based on the structural synergistic optimization of the convexity on the abdominal part of the tip pressure surface and the internal contraction of the casing, the present invention realizes the effective regulation of the double leakage flow under the open clearance. While improving the tip flow capacity of the last-stage compressor, it takes into account the structural simplification, efficiency improvement and stability margin expansion, providing direct support for the refined design of the last-stage rotor of the compressor.

[0030] Through the above embodiments, the purpose of the present invention is fully and effectively achieved. Those skilled in the art can understand that the present invention includes but is not limited to the content described in the drawings and the above specific embodiments. Although the present invention has been described with respect to the currently considered most practical and preferred embodiments, it should be understood that the present invention is not limited to the disclosed embodiments, and any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims

1. An open-gap leakage flow control method for the last-stage rotor of a compressor, characterized in that Including: SS1. For the last-stage compressor rotor with an open gap, obtain the time-averaged flow field parameters at the blade tip through numerical simulation or experimental measurement, identify the low-axial-momentum core region of the vortex-vortex interference induced by double tip leakage, and locate the interference position between the double leakage trajectory and the pressure surface of the adjacent blade; SS2. At several different blade heights near the blade tip, centered on the interference position, a sinusoidal two-dimensional protrusion is constructed based on the expression where h is the protrusion size, A is the protrusion peak value, x is the flow direction coordinate of the protrusion and x ∈ x 1, x 2], x 1 and x 2 are the starting and ending positions of the protrusion flow direction respectively, and the protrusion peak value A increases uniformly with the blade height. The coverage range of the protrusion x 1, x 2] expands with the blade height; then, the sinusoidal two-dimensional protrusions at each blade height are projected onto the pressure surface to complete the local two-dimensional protrusion modeling of the pressure surface; SS3. Parametrically stack the local two-dimensional protrusions on the pressure surface at different blade heights in the spanwise direction to construct a three-dimensional protrusion shape on the blade tip pressure surface, and the three-dimensional protrusion gradually transitions from near 90% blade height to the blade tip, forming a smooth and continuous spatial structure with the main blade surface; SS4. Conduct a profile shrinkage design on the inner wall of the casing where the core region of the double leakage-induced vortex-vortex interference is located, increase the axial momentum by reducing the local flow area, with the starting position of the shrinkage upstream of the blade leading edge and the ending position downstream of the trailing edge, and control the shrinkage amplitude; SS5. Couple the three-dimensional protrusion on the blade tip pressure surface with the inner-shrunk casing, reconstruct the pressure field and velocity field at the blade tip, delay the formation of the vortex chain and the generation of turbulent pulsations, suppress the expansion of the low-axial-momentum region, thereby delaying the upward movement of the leakage flow-main flow interface, and realizing the regulation of double leakage and stability under the open gap; 2. The method for regulating the open clearance leakage flow of the last-stage rotor of a compressor according to claim 1, wherein In the above step SS1, the numerical simulation is carried out using large-eddy simulation, and after statistical convergence, at least ten rotor cycle transient flow field data are additionally sampled for statistical averaging; the experimental measurement uses PIV to obtain the velocity field and pressure field information to accurately capture the double leakage trajectory and the vortex system structure characteristics in the blade tip region.

3. The method for controlling the open gap leakage flow of the compressor final stage rotor according to claim 1, characterized in that: In the above step SS1, the time-averaged flow field parameters at the blade tip at least include the time-averaged velocity field, time-averaged pressure field, turbulent kinetic energy distribution, and Reynolds stress distribution. By analyzing the peak value of the Reynolds stress or turbulent kinetic energy, identify and locate the range and position of the vortex-vortex interference core region. Determine the double leakage trajectory through the contour distribution of the time-averaged velocity / pressure field, and then locate the intersection position of the double leakage and the pressure surface of the adjacent blade.

4. The method for regulating the open clearance leakage flow of the last-stage rotor of a compressor according to claim 1, characterized in that In the above step SS2, the different blade height positions near the blade top include at least the blade top positions of 90% blade height, 93% blade height, 96% blade height and 100% blade height, wherein the 90% blade height position is the spanwise starting position of the two-dimensional bulge, and its bulge peak is A is 0; at 93% leaf height, A Take the maximum thickness of the blade t max At 20% of the blade height, the convexity covers 25% to 65% of the axial chord length; at 96% of the blade height, A Pick t max 30% of the blade tip, and the convexity covers 25% to 65% of the axial chord length; at the blade tip, A Pick t max The protrusion covers 15% to 85% of the axial chord length.

5. The method for regulating the open gap leakage flow of the last stage rotor of a compressor according to claim 1, characterized in that: In the above step SS2, the sinusoidal two-dimensional convexity is projected onto the pressure surface along the local normal direction, and the vector addition principle is used. Perform coordinate transformation, where B' is the blade coordinate point position after normal superposition of two-dimensional convexity, B is the original blade coordinate point position, h is the size of the local bulge, n 0 is the local unit normal vector of the original blade. During the projection process, the blade pressure surface should be guaranteed to maintain geometric continuity and boundary smoothness.

6. The method for regulating the open gap leakage flow of the last stage rotor of a compressor according to claim 1, characterized in that: In the above step SS3, the spanwise stacking is realized by spline curve or polynomial fitting to achieve the transition between sections; uniform control points are set in the blade height interval from 90% to 93% to ensure the smooth transition between the main surface and the protrusion region, and more fine control points are set in the interval from 93% to the blade tip to ensure the spatial continuity of the protrusion shape; after the spanwise stacking is completed, further optimize the overall surface curvature.

7. The method for regulating the open clearance leakage flow of the last stage rotor of a compressor according to claim 1, wherein In the above step SS4, the third-order Bessel curve is used to control the shape of the inner wall profile of the casing, ensuring a smooth transition between the contracted area and the original casing profile; the starting position of the contraction is set near 10% of the blade tip chord length upstream of the leading edge of the blade, and the ending position is set near 10% of the blade tip chord length downstream of the trailing edge of the blade. The maximum contraction amplitude is controlled within 10%-20% of the blade tip clearance height τ of the blade tip clearance height 8. The method for regulating the open clearance leakage flow of the last-stage rotor of a compressor according to claim 1, characterized in that In the above step SS5, the implementation process of the coupled regulation is as follows: According to the analysis of the double leakage trajectory and vortex-vortex interference characteristics, coordinate and configure the spatial position relationship between the three-dimensional protrusion structure on the blade tip pressure surface and the inner-shrunk casing, so that the two form a complementary and strengthening effect in space; set the maximum inner shrinkage amplitude of the casing at the same flow direction position where the peak value of the protrusion on the blade tip pressure surface is located, so that the double leakage flow is simultaneously subjected to the coupled regulation effects from the pressure surface and the casing; at the same time, conduct aerodynamic optimization iteration on the overall configuration, and adjust the design parameters of the two measures according to the blade tip flow field until the regulation effect with the lowest turbulent statistical characteristics and the largest axial momentum is achieved.

9. An open-gap leakage flow control structure for the last-stage rotor of a compressor, characterized in that The design of this structure is based on the method for regulating the open-gap leakage flow of the last-stage compressor rotor described in any one of claims 1 to 8.

10. A compressor, characterized in that, Including the structure for regulating the open-gap leakage flow of the last-stage compressor rotor described in claim 9.

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