A method for optimizing the natural frequency of a supercharger turbine and a supercharger turbine

Abstract

The present invention discloses a method for optimizing the natural frequency of a supercharger turbine and a supercharger turbine, which relates to the technical field of turbochargers, and includes the following steps: the supercharger turbine before optimization includes a wheel disc, a rotor shaft and a first blade, and includes the following steps: determining the bevel line of the first trailing edge at the axial outlet position for cutting the first blade, the starting end point of the bevel is at a position offset α inward along the axial direction at the tip position of the maximum diameter of the contour line of the first trailing edge, the angle of the bevel line relative to the radial plane is β, and the ending end point of the bevel is at the chamfer position of the root of the first blade; the outer part of the first blade at the bevel line is cut off to form a second blade, and the rotor shaft, the wheel disc and the second blade are combined to form the optimized supercharger turbine. The method provided by the present invention solves the technical problem that the prior art mainly considers improving the vibration resistance of turbine blades from the perspective of the excitation source, and the technical means are relatively complex and the improvement cost is high.

Description

Technical Field

[0001] The present invention relates to the technical field of turbochargers, and in particular to a method for optimizing the natural frequency of a turbocharger turbine and a turbocharger turbine. Background Art

[0002] With the improvement of engine performance, the failure of key engine components has become increasingly prominent. As one of the core parts of the engine, the failure of supercharger components will have a serious impact on the engine's functions and performance. Most supercharger failures are caused by low-cycle fatigue fracture and high-cycle fatigue fracture of the blades. High-cycle fatigue fracture is also known as stress fatigue damage, which is mainly caused by fatigue fracture caused by blade resonance. The main reason for the resonance is that the natural frequency of the blade is equal to or an integer multiple of the excitation frequency in the working environment, which causes the blade to produce a large amplitude vibration response. After a certain number of stress cycles, fatigue cracks appear on the blade until it breaks.

[0003] The excitation source of the turbine blades is mainly caused by uneven airflow in front of the turbine blades. The reasons for the formation of periodic excitation force on the turbine blades are relatively complex, mainly related to factors such as uneven ignition of the engine cylinders, exhaust manifold connection method, volute inlet flow channel form, volute nozzle ring blades, etc. Improving the high-cycle fatigue fracture of the turbine from the perspective of the excitation source is costly and takes a long time.

[0004] In order to avoid the risk of blade resonance in the supercharger turbine, the commonly used improvement measures include increasing the blade vibration natural frequency, reducing the blade exciting force and improving the blade vibration resistance. In the prior art, the blade exciting force is mainly reduced from the perspective of the excitation source, and its technical means are relatively complex and the improvement cost is high. In view of this, it is necessary to propose a method for optimizing the natural frequency of a supercharger turbine and a supercharger turbine to solve or at least alleviate some of the above defects. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for optimizing the natural frequency of a supercharger turbine and a supercharger turbine, aiming to solve the technical problem that the prior art mainly considers reducing the blade exciting force from the perspective of the exciting source, and the technical means are relatively complex and the improvement cost is high.

[0006] To achieve the above-mentioned purpose, the present invention provides a method for optimizing the natural frequency of a supercharger turbine, comprising the steps of: the supercharger turbine before optimization comprises a wheel disc, a rotor shaft and a first blade, the rotor shaft and the wheel disc are coaxially arranged, the first blade is arranged on the wheel disc and is spirally arranged, and a turbine airflow channel is formed between two adjacent first blades and the wheel disc, comprising the steps of: determining a bevel line of a first trailing edge at an axial air outlet position for cutting the first blade, the bevel line having a bevel starting endpoint and a bevel ending endpoint, the bevel starting endpoint is at a position where the tip position of the maximum diameter of the contour line of the first trailing edge is offset inwardly along the axial direction by α, the angle of the bevel line relative to the radial plane is β, and the bevel ending endpoint is at the chamfer position of the root of the first blade; the outer part of the first blade at the bevel line is cut off to form a second blade, and the rotor shaft, the wheel disc and the second blade are combined to form the optimized supercharger turbine.

[0007] Furthermore, the wheel disc includes a central hub and a wheel back, the central hub is arranged above the wheel back, the rotor shaft, the wheel back and the central hub are coaxially arranged, the first blade is arranged between the central hub and the wheel back, the turbine air flow channel has a radial air inlet arranged close to the wheel back and an axial air outlet arranged close to the first trailing edge of the first blade, and eleven groups of first blades are evenly spaced along the circumferential direction.

[0008] Further, the value range of α is 1.0 to 2.0 mm, and the value range of β is 10° to 11°.

[0009] Further, the value of α is 1.5 mm, and the value of β is 10.8°.

[0010] Furthermore, the thickness of the first blade gradually increases along the radial direction pointing toward the central axis.

[0011] Furthermore, the chamfer radius of the blade root is gradually reduced in the direction from the radial air inlet toward the axial air outlet.

[0012] Further, the inlet geometric angle of the first blade is 0°, and the outlet geometric angle of the first blade is 63.8°.

[0013] Furthermore, the step of “cutting off the side of the oblique line close to the outlet to form a new supercharger turbine” specifically includes:

[0014] Clamp and fix the two ends of the rotor shaft of the turbocharger turbine before optimization through a dividing head;

[0015] The first blade is ground based on the bevel line by using an external cylindrical grinder, and the outer part of the bevel line is ground to form a second blade. The second blade, the rotor shaft, the wheel disc and the second blade are combined to form an optimized supercharger turbine.

[0016] Furthermore, the model tangent is determined based on the simulation optimization of the turbocharger turbine model.

[0017] The simulation model is cut out based on the model tangent, an optimized design three-dimensional diagram is obtained according to the simulation model after the cut out, and the blank of the optimized supercharger turbine is cast based on the optimized design three-dimensional diagram.

[0018] The present invention also provides a supercharger turbine, which is manufactured by using the above method for optimizing the natural frequency of the supercharger turbine.

[0019] Compared with the prior art, the method for optimizing the natural frequency of a supercharger turbine provided by the present invention has the following beneficial effects:

[0020] The method for optimizing the natural frequency of a supercharger turbine provided by the present invention transforms the first blade of the supercharger turbine before optimization into the structural form of the second blade, thereby increasing the natural vibration frequency of the turbine blade, and making the natural vibration frequency of the turbine blade avoid the frequency of the exciting force, so that the turbine blade does not resonate, and the occurrence of turbine blade failure is reduced, thereby solving the technical problem that the prior art mainly considers improving the vibration resistance of the turbine blade from the perspective of the exciting source, and the technical means are relatively complex and the improvement cost is high; when optimizing, the bevel starting end point of cutting the first trailing edge and the slope of the bevel line are determined, and the bevel ending end point is determined to be located at the chamfer position of the blade root of the first blade, and the weak part of the first trailing edge of the existing supercharger turbine before optimization is cut off to form an optimized supercharger turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram of the structure of an optimized front supercharger turbine in the prior art;

[0023] Figure 2 1 is a flow chart of a method for optimizing the natural frequency of a supercharger turbine according to an embodiment of the present invention;

[0024] Figure 3 is a schematic diagram of an optimization process in one embodiment of the present invention;

[0025] Figure 4 is a schematic structural diagram of an optimized supercharger turbine in one embodiment of the present invention;

[0026] Figure 5 is a schematic structural diagram of an optimized supercharger turbine in one embodiment of the present invention;

[0027] Figure 6 is a schematic structural diagram of an optimized supercharger turbine in one embodiment of the present invention;

[0028] Figure 7 It is a test flow diagram of the first-order vibration natural frequency;

[0029] Figure 8 It is a test schematic diagram of the first-order vibration natural frequency of the turbocharger turbine before optimization;

[0030] Fig. 9 It is a test schematic diagram of the first-order vibration natural frequency of the optimized supercharger turbine.

[0031] Legend:

[0032] 100, supercharger turbine; 10, wheel back; 20, center hub; 30, second blade; 31, second trailing edge line; 311, trailing edge starting end point; 312, trailing edge ending end point; 313, blade root chamfer; 40, turbine airflow channel; 501, first trailing edge; 502, tip.

[0033] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0034] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0037] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0038] Please refer to the attached Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 The present invention provides a method for optimizing the natural frequency of a supercharger turbine. The supercharger turbine before optimization comprises a wheel disc, a rotor shaft and a first blade. The rotor shaft is coaxially arranged with the wheel disc. The first blade is arranged on the wheel disc and is spirally arranged. A turbine airflow channel is formed between two adjacent first blades and the wheel disc. The method comprises the following steps: determining a bevel line of a first trailing edge at a turbine outlet position for cutting the first blade, the bevel line having a bevel starting end point and a bevel ending end point. The bevel starting end point is at a position offset α inwardly from a tip 502 of a maximum diameter of a contour line of the first trailing edge in an axial direction. The angle of the bevel line relative to a radial plane is β. The bevel ending end point is at a chamfer position of a blade root of the first blade. Cutting off a side of the bevel line toward an axial air outlet forms an optimized supercharger turbine.

[0039] The method for optimizing the natural frequency of a supercharger turbine provided by the present invention improves the natural frequency of vibration of the first blade by modifying the supercharger turbine before optimization, so that the natural frequency of vibration of the first blade of the turbine avoids the frequency of the exciting force, thereby preventing the first blade from resonating and reducing the occurrence of first blade failure, thereby solving the technical problem that the exciting force of the first blade is mainly reduced from the perspective of the exciting source in the prior art, and the technical means are relatively complex and the improvement cost is relatively high; when optimizing, the starting endpoint of the bevel cutting of the first trailing edge and the slope of the bevel cutting line are determined, and the ending endpoint of the bevel cutting is determined to be located at the chamfer position of the blade root of the first blade, and the weak part of the first trailing edge of the existing supercharger turbine before optimization is cut off to form an optimized supercharger turbine.

[0040] Furthermore, the wheel disc includes a central hub and a wheel back, the central hub is arranged above the wheel back, the rotor shaft, the wheel back and the central hub are coaxially arranged, the first blade is arranged between the central hub and the wheel back, the turbine airflow channel has a radial air inlet arranged close to the wheel back and an axial air outlet arranged close to the first trailing edge of the first blade, and eleven groups of the first blades are evenly spaced along the circumferential direction.

[0041] Further, the value range of α is 1.0 to 2.0 mm, and the value range of β is 10° to 11°.

[0042] Further, the value of α is 1.5 mm, and the value of β is 10.8°.

[0043] Furthermore, the thickness of the first blade gradually increases in the radial direction pointing to the central axis. In the present invention, the radial outer edge of the first blade gradually increases in thickness and extends to the blade root, and the maximum thickness of the radial outer edge of the first blade is 0.6 mm.

[0044] Furthermore, the blade root chamfer radius is gradually reduced in the direction from the radial air inlet to the axial air outlet. In the present invention, the inlet blade root chamfer radius of the first blade is 1.8 mm, the outlet blade root chamfer radius of the first blade is 1.2 mm, and the blade root chamfer is a variable chamfer design.

[0045] Furthermore, the effective blade height of the first blade is 9.8 mm.

[0046] Furthermore, an inlet geometric angle of the first blade is 0°, and an outlet geometric angle of the first blade is 63.8°.

[0047] Furthermore, the step of “cutting off the side of the oblique line close to the outlet to form a new supercharger turbine” specifically includes:

[0048] Clamp and fix the two ends of the rotor shaft of the turbocharger turbine before optimization through a dividing head;

[0049] Grinding is performed on a cylindrical grinder based on the bevel line, and the portion of the bevel line close to the outlet is ground.

[0050] Furthermore, the model tangent is determined based on the simulation optimization of the turbocharger turbine model.

[0051] The simulation model is cut out based on the model tangent, an optimized design three-dimensional diagram is obtained according to the simulation model after the cut out, and the blank of the optimized supercharger turbine is cast based on the optimized design three-dimensional diagram.

[0052] The present invention also provides a supercharger turbine, which is manufactured by using the above method for optimizing the natural frequency of the supercharger turbine.

[0053] Please refer to Figure 4 , Figure 5 as well as Figure 6 It can be understood that the supercharger turbine 100 of the present invention is a post-supercharger turbine, including a wheel back 10, a central hub 20, a second blade 30 and a rotor shaft, wherein the central hub 20 is arranged on one side of the wheel back 10, the rotor shaft, the wheel back 10 and the central hub 20 are coaxially arranged and fixedly connected, the second blade 30 is arranged between the central hub 20 and the wheel back 10, and a turbine air flow channel 40 is formed between the central hub 20, the wheel back 10 and two adjacent second blades 30, the turbine air flow channel 40 has a radial air inlet arranged near the wheel back 10 and an axial air outlet arranged near the first trailing edge 501 of the second blade 30, the angle between the second trailing edge line 31 of the second blade 30 and the radial plane is β, and the value range of β is 10° to 11°.

[0054] Further, the eleven groups of the second blades 30 are evenly spaced and arranged along the circumferential direction.

[0055] Furthermore, the second trailing edge line 31 (i.e., the bevel line) has a trailing edge starting endpoint 311 (i.e., the bevel starting endpoint) and a trailing edge terminating endpoint 312 (i.e., the bevel ending endpoint), the trailing edge starting endpoint 311 is located at the tip position of the maximum diameter of the contour line of the second trailing edge, and the trailing edge terminating endpoint 312 is located at the blade root chamfer 313 of the second blade 30.

[0056] Furthermore, the wheel back 10 is a star-shaped disk back structure, and the second blades 30 are arranged on the outer convex lugs of the wheel back 10 .

[0057] Further, the value of β is 10.8°.

[0058] Furthermore, the thickness of the second blade 30 gradually increases in the radial direction pointing to the central axis of the second blade 30. The maximum thickness of the radial outer edge of the second blade 30 is 0.6 mm.

[0059] Furthermore, the radius of the blade root chamfer 313 is gradually reduced in the direction from the radial air inlet to the axial air outlet. The radius of the inlet blade root chamfer 313 of the second blade 30 is 1.8 mm, and the radius of the outlet blade root chamfer 313 of the second blade 30 is 1.2 mm. The blade root chamfer 313 is a variable chamfer design.

[0060] Furthermore, the effective blade height of the second blade 30 is 9.8 mm.

[0061] Furthermore, the rotor shaft is inserted into the central hub 20 and is interference fit with the central hub 20 .

[0062] Specifically, the wheel back 10 is a star-shaped disk back structure, the center hub 20, the wheel back 10 and one end of the rotor shaft are connected by electron beam welding, the other end of the rotor shaft passes through the compressor impeller shaft hole, and the impeller is inserted into the groove on the turbine shaft with an interference fit, and the impeller is fixed by a locking nut to prevent the impeller from moving on the turbine shaft.

[0063] Please refer again Figure 7 , Figure 8 as well as Fig. 9 , a simulation method is used for experimental verification, including the following steps: step S1, extracting a three-dimensional simulation model of the turbine; step S2, meshing the turbine rotor; step S3, performing FEA solution on the turbine rotor; and step S4, performing high cycle fatigue experimental verification.

[0064] The structural strength and vibration verification analysis of the turbocharger turbine before optimization is performed by using a simulation method. Specifically, the method comprises the following steps: step S11, extracting a three-dimensional simulation model of the turbine before optimization; step S12, using Hypermesh pre-processing software to generate high-quality second-order tetrahedral mesh units; step S13, setting material parameters, loads, and constraints for FEA analysis, and extracting FEA results, wherein the first-order natural frequency is 11945 Hz, and the cloud map is shown in FIG. Figure 8 As shown; Step S14, the turbocharger turbine is subjected to high cycle fatigue test verification before optimization, and three tests are carried out in succession, each for 100 hours, and a blade falling failure occurs at the turbine outlet tip.

[0065] The structural strength and vibration verification analysis of the optimized turbocharger turbine is performed by using a simulation method. Specifically, the method comprises the following steps: step S21, extracting a three-dimensional simulation model of the optimized turbine; step S22, generating high-quality second-order tetrahedral mesh units by using Hypermesh pre-processing software; step S23, setting material parameters, loads, and constraints for FEA analysis, and extracting FEA results, wherein the first-order natural frequency is 13061 Hz, and the cloud map is shown in FIG. Fig. 9 As shown; Step S24, the turbocharger turbine is subjected to high cycle fatigue test verification before optimization, and three tests are carried out in succession, each for 100 hours, and a blade falling failure occurs at the turbine outlet tip.

[0066] The optimized supercharger turbine provided by the present invention has a turbine natural frequency that is increased by 10.18% after optimization compared with that before optimization; the turbine has better performance in mechanical stress and vibration frequency under the effects of centrifugal, temperature and aerodynamic loads; the turbine natural frequency of vibration can be increased, the turbine's anti-vibration ability can be enhanced, and the risk of high-cycle fatigue fracture can be avoided; and the overall reliability of the supercharger can be improved.

[0067] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for optimizing the natural frequency of a supercharger turbine, wherein the supercharger turbine before optimization comprises a wheel disc, a rotor shaft and a first blade, wherein the rotor shaft and the wheel disc are coaxially arranged, the first blade is arranged on the wheel disc and is spirally arranged, and a turbine airflow channel is formed between two adjacent first blades and the wheel disc, characterized in that: Includes steps: Determine a bevel line for cutting a first trailing edge at an axial air outlet position of the first blade, the bevel line having a bevel start endpoint and a bevel end endpoint, the bevel start endpoint is located at a position offset α inwardly along the axial direction from a sharp point position of a maximum diameter of a contour line of the first trailing edge, the angle of the bevel line relative to a radial plane is β, and the bevel end endpoint is located at a chamfer position of a blade root of the first blade; The outer portion of the first blade located at the oblique cutting line is cut off to form a second blade, and the rotor shaft, the wheel disk and the second blade are combined to form an optimized supercharger turbine.

2. The method for optimizing the natural frequency of a supercharger turbine according to claim 1, characterized in that: The wheel disc comprises a central hub and a wheel back, wherein the central hub is arranged above the wheel back, the rotor shaft, the wheel back and the central hub are coaxially arranged, the first blade is arranged between the central hub and the wheel back, and the turbine airflow channel comprises a radial air inlet arranged close to the wheel back and an axial air outlet arranged close to a first trailing edge of the first blade, The eleven groups of the first blades are evenly spaced apart along the circumferential direction.

3. The method for optimizing the natural frequency of a supercharger turbine according to claim 1, characterized in that: The value range of α is 1.0 to 2.0 mm, and the value range of β is 10° to 11°.

4. The method for optimizing the natural frequency of a supercharger turbine according to claim 3, characterized in that: The value of α is 1.5 mm, and the value of β is 10.8°.

5. The method for optimizing the natural frequency of a supercharger turbine according to claim 1, characterized in that: The thickness of the first blade gradually increases along a radial direction pointing to the central axis.

6. The method for optimizing the natural frequency of a supercharger turbine according to claim 1, characterized in that: The chamfer radius of the blade root is gradually reduced in the direction from the radial air inlet to the axial air outlet.

7. The method for optimizing the natural frequency of a supercharger turbine according to claim 1, characterized in that: The inlet geometric angle of the first blade is 0°, and the outlet geometric angle of the first blade is 63.8°.

8. The method for optimizing the natural frequency of a supercharger turbine according to claim 1, characterized in that: The step of "cutting off the side of the oblique line close to the outlet to form a new supercharger turbine" specifically includes: Clamp and fix the two ends of the rotor shaft of the turbocharger turbine before optimization through a dividing head; The first blade is ground based on the bevel line by using an external cylindrical grinder, and the outer part of the bevel line is ground to form a second blade. The second blade, the rotor shaft, the wheel disc and the second blade are combined to form an optimized supercharger turbine.

9. The method for optimizing the natural frequency of a supercharger turbine according to claim 1, characterized in that: Based on the simulation optimization of the front turbocharger turbine model, the model tangent is determined. The simulation model is cut out based on the model tangent, an optimized design three-dimensional diagram is obtained according to the simulation model after the cut out, and the blank of the optimized supercharger turbine is cast based on the optimized design three-dimensional diagram.

10. A supercharger turbine, characterized in that: The method for optimizing the natural frequency of a supercharger turbine according to any one of claims 1 to 9 is used for manufacturing the supercharger turbine.

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