Turbocharger volute assembly and design method thereof

Abstract

The invention relates to a turbocharger volute assembly and a design method thereof. The volute comprises a volute, a plurality of guide vanes are distributed in an outlet diffusion section of the volute in the circumferential direction, and the guide vanes are used for guiding the gas flow direction to be converted into the axial direction from the circumferential direction; the tangential angle of the inlet direction of the guide vane is configured in the mode that the ratio of the axial component to the circumferential component of airflow at the inlet in the flowing direction of the guide vane is kept consistent with the ratio of the axial component to the circumferential component of the speed of gas entering the guide vane. The included angle between the outlet direction of the guide vanes and the axis of the turbine is 0 degree. The angle of exhausted gas is adjusted through the outlet guide vanes, and the circumferential speed energy of turbine exhaust is fully utilized, so that the axial speed of the gas is increased, the circumferential speed is reduced, and the vortex end efficiency of a design area of a low-speed area is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of turbochargers, and in particular to a turbocharger volute assembly and a design method thereof. Background Art

[0002] A turbocharger is a device that converts the energy of the engine's exhaust pulses into work energy for the turbine at the turbine end. After gaining kinetic energy, the turbine drives the coaxial compressor impeller to rotate, causing the compressor impeller to perform work on the intake air, giving the intake air kinetic energy and increasing the density of the air entering the engine. With increasingly stringent engine emission standards, the thermal efficiency requirements for turbochargers are constantly increasing, especially the thermal efficiency of the turbine end. This improvement has a direct impact on the overall thermal efficiency of the turbocharger.

[0003] In practical applications, engine operating conditions are complex and highly variable, and each operating condition has varying impacts on supercharger performance. Therefore, the efficiency of the turbocharger's turbine end under actual operating conditions has become a key focus of research and optimization. Within the overall process of improving turbine end efficiency, effectively improving turbine end efficiency at the design point in the low-speed region has become a hot topic and a focal point of current research.

[0004] The exhaust gas discharged by the engine first enters the volute flow channel, then drives the turbine blades to do work. After completing the energy conversion, the exhaust gas enters the diffuser through the turbine outlet. The gas passing through the turbine has a certain axial velocity and circumferential velocity. After entering the diffuser, the gas continues to move forward at a certain rotational speed and is eventually discharged into the atmosphere. However, in this process, the circumferential velocity energy of the gas is not fully utilized, resulting in energy loss. The relative velocity of the gas discharged from the turbine is related to the turbine outlet angle, and the actual speed of the gas is determined by this relative velocity and the turbine speed. Therefore, it is urgent to improve the turbine end efficiency in the low-speed design area to reduce energy loss. Summary of the Invention

[0005] To this end, the present invention provides a turbocharger volute assembly and a design method thereof, which adjusts the angle of the exhaust gas through the outlet guide vanes, fully utilizes the circumferential velocity energy of the turbine exhaust, thereby increasing the axial velocity of the gas and reducing the circumferential velocity, thereby effectively improving the turbine end efficiency in the low-speed design area.

[0006] To solve the above technical problems, the present invention provides a turbocharger volute assembly, comprising a volute, wherein a plurality of guide vanes are distributed circumferentially inside an outlet diffuser section of the volute, and the plurality of guide vanes are used to guide the gas flow direction from the circumferential direction to the axial direction; The tangential angle of the guide vane in the inlet direction is configured such that the ratio of the axial component to the circumferential component of the airflow along the flow direction of the guide vane at the inlet is consistent with the ratio of the axial component to the circumferential component of the velocity of the gas entering the guide vane; and the angle between the outlet direction of the guide vane and the turbine axis is 0°.

[0007] In one embodiment of the present invention, the trajectory of the guide vane is configured to satisfy an elliptic curve equation.

[0008] In one embodiment of the present invention, the axial length of the guide vane is 0.8 to 2 times the diameter of the turbine outlet, and the width of the guide vane is 0.08 to 0.15 times the diameter of the turbine outlet.

[0009] The present invention also provides a method for designing a turbocharger volute assembly, comprising: The velocity of the gas flowing out of the turbine and into the diffuser under the design working conditions is obtained through simulation calculation, and the axial component and circumferential component of the gas velocity are obtained; According to the axial component and the circumferential component of the gas velocity, a ratio tanθ2 of the axial component to the circumferential component of the gas velocity entering the guide vane is obtained; The tangential angle θ1 of the guide vane inlet direction is designed to make the ratio of the axial component to the circumferential component of the airflow along the flow direction of the guide vane at the inlet, tanθ1, equal to tanθ2; The trajectory of the guide vane is configured as an elliptical curve, and the standard equation of the elliptical curve is: , Where h and k are the coordinates of the ellipse center, 2a is the minor axis of the ellipse, and 2b is the major axis of the ellipse. The major axis of the ellipse is parallel to the Y axis, and the minor axis is parallel to the X axis. x∈(-a, 0), y∈(-b, 0). a and b satisfy 0.8D≤b≤2D, a<b, and D is the turbine outlet diameter. The tangent slope dy / dx at the starting position of the guide vane, i.e., at the inlet direction, is configured to satisfy the following relationship: dy / dx=tanθ1, and the angle between the outlet direction of the guide vane and the turbine axis is configured to be 0°; According to the relationship between the standard equation of the elliptic curve and the slope of the tangent line at the starting position of the guide vane, the trajectory line of the guide vane is obtained; According to the trajectory of the guide vane, the efficiency value of the turbine end operating point is obtained by simulation calculation; By adjusting the values of a and b and performing simulation calculations within a limited range, the turbine end efficiency values under different elliptical curve trajectories are obtained, and the trajectory line with the highest turbine end efficiency value is selected as the optimal trajectory line of the guide vane.

[0010] In one embodiment of the present invention, the width of the guide vane is 0.08 to 0.15 times the diameter of the turbine outlet.

[0011] The above technical solution of the present invention has the following advantages over the prior art: The turbocharger volute assembly and design method described in the present invention arranges multiple guide vanes on the inner wall of the volute outlet diffuser section along the circumference of the turbine axis, so that the gas flow direction can be efficiently converted from circumferential to axial. The tangential angle of the guide vane's inlet direction is precisely configured based on the ratio of the axial component to the circumferential component of the actual airflow velocity, ensuring that the gas flow state at the guide vane inlet is highly matched to the actual operating conditions, thereby reducing the loss of gas flow energy. At the same time, the angle between the guide vane outlet direction and the turbine axis is 0°, allowing the gas to enter the diffuser in the optimal axial state, effectively increasing the axial velocity and reducing the circumferential velocity.

[0012] The guide vanes of the present invention are designed with elliptical curve trajectories, and the efficiency under different trajectory parameters is optimized by simulation calculations to ensure that the turbine end efficiency is maximized under the design working conditions in the low-speed area. By reasonably limiting the structural parameters such as the axial length and width of the guide vanes, it can adapt to different gas distribution characteristics and take into account the efficiency requirements under other working conditions. This design not only improves the energy utilization rate in the turbine end area, but also effectively improves the overall thermal efficiency of the turbocharger, meeting the current development needs of high-efficiency and low-emission engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0014] Figure 1 Schematic diagram of the structure of the turbocharger volute assembly in Example 1 of the present invention.

[0015] Figure 2 It is a front cross-sectional structural schematic diagram of the turbocharger volute assembly in Example 1 of the present invention.

[0016] Figure 3 It is a schematic top view of the structure of the turbocharger volute assembly in Example 1 of the present invention.

[0017] Figure 4 Schematic diagram of the trajectory of the guide vane in Example 2 of the present invention.

[0018] Figure 5 : is the outlet circumferential velocity distribution vector diagram without guide vanes in Example 2 of the present invention.

[0019] Figure 6This is a vector diagram of the outlet circumferential velocity distribution after guide vanes are added in Example 2 of the present invention. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0021] In the present invention, if directions (up, down, left, right, front and back) are described, it is only for the convenience of describing the technical solution of the present invention, and does not indicate or imply that the technical features referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it cannot be understood as a limitation of the present invention.

[0022] In the present invention, "several" means one or more, "multiple" means more than two, "greater than," "less than," "exceeds," etc. are understood to exclude the number itself; "above," "below," "within," etc. are understood to include the number itself. In the description of the present invention, the use of "first" or "second" is solely for the purpose of distinguishing technical features and is not to be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0023] In the present invention, unless otherwise expressly defined, terms such as "disposed," "installed," and "connected" should be interpreted broadly. For example, they may refer to direct connection or indirect connection through an intermediate medium; fixed connection or detachable connection or integral molding; mechanical connection or electrical connection or mutual communication; and internal connection between two components or interaction between two components. Those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0024] Example 1 Reference Figures 1 to 3 As shown, this embodiment provides a turbocharger volute assembly, including a volute, a volute spiral flow channel provided on the volute, a central axis provided in a central rotation area, the volute spiral flow channel being used to guide exhaust gas discharged from the engine to flow into the turbine along a predetermined path; a plurality of guide vanes are distributed circumferentially inside (on the inner wall of) the outlet diffuser section of the volute, and the plurality of guide vanes are used to guide the gas flow direction from the circumferential direction to the axial direction; The tangential angle of the guide vane in the inlet direction is configured such that the ratio of the axial component to the circumferential component of the airflow along the flow direction of the guide vane at the inlet is consistent with the ratio of the axial component to the circumferential component of the velocity of the gas entering the guide vane; and the angle between the outlet direction of the guide vane and the turbine axis is 0°.

[0025] Specifically, the guide vane's trajectory is configured to satisfy an elliptical curve equation. This elliptical curve shape allows for a smooth transition in gas flow direction, gradually shifting from inlet to outlet. This helps reduce airflow separation and turbulence, lowers flow resistance, achieves efficient energy conversion, and improves turbine tip efficiency.

[0026] Specifically, the axial length of the guide vane is 0.8 to 2 times the diameter of the turbine outlet; in addition, since the gas passing through the turbine is affected by centrifugal force, the gas at the turbine outlet is more distributed in the area of 0.5RR relative to the turbine wheel diameter. Taking into account the efficiency loss that may be caused under other operating conditions, the width of the guide vane is 0.08 to 0.15 times the diameter of the turbine outlet.

[0027] Example 2 This embodiment provides a design method for a turbocharger volute assembly, comprising: S1. After the gas passes through the turbine and performs work, the velocity of the gas flowing out of the turbine and into the diffuser under the design operating conditions is obtained through CFD simulation calculations using software such as Fluent / CFX, and the axial and circumferential components of the gas velocity are obtained. S2, reference Figure 2 As shown, according to the axial component and circumferential component of the gas velocity, the ratio tanθ2 of the axial component v1 to the circumferential component v2 of the gas velocity entering the guide vane is obtained; that is, θ2=arctan(v1 / v2); S3. The tangential angle θ1 of the guide vane inlet direction is designed so that the ratio of the axial component to the circumferential component of the airflow along the guide vane flow direction at the inlet, tanθ1, is equal to tanθ2; that is, tanθ1=tanθ2; S4, reference Figure 4 As shown, the trajectory of the guide vane is configured as an elliptical curve, and the standard equation of the elliptical curve is: , Wherein, h and k are the coordinates of the center of the ellipse, 2a is the minor axis of the ellipse, and 2b is the major axis of the ellipse; the major axis of the ellipse is parallel to the Y axis, and the minor axis is parallel to the X axis; x∈(-a, 0), y∈(-b, 0); a and b satisfy 0.8D≤b≤2D, a<b, and D is the turbine outlet diameter.

[0028] S5. The tangent slope dy / dx at the starting position of the guide vane, i.e., at the inlet direction, is configured to satisfy the following relationship: dy / dx=tanθ1, and the angle between the outlet direction of the guide vane and the turbine axis is configured to be 0°; the width of the guide vane is 0.08-0.15 times the turbine outlet diameter.

[0029] S6. Obtain the trajectory line of the guide vane according to the relationship between the standard equation of the elliptic curve and the slope of the tangent line at the starting position of the guide vane.

[0030] S7. According to the trajectory of the guide vane, the efficiency value of the turbine end operating point is obtained by simulation calculation.

[0031] It should be noted that the turbine end operating point efficiency refers to the efficiency of energy conversion at the turbine end of the turbocharger under specific operating conditions (i.e., specific flow rate, speed, pressure ratio, etc. design points). Its efficiency calculation is often based on the turbine's isentropic efficiency or total efficiency. Turbine efficiency is the ratio of the actual work done by the fluid to the theoretical maximum work done. Efficiency = △W x / △W max； In actual turbocharger operation, changes in gas velocity and direction after passing through the guide vanes, as well as reduced efficiency caused by flow losses and turbulence, must be considered. Therefore, detailed modeling and calculation of the actual gas flow state are required through numerical simulation methods (such as CFD, computational fluid dynamics). This includes: Building a three-dimensional model. Based on the designed guide vane trajectory and the specific structural parameters of the volute and diffuser, a geometric model of the entire turbine outlet and diffuser is created using 3D modeling software (such as SolidWorks and CATIA). Meshing is then performed by importing the 3D model into CFD meshing software (such as ANSYS Meshing and ICEM CFD) for high-quality meshing. Boundary conditions are set: Pre-processing is performed in CFD simulation software (such as ANSYS Fluent and CFX), setting inlet boundaries (such as gas temperature, pressure, and velocity vector), outlet boundaries (pressure or flow), wall conditions (such as no slip), and specifying operating parameters (such as turbine speed and intake conditions). Select an appropriate fluid physics model (such as the Reynolds time-averaged NS equations) to physically model the gas flow and energy conversion process; start the simulation solver to perform numerical calculations until the flow field reaches a convergence state to ensure the accuracy and reliability of the results; post-processing analysis, extract key data in the post-processing module, including the gas velocity distribution, pressure distribution, temperature distribution, etc. at the turbine outlet, calculate the actual output power (such as outflow power or energy flow) of the gas after passing through the turbine, calculate the ideal output power based on the inlet conditions, and calculate the operating point efficiency value of the turbine end under the trajectory parameters based on the simulation results.

[0032] S8. In order to find the optimal trajectory curvature, it is necessary to adjust the optimal direction of the trajectory, that is, to find the best a and b values within the definition domain. By adjusting the a and b values, simulation calculations are performed within a limited range (0.8D≤b≤2D, a<b, D is the known turbine outlet diameter length); the turbine end efficiency values under different elliptical curve trajectories are obtained, and the trajectory line with the highest turbine end efficiency value is selected as the optimal trajectory line of the guide vane.

[0033] For example, for a1 and b1, the guide vane trajectory line L1 can be obtained; and the efficiency value eff1 of the turbine end operation point can be calculated in this case; assigning a2 and b2 to a and b respectively, the guide vane trajectory line L2 corresponding to a2 and b2 can be obtained; by different a n 、b n , n is a positive integer, we can get a n 、b n The corresponding guide vane trajectory line L n After simulation calculation and comparison, we can get the eff1, eff2...eff corresponding to the model of n trajectory lines. n , select the solution with the highest efficiency value as the optimal solution of the trajectory.

[0034] Figure 5 and Figure 6 They are respectively the outlet circumferential velocity distribution vector diagram without guide vanes and the outlet circumferential velocity distribution vector diagram after adding guide vanes. It can be seen that after adding the guide vanes of the present invention, the low-speed area in the circumferential velocity increases, indicating that the overall outlet circumferential velocity is reduced, and the reduced circumferential velocity is converted into axial velocity.

[0035] It should be noted that when the guide vanes are not set, the gas mainly flows in the circumferential direction after passing through the turbine outlet, the velocity vector shows a more obvious rotation distribution, the axial component of the gas is small, and the circumferential velocity energy is not fully utilized. After the guide vanes are set, the gas flow direction is effectively guided, so that the gas flow is changed from the original circumferential direction to a larger axial component. The guide vanes can redistribute the original circumferential airflow to an axial direction, thereby increasing the axial velocity, reducing the circumferential velocity, and achieving efficient energy transfer. Through the simulation of velocity vector distribution comparison, when the guide vanes are not added, the gas mainly flows in the circumferential direction, and the axial velocity component is relatively low. After adding the guide vanes with optimized design, the gas flow direction gradually changes to the axial direction, the flow field is more orderly, and the turbine end efficiency is significantly improved, which fully verifies the effectiveness of the technical solution of this embodiment.

[0036] In addition, through simulation calculations, the turbine end efficiency can be improved by 1-2% after adding guide vanes.

[0037] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A turbocharger volute assembly, characterized in that: The volute comprises a volute, wherein a plurality of guide vanes are distributed circumferentially inside an outlet diffuser section of the volute, and the plurality of guide vanes are used to guide the flow direction of the gas from the circumferential direction to the axial direction; The tangential angle of the guide vane in the inlet direction is configured such that the ratio of the axial component to the circumferential component of the airflow along the flow direction of the guide vane at the inlet is consistent with the ratio of the axial component to the circumferential component of the velocity of the gas entering the guide vane; and the angle between the outlet direction of the guide vane and the turbine axis is 0°.

2. A turbocharger volute assembly according to claim 1, characterized in that: The trajectory of the guide vane is configured to satisfy an elliptic curve equation.

3. The turbocharger volute assembly according to claim 1, characterized in that: The axial length of the guide vane is 0.8 to 2 times the diameter of the turbine outlet, and the width of the guide vane is 0.08 to 0.15 times the diameter of the turbine outlet.

4. A method for designing a turbocharger volute assembly, characterized in that: include: The velocity of the gas flowing out of the turbine and into the diffuser under the design working conditions is obtained through simulation calculation, and the axial component and circumferential component of the gas velocity are obtained; According to the axial component and the circumferential component of the gas velocity, a ratio tanθ2 of the axial component to the circumferential component of the gas velocity entering the guide vane is obtained; The tangential angle θ1 of the guide vane inlet direction is designed to make the ratio of the axial component to the circumferential component of the airflow along the flow direction of the guide vane at the inlet, tanθ1, equal to tanθ2; The trajectory of the guide vane is configured as an elliptical curve, and the standard equation of the elliptical curve is: ， Where h and k are the coordinates of the ellipse center, 2a is the minor axis of the ellipse, and 2b is the major axis of the ellipse. The major axis of the ellipse is parallel to the Y axis, and the minor axis is parallel to the X axis. x∈(-a, 0), y∈(-b, 0). a and b satisfy 0.8D≤b≤2D, a<b, and D is the turbine outlet diameter. The tangent slope dy / dx at the starting position of the guide vane, i.e., at the inlet direction, is configured to satisfy the following relationship: dy / dx=tanθ1, and the angle between the outlet direction of the guide vane and the turbine axis is configured to be 0°; According to the relationship between the standard equation of the elliptic curve and the slope of the tangent line at the starting position of the guide vane, the trajectory line of the guide vane is obtained; According to the trajectory of the guide vane, the efficiency value of the turbine end operating point is obtained by simulation calculation; By adjusting the values of a and b and performing simulation calculations within a limited range, the turbine end efficiency values under different elliptical curve trajectories are obtained, and the trajectory line with the highest turbine end efficiency value is selected as the optimal trajectory line of the guide vane.

5. The method for designing a turbocharger volute assembly according to claim 4, characterized in that: The width of the guide vane is 0.08 to 0.15 times the diameter of the turbine outlet.

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