Turbines and turbochargers
By setting a straight-line shape with a specific tilt angle at the leading edge of the turbine impeller blades, the problem of gas flow separation at the turbine impeller inlet is solved, thereby improving the turbine's efficiency and energy conversion performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-02-17
- Publication Date
- 2026-03-10
AI Technical Summary
In turbines where gas flows radially outward into the turbine impeller, gas flow separation and vortices are prone to occur at the turbine impeller inlet, leading to reduced efficiency.
The turbine impeller blades are designed with a specific tilt angle at the leading edge, which is between 0° and 45°, preferably between 10° and 30°, and the leading edge shape is straight, in order to reduce gas flow separation and the generation of vortices.
By optimizing the tilt angle of the blade leading edge, the efficiency of the turbine is effectively improved, especially in variable capacity turbines, where it significantly enhances the stability of gas flow and energy conversion efficiency.
Smart Images
Figure CN116568906B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a turbine and a supercharger. This application claims the benefit of priority of Japanese Patent Application No. 2021-044156 filed on March 17, 2021, and incorporates the content thereof by reference in this application. BACKGROUND
[0002] There is a type in which gas flows into a turbine wheel from a radially outer side in a turbine provided in a supercharger or the like. As a turbine of such a type, for example, a radial turbine in which gas flows in a radial direction is disclosed in Patent Literature 1. Further, a turbine in which gas flows in a direction inclined with respect to the radial direction is called an axial-radial turbine.
[0003] PRIOR ART DOCUMENTS
[0004] PATENT LITERATURE
[0005] Patent Literature 1: International Publication No. 2014 / 128898 SUMMARY
[0006] PROBLEMS TO BE SOLVED BY THE INVENTION
[0007] In a turbine of the type in which gas flows into a turbine wheel from a radially outer side, at an inlet portion of gas in the turbine wheel (i.e., a portion in the turbine wheel into which gas flows), separation of gas flow, generation of vortex flow, is sometimes caused depending on the operating conditions. If separation of gas flow is generated at the inlet portion of gas in the turbine wheel, the efficiency of the turbine is reduced.
[0008] An object of the present disclosure is to provide a turbine and a supercharger capable of improving the efficiency of the turbine.
[0009] SOLUTION TO THE PROBLEM
[0010] To solve the above problem, the turbine of the present disclosure is provided with: a turbine scroll flow path; a turbine wheel disposed radially inward of the turbine scroll flow path; and a blade body provided to the turbine wheel, which is inclined to the side opposite to the rotation direction side of the turbine wheel as it advances from the hub side to the shroud side, and has a leading edge having an inclination angle with respect to the central axis direction of the turbine wheel that is greater than 0° and is 45° or less when viewed in the radial direction.
[0011] It is preferable that the inclination angle of the leading edge be 10° or more and 30° or less.
[0012] It is preferable that the leading edge have a straight line shape.
[0013] To solve the above problem, the supercharger of the present disclosure is provided with the above turbine.
[0014] EFFECT OF THE INVENTION
[0015] According to the present disclosure, it is possible to improve the efficiency of a turbine. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1 is a brief sectional view of a supercharger according to an embodiment of the present disclosure.
[0017] Figure 2 is a sectional view at A-A section of Figure 1
[0018] Figure 3 is a view extracting a single-dot chain line portion of Figure 1
[0019] Figure 4 is a side view showing a turbine impeller according to an embodiment of the present disclosure.
[0020] Figure 5 is a graph showing a relationship between a pitch angle of a leading edge and a difference in efficiency of a turbine. DETAILED DESCRIPTION
[0021] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. The dimensions, materials, other specific numerical values and the like shown in the embodiment are merely examples for making understanding easy, and do not limit the present disclosure in the absence of specific description. Furthermore, in the present specification and the drawings, elements having substantially the same function or structure are denoted by the same reference signs, repeated description is omitted, and illustration of elements having no direct relation to the present disclosure is omitted.
[0022] Figure 1 is a brief sectional view of a supercharger TC. Hereinafter, the arrow L direction shown in Figure 1 will be described as a left side of the supercharger TC. The arrow R direction shown in Figure 1 will be described as a right side of the supercharger TC. As shown in Figure 1 , the supercharger TC is provided with a supercharger main body 1. The supercharger main body 1 includes a bearing housing 3, a turbine housing 5, and a compressor housing 7. The turbine housing 5 is linked to the left side of the bearing housing 3 by a fastening mechanism 9. The compressor housing 7 is linked to the right side of the bearing housing 3 by a fastening bolt 11. The supercharger TC is provided with a turbine T and a centrifugal compressor C. The turbine T includes the bearing housing 3 and the turbine housing 5. The centrifugal compressor C includes the bearing housing 3 and the compressor housing 7.
[0023] A protrusion 3a is provided on the outer peripheral surface of the bearing housing 3. The protrusion 3a is provided on the turbo housing 5 side. The protrusion 3a projects in the radial direction of the bearing housing 3. A protrusion 5a is provided on the outer peripheral surface of the turbo housing 5. The protrusion 5a is provided on the bearing housing 3 side. The protrusion 5a projects in the radial direction of the turbo housing 5. The bearing housing 3 and the turbo housing 5 are band fastened by a fastening mechanism 9. The fastening mechanism 9 is, for example, a G coupling. The fastening mechanism 9 clamps the protrusions 3a, 5a.
[0024] A bearing hole 3b is formed in the bearing housing 3. The bearing hole 3b penetrates in the left-right direction of the supercharger TC. A bearing is disposed in the bearing hole 3b. The rotating shaft 13 is inserted through the bearing. The bearing rotatably supports the rotating shaft 13. The bearing is a sliding bearing. However, the bearing is not limited to this, and can be a rolling bearing. A turbo impeller 15 is provided on the left end portion of the rotating shaft 13. The turbo impeller 15 is rotatably housed in the turbo housing 5. A compressor impeller 17 is provided on the right end portion of the rotating shaft 13. The compressor impeller 17 is rotatably housed in the compressor housing 7.
[0025] An intake port 19 is formed in the compressor housing 7. The intake port 19 opens on the right side of the supercharger TC. The intake port 19 is connected to an air cleaner, not shown. A diffusion flow path 21 is formed by the opposing surfaces of the bearing housing 3 and the compressor housing 7. The diffusion flow path 21 boosts the air. The diffusion flow path 21 is formed in a ring shape. The diffusion flow path 21 communicates with the intake port 19 on the radially inner side via the compressor impeller 17.
[0026] A compressor scroll flow path 23 is formed in the compressor housing 7. The compressor scroll flow path 23 is formed in a ring shape. The compressor scroll flow path 23 is, for example, located at a position radially outward of the diffusion flow path 21 with respect to the rotating shaft 13. The compressor scroll flow path 23 communicates with the intake port of an engine, not shown, and the diffusion flow path 21. If the compressor impeller 17 rotates, air is drawn into the compressor housing 7 from the intake port 19. The drawn-in air is pressurized and accelerated in the process of passing between the blades of the compressor impeller 17. The pressurized and accelerated air is boosted in the diffusion flow path 21 and the compressor scroll flow path 23. The boosted air is guided to the intake port of the engine.
[0027] The turbine housing 5 is formed with a discharge flow path 25, a housing portion 27, and an exhaust flow path 29. The discharge flow path 25 is open at the left side of the supercharger TC. The discharge flow path 25 is connected to an exhaust purification device, not shown. The discharge flow path 25 communicates with the housing portion 27. The discharge flow path 25 is continuous with the housing portion 27 in the rotational axis direction of the turbine impeller 15. The housing portion 27 houses the turbine impeller 15. The exhaust flow path 29 is formed at a position radially outward of the turbine impeller 15. The exhaust flow path 29 is formed in a ring shape. The exhaust flow path 29 includes a turbine scroll flow path 29a. The turbine scroll flow path 29a communicates with the housing portion 27. That is, the turbine impeller 15 is disposed at a position radially inward of the turbine scroll flow path 29a.
[0028] The exhaust flow path 29 communicates with an exhaust manifold of the engine, not shown. Exhaust gas discharged from the exhaust manifold of the engine, not shown, is guided to the discharge flow path 25 via the exhaust flow path 29 and the housing portion 27. The exhaust gas guided to the discharge flow path 25 rotates the turbine impeller 15 in the flow process.
[0029] The rotational force of the turbine impeller 15 is transmitted to the compressor impeller 17 via the rotational shaft 13. If the compressor impeller 17 rotates, air is boosted as described above. In this way, the air is guided to the intake port of the engine.
[0030] Figure 2 is Figure 1 a sectional view at A-A section of Figure 2 In the turbine housing 5, only the outer periphery is shown by a circle with respect to the turbine impeller 15. As shown in Figure 2 The exhaust flow path 29 is formed at a position radially outward of the housing portion 27 (i.e., radially outward of the turbine impeller 15). The exhaust flow path 29 has the turbine scroll flow path 29a, a communication portion 29b, an exhaust introduction port 29c, and an exhaust introduction path 29d.
[0031] The communication portion 29b is formed in a ring shape throughout the entire circumference of the housing portion 27. The turbine scroll flow path 29a is located at a position radially outward of the communication portion 29b with respect to the turbine impeller 15. The turbine scroll flow path 29a is formed in a ring shape throughout the entire circumference of the communication portion 29b (i.e., the entire circumference of the housing portion 27). The communication portion 29b communicates the housing portion 27 with the turbine scroll flow path 29a. A tongue portion 31 is formed in the turbine housing 5. The tongue portion 31 is provided at an end portion on the downstream side of the turbine scroll flow path 29a, and separates the portion on the downstream side of the turbine scroll flow path 29a from the portion on the upstream side.
[0032] The exhaust gas introduction port 29c is opened at the outside of the turbine housing 5. The exhaust gas discharged from an exhaust manifold of an engine not shown is introduced to the exhaust gas introduction port 29c. An exhaust gas introduction passage 29d is formed between the exhaust gas introduction port 29c and the turbine scroll flow passage 29a. The exhaust gas introduction passage 29d connects the exhaust gas introduction port 29c and the turbine scroll flow passage 29a. The exhaust gas introduction passage 29d is formed, for example, in a straight line shape. The exhaust gas introduction passage 29d guides the exhaust gas introduced from the exhaust gas introduction port 29c to the turbine scroll flow passage 29a. The turbine scroll flow passage 29a guides the exhaust gas introduced from the exhaust gas introduction passage 29d to the accommodation portion 27 via the communication portion 29b.
[0033] The bypass passage 33 is formed in the turbine housing 5. An inlet end OP of the bypass passage 33 is opened at the exhaust gas flow passage 29 (specifically, the exhaust gas introduction passage 29d). An outlet end of the bypass passage 33 is opened at the discharge flow passage 25 (refer to Figure 1 ). The bypass passage 33 communicates the exhaust gas introduction passage 29d and the discharge flow passage 25. An exhaust gas bypass port WP (refer to Figure 1 ) is formed at the outlet end of the bypass passage 33. An exhaust gas bypass valve WV (refer to Figure 1 ) capable of opening and closing the exhaust gas bypass port WP is disposed at the outlet end of the bypass passage 33. The exhaust gas bypass valve WV is disposed in the discharge flow passage 25. When the exhaust gas bypass valve WV opens the exhaust gas bypass port WP, the bypass passage 33 causes a part of the exhaust gas flowing in the exhaust gas introduction passage 29d to bypass the accommodation portion 27 (i.e., the turbine impeller 15) and flow out to the discharge flow passage 25.
[0034] In the turbine T, the flow rate of the exhaust gas flowing into the turbine impeller 15 is adjusted by controlling the opening and closing operation of the exhaust gas bypass port WP. In this way, the turbine T is a variable displacement type turbine. The bypass passage 33 and the exhaust gas bypass valve WV correspond to a flow rate adjustment mechanism that adjusts the flow rate of the exhaust gas flowing into the turbine impeller 15. However, as described below, the flow rate adjustment mechanism is not limited to the above example.
[0035] Figure 3 is a view that extracts the single-dotted line portion of Figure 1 . As shown in Figure 3 , the turbine impeller 15 has a hub 15a and a plurality of blade bodies 15b. Hereinafter, the central axis direction, the circumferential direction, and the radial direction of the turbine impeller 15 will be simply referred to as the central axis direction, the circumferential direction, and the radial direction. The hub 15a is connected to the left end portion of the rotation shaft 13 (refer to Figure 1 ). The outer diameter of the hub 15a becomes smaller toward the left side of the supercharger TC. A plurality of blade bodies 15b are provided on the outer peripheral surface of the hub 15a. The plurality of blade bodies 15b are provided at intervals in the circumferential direction. The blade bodies 15b are formed so as to extend from the outer peripheral surface of the hub 15a to the radially outer side. The outer edge of the blade body 15b includes a leading edge LE and a trailing edge TE.
[0036] The leading edge LE is the upstream edge of the blade body 15b in the direction of exhaust gas flow. The leading edge LE is the edge of the blade body 15b on the side closest to the turbine vortex flow path 29a. Exhaust gas flows in from the turbine vortex flow path 29a towards the leading edge LE. In other words, the portion of the turbine impeller 15 in which the leading edge LE is located corresponds to the exhaust gas inlet portion of the turbine impeller 15 (i.e., the portion of the turbine impeller 15 for which exhaust gas flows in). The leading edge LE is formed on the right end side of the blade body 15b. When viewed circumferentially, the leading edge LE extends along the central axis of the turbine impeller 15. Figure 3 In the example, the leading edge LE tilts radially outward as it advances along the central axis. However, when viewed circumferentially, the leading edge LE can also be parallel to the central axis.
[0037] The right end of the leading edge LE is the hub-side end P1 (i.e., the end on the side of the hub 15a). The left end of the leading edge LE is the shield-side end P2 (i.e., the end on the side of the shield 27a that forms the housing 27 in the turbine housing 5). The leading edge LE extends from the hub-side end P1 to the shield-side end P2.
[0038] The trailing edge TE is the downstream edge of the blade body 15b in the direction of exhaust gas flow. The trailing edge TE is the edge of the blade body 15b closest to the discharge flow path 25. Exhaust gas flows out from the trailing edge TE toward the discharge flow path 25. The trailing edge TE is formed on the left end side of the blade body 15b. When viewed circumferentially, the trailing edge TE extends radially. Specifically, the trailing edge TE extends radially while being twisted circumferentially.
[0039] The portion between the leading edge LE and the trailing edge TE of the outer periphery of the blade body 15b extends along the shroud 27a of the turbine housing 5.
[0040] like Figure 3 As indicated by arrow FD, exhaust gas flows radially into the turbine impeller 15 from the radially outer side. Thus, turbine T is a radial turbine. Alternatively, turbine T could also be a mixed-flow turbine where exhaust gas flows radially outward in a direction inclined relative to the radial direction.
[0041] Here, in the turbine T of the type in which gas flows in from the radially outer side toward the turbine wheel 15, separation of the gas flow, generation of a vortex, is sometimes caused at the inlet portion of the exhaust gas in the turbine wheel 15 depending on the operating condition. In the turbine T as a variable displacement type turbine, the operating condition (specifically, the flow rate of the exhaust gas flowing into the turbine wheel 15 and the like) varies over a wide range. Therefore, in the turbine T as a variable displacement type turbine, separation of the gas flow is particularly likely to occur at the inlet portion of the exhaust gas in the turbine wheel 15. Such separation of the gas flow is an important cause of reduction in the efficiency of the turbine T. In the turbine T as a variable displacement type turbine, the necessity of improving the efficiency of the turbine T is particularly high.
[0042] Therefore, in the turbine T of the present embodiment, the shape of the blade body 15b of the turbine wheel 15 is studied in order to improve the efficiency of the turbine T. Hereinafter, the shape of the blade body 15b of the turbine wheel 15 is described in detail with reference to Figure 4 and Figure 5 .
[0043] Figure 4 is a side view showing the turbine wheel 15 of the present embodiment. The leading edge LE of the blade body 15b of the turbine wheel 15 is inclined to the side opposite to the rotation direction RD side as it advances from the hub 15a side toward the shroud 27a side. That is, with respect to each blade body 15b, the circumferential position of the hub side end portion P1 of the leading edge LE is on the rotation direction RD side than the circumferential position of the shroud side end portion P2 of the leading edge LE. In the example of Figure 4 , when the turbine wheel 15 is viewed from the left side of the supercharger TC (i.e., the upper side in Figure 4 , the rotation direction RD is the counterclockwise direction.
[0044] The leading edge LE has a straight line shape. Specifically, the leading edge LE extends on a straight line connecting the hub side end portion P1 and the shroud side end portion P2. However, the shape of the leading edge LE is not limited to the straight line shape. For example, a part of the leading edge LE can also be curved or bent.
[0045] The inventors obtained the following insight by conducting a flow analysis simulation: the efficiency of the turbine T varies depending on the inclination angle al of the leading edge LE with respect to the central axis direction AD of the turbine wheel 15, as viewed in the radial direction. In the flow analysis simulation, the conditions of gas flow (e.g., direction, velocity, entropy, etc.) in the turbine wheel 15 and the efficiency of the turbine T were calculated for various variations of the inclination angle al. In particular, it was found from the flow analysis simulation that the efficiency of the turbine T is higher when the leading edge LE is inclined to the side opposite the direction of rotation RD of the turbine wheel 15 as it progresses from the hub 15a side to the shroud 27a side, and when the inclination angle al is set within a certain range. As a result, in the turbine T of the present embodiment, the inclination angle al of the leading edge LE is greater than 0° and is 45° or less. Thus, an increase in the efficiency of the turbine T is achieved.
[0046] Figure 5 is a graph showing the relationship between the inclination angle al [deg] of the leading edge LE and the efficiency difference AE [%] of the turbine T. Figure 5 is a graph obtained by flow analysis simulation. The efficiency difference AE of the turbine T is the amount of change in the efficiency of the turbine T for each inclination angle al, relative to the efficiency of the turbine T when the inclination angle al is 0°. That is, the efficiency difference AE is obtained by subtracting the efficiency of the turbine T when the inclination angle al is 0° from the efficiency of the turbine T for each inclination angle al. The efficiency of the turbine T is the ratio of the energy generated by the turbine T to the energy input to the turbine T.
[0047] As can be seen from the graph shown in Figure 5 , the efficiency of the turbine T is higher when the inclination angle al of the leading edge LE is greater than 0° and is 45° or less, as compared to when the inclination angle al is 0° or less or when the inclination angle al is greater than 45°. Furthermore, when the inclination angle al is 0° or less, the leading edge LE is parallel to the central axis direction AD, or the leading edge LE is inclined to the direction of rotation RD of the turbine wheel 15 as it progresses from the hub 15a side to the shroud 27a side.
[0048] In the flow analysis simulation, it was observed that, when the inclination angle al of the leading edge LE is greater than 0° and is 45° or less, separation of gas flow and generation of a vortex flow due to separation are suppressed in the portion of the turbine wheel 15 where the leading edge LE is disposed (i.e., the inlet portion of the exhaust gas in the turbine wheel 15). That is, when the inclination angle al of the leading edge LE is greater than 0° and is 45° or less, it is believed that the efficiency of the turbine T is higher as a result of the suppression of separation of gas flow.
[0049] According to the flow analysis simulation, it is known that in the case where the leading edge LE inclines to the side opposite to the rotation direction RD side of the turbine impeller 15 as it advances from the hub 15a side to the shroud 27a side, the impact at the time when the exhaust gas flowing from the leading edge LE collides with the blade body 15b is moderated, and the generation of vortexes in the flow of the exhaust gas is suppressed. On the other hand, it is known that if the inclination angle al of the leading edge LE is too large, after the exhaust gas flowing from the leading edge LE collides with the blade body 15b, the flow of the exhaust gas is difficult to follow along the blade body 15b, and instead separation of the gas flow is easily generated.
[0050] In Figure 5 In the graph shown in FIG. 6, in the case where the inclination angle al of the leading edge LE is about 20°, the efficiency difference AE of the turbine T takes a maximum value. Thus, according to the graph shown in FIG. 6, it is known that in the case where the inclination angle al of the leading edge LE is 10° or more and 30° or less, the efficiency of the turbine T is particularly high. Figure 5
[0051] In the flow analysis simulation, it is observed that in the case where the inclination angle al of the leading edge LE is 10° or more and 30° or less, in the portion of the turbine impeller 15 in which the leading edge LE is disposed (i.e., the inlet portion of the exhaust gas in the turbine impeller 15), separation of the gas flow and the generation of vortexes caused by the separation are effectively suppressed. That is, it is considered that in the case where the inclination angle al of the leading edge LE is 10° or more and 30° or less, separation of the gas flow is effectively suppressed, and thus the efficiency of the turbine T is effectively high.
[0052] As described above, in the turbine T, the leading edge LE has a straight line shape. Thus, based on the insight obtained from the flow analysis simulation, the inclination angle al is appropriately made appropriate to increase the efficiency of the turbine T.
[0053] The above-described embodiments of the present disclosure are described with reference to the drawings, but the present disclosure is not limited to such embodiments, as is apparent. It will be apparent to those skilled in the art that various modifications or changes can be conceived within the scope of the claims, and it should be understood that such modifications or changes certainly belong to the technical scope of the present disclosure.
[0054] In the above, an example in which the turbine T is a single scroll type (a type in which the number of turbine scroll flow passages 29a is one) is described, but the type of the turbine T is not limited to the above-described example. For example, the turbine T can be a double scroll type (a type in which two turbine scroll flow passages 29a are connected to the housing 27 at different circumferential positions), or a paired scroll type (a type in which two turbine scroll flow passages 29a are arranged in the axial direction).
[0055] In the foregoing, as the flow rate adjusting mechanism that adjusts the flow rate of the exhaust gas flowing into the turbine wheel 15, the example in which the bypass passage 33 and the exhaust gas bypass valve WV are used is described. However, the flow rate adjusting mechanism is not limited to the foregoing example. For example, as the flow rate adjusting mechanism, a mechanism including a plurality of variable nozzle vanes that can adjust the flow passage cross-sectional area of the flow passage on the upstream side from the turbine wheel 15 can be used. The plurality of variable nozzle vanes are provided on the radially outer side with respect to the turbine wheel 15. The plurality of variable nozzle vanes are provided at intervals in the circumferential direction of the turbine wheel 15. By the variable nozzle vanes turning, the flow passage cross-sectional area of the flow passage on the upstream side from the turbine wheel 15 changes according to the turning angle of the variable nozzle vanes. Thereby, the flow rate of the exhaust gas flowing into the turbine wheel 15 is adjusted. Further, the flow rate adjusting mechanism can not be provided on the turbine T. Both the flow rate adjusting mechanism including the exhaust gas bypass valve WV and the flow rate adjusting mechanism including the variable nozzle vanes can be provided on the turbine T.
[0056] In the foregoing, the example in which the turbine T is provided on the supercharger TC is described. However, the turbine T can be provided on another device other than the supercharger TC.
[0057] Explanation of symbols
[0058] 15 - turbine wheel, 15a - hub, 15b - vane body, 27a - shroud, 29a - turbine scroll flow passage, AD - center axis direction, LE - leading edge, RD - rotation direction, T - turbine, TC - supercharger, al - inclination angle.
Claims
1. A turbomachine, characterized in that, Possessing: A turbine scroll flow path; A turbine impeller disposed radially inward of the turbine scroll flow path; and A blade body provided to the turbine impeller, which is inclined to the side opposite to the direction of rotation of the turbine impeller as it advances from the hub side to the shroud side, and which has a leading edge having a straight shape with an inclination angle with respect to the central axis direction of the turbine impeller that is greater than 0° and is 45° or less when viewed in the radial direction, The inclination angle is constant from the hub side to the shroud side.
2. The turbine according to claim 1, characterized in that: The inclination angle of the leading edge is 10° or more and 30° or less.
3. A supercharger characterized by: Possessing the turbine according to claim 1 or 2.
Citation Information
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