Bogie bottom drag reduction cladding plate and high-speed train bogie thereof

Abstract

The application discloses a bogie bottom drag reduction cladding plate and a high-speed train bogie, and the cladding plate comprises a torsion bar cladding plate for cladding a torsion bar of a bogie frame, a first cladding plate for connecting a cross beam on one side of the torsion bar, and a second cladding plate for connecting a cross beam on the other side of the torsion bar. The first cladding plate and the torsion bar cladding plate form a first flow guide slope, the second cladding plate and the torsion bar cladding plate form a second flow guide slope, and the flow guide directions of the first flow guide slope and the second flow guide slope are symmetrically arranged. The application guides the airflow originally acting on the region near the center pin hole and the torsion bar to the lower side of the torsion bar cladding plate, optimizes the partial cladding and flow guide of the originally complex and abrupt bottom profile near the center pin hole and the torsion bar, forms a relatively continuous bottom flow guide surface, weakens the direct interference between the airflow and the complex components of the bottom, reduces the local flow separation, backflow and vortex intensity, improves the bogie bottom flow field distribution, and further achieves the purpose of reducing the aerodynamic drag of the bogie region.

Description

Technical Field

[0001] This invention relates to the field of high-speed train technology, specifically to a bogie bottom drag-reducing cover plate and its high-speed train bogie. Background Technology

[0002] As the operating speed of high-speed trains continues to increase, the proportion of aerodynamic drag in the total train drag is constantly growing. The bogie area, due to its complex shape, exposed components, and uneven bottom channels, is prone to significant flow separation, vortex structures, and pressure drag, making it a key target for local drag reduction optimization in high-speed trains. Existing review studies indicate that the bogie area, end-connection points, pantographs, and fairings—regions with localized irregularities—are key areas for further aerodynamic drag reduction design.

[0003] Existing technologies include solutions for incorporating covering structures and airflow guiding structures for the bottom of trains or bogie areas. However, these technologies primarily focus on airflow guiding at the front end of the car body bottom, overall bogie wrapping, or streamlined treatment of the frame and large components. For the central area of ​​the bogie bottom, the presence of the center pin mounting holes in the crossbeam and the torsion bar below the crossbeam results in overlapping components, limited space, and significant geometric abrupt changes. Airflow passing through this area is prone to local acceleration, separation, and reattachment, creating strong disturbances and increasing drag. Using only a large-scale wrapping solution often faces limitations in terms of installation space, motion envelope, maintenance accessibility, and structural weight. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of uneven flow, strong local disturbance, large resistance, and insufficient targeting of the central region in the bottom center area of ​​the bogie in the prior art. It provides a drag-reducing coating plate for the bottom of the bogie and its high-speed train bogie to improve the flow conditions around the bottom of the bogie, reduce local separation and eddy current intensity, thereby reducing the aerodynamic drag in the bogie area.

[0005] To achieve the above objectives, the present invention first discloses a bogie bottom drag-reducing covering plate for installation on the underside of the crossbeam of the bogie frame. The covering plate includes a torsion bar covering plate for covering the torsion bar of the bogie frame, a first covering plate for covering a portion of the upper center pin hole of the torsion bar, and a second covering plate for covering the other portion of the upper center pin hole of the torsion bar. The first covering plate and the torsion bar covering plate form a first guide slope, and the second covering plate and the torsion bar covering plate form a second guide slope.

[0006] The selection of the drag-reducing cladding plate at the bottom of the bogie is obtained through the following steps: S10. Establish a train geometric model and computational domain that includes the bogie region, and use computational fluid dynamics to perform numerical simulation on the bogie region to obtain numerical simulation results of the pressure field, velocity field and vorticity distribution in the bogie region. S20. Based on the numerical simulation results, the torsion bar and central pin hole area under the crossbeam are identified as the key disturbance area at the bottom. The identification criteria include: the formation of local high pressure area and significant negative pressure area in the above area, and the intense pressure gradient; the velocity field exhibits backflow, vortex and non-uniform height distribution. S30. Referring to the continuous curved surface and tapered contour structure of the manta ray's abdomen, parametrically model the bottom drag-reducing cover plate of the bogie to be designed, and design at least one candidate configuration of the bottom drag-reducing cover plate of the bogie. The candidate configuration includes at least: a curved surface configuration that only covers the center pin hole, a curved surface configuration that covers the center pin hole and the torsion bar, and a planar configuration that covers the center pin hole and the torsion bar. S40. For each candidate configuration, the aerodynamic drag of the bogie region is calculated by simulation, the correspondence between the candidate configuration and the drag is established, and the configuration with the optimal drag reduction rate is selected as the bogie bottom drag reduction cover plate configuration.

[0007] In one embodiment, step S10 includes: S110. Establish a computational domain for a 1:8 scaled-down three-car train model and a rail model that includes the geometric features of the bogie region. The inlet boundary of the computational domain adopts a velocity inlet boundary condition, the outlet boundary adopts a pressure outlet boundary condition, the top and two sides of the computational domain adopt symmetrical boundary conditions, and the boundary conditions of the ground and track are set as moving wall conditions opposite to the direction of train operation. S120. In Ansys Fluent fluid simulation software, a polyhedral-hexahedral core mesh is used to discretize the computational domain to obtain a finite number of mesh elements, and multiple local refinements are performed on the train head, parking space and bogie areas. S130. Based on a finite number of grid elements, the k-ω turbulence model is used to simulate the turbulence characteristics of the flow field around the train body and bogie area. The pressure field, velocity field and vortex distribution of the bogie area are obtained by calculation using Ansys Fluent fluid simulation software.

[0008] In one embodiment, step S120 includes: S122: After importing the train geometry model into Ansys Fluent fluid simulation software, create and export the size function field file; S124: Re-import the train geometry model, select the CFD surface mesh generation mode, import the size function field file, and generate the surface mesh for the bogie region; S126: Import the train geometry model again, select the CFD surface mesh generation mode, import the size function field file, and generate the air domain surface mesh. S128: After merging the surface meshes of the bogie region and the air domain, material points located outside the vehicle body and within the fluid domain are established to generate a volume mesh.

[0009] In one embodiment, step S40 includes: S410: Perform drag reduction evaluation simulation for each candidate configuration under multi-speed conditions, extract the total drag coefficient of the bogie region, and calculate the drag reduction rate of each candidate configuration; S420: Select the candidate configuration with the highest drag reduction rate as the final configuration of the drag reduction coating plate at the bottom of the bogie.

[0010] In one embodiment, the torsion bar covering plate is an arc-shaped covering plate that fits against the outer wall of the torsion bar, and the first and second flow guiding slopes are both transitioned to the torsion bar covering plate through an arc surface.

[0011] In one embodiment, the edges of the first and second covering plates are provided with snap-fit ​​positioning grooves for engaging with the motor suspension mount of the bogie frame.

[0012] A high-speed train bogie includes a bogie frame, on which a crossbeam, a torsion bar, and a motor suspension mount are disposed. A bottom drag-reducing covering plate is used, wherein the torsion bar and a center pin hole are encased within the bottom drag-reducing covering plate. A first covering plate is connected to the crossbeam on one side of the torsion bar, and a second covering plate is connected to the crossbeam on the other side of the torsion bar. A snap-fit ​​positioning groove engages with the motor suspension mount. A first and second guide slope direct airflow from the windward side to the area below the torsion bar covering plate.

[0013] In one embodiment, the length of the drag-reducing cover plate at the bottom of the bogie is the same as the length of the crossbeam to cover the torsion bar on the underside of the crossbeam, and the first guide ramp and the second guide ramp have a guide angle of 15°-25° relative to the underside of the crossbeam.

[0014] In one embodiment, the drag-reducing cover plate at the bottom of the bogie is connected to the crossbeam by screws, with at least some of the screws located behind the motor suspension mount to reduce the interference of the screw heads on the airflow.

[0015] In one embodiment, the first covering plate, the second covering plate and the underside of the crossbeam form a bonding plate, the connecting hole is provided on the bonding plate, and the screw passes through the connecting hole to bond the bonding plate to the crossbeam.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: This invention utilizes a first and a second guide slope formed on the drag-reducing coating plate at the bottom of the bogie to direct the airflow that would otherwise act on the area near the center pin hole and torsion bar to the area below the torsion bar coating plate. This locally covers and optimizes the complex and abrupt bottom shape near the center pin hole and torsion bar, creating a more continuous bottom guide surface. This reduces direct interference between the airflow and the complex bottom components, decreases local flow separation, backflow, and eddy intensity, and improves the flow field distribution at the bottom of the bogie, thereby reducing aerodynamic drag in the bogie area. Furthermore, the structure has a clear composition and a straightforward installation method, adapting to the limited space requirements at the bottom of the bogie while also considering structural rigidity, engineering feasibility, and ease of maintenance, thus possessing significant application value. Through computational fluid dynamics numerical simulation, the torsion bar and central pin hole areas beneath the crossbeam were identified as key disturbance regions at the bottom, giving the drag reduction design a clear direction. By designing multiple candidate configurations, simulating the drag of each configuration, establishing corresponding relationships, and selecting the one with the optimal drag reduction rate, the final selected bogie bottom drag reduction cladding plate was ensured to have the best drag reduction effect. Furthermore, this method can be extended to the design of other similar local drag reduction structures. Numerical simulation showed that the drag reduction rate of the bogie bottom drag reduction cladding plate obtained using the above method reached over 10.5%, exhibiting a relatively stable drag reduction effect at different speed levels. This indicates that the structure can effectively improve the flow field state in the coupling region and has good engineering application value. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is an axonometric schematic diagram of the drag-reducing cover plate at the bottom of the bogie disclosed in Embodiment 1 of the present invention.

[0018] Figure 2 This is a front view schematic diagram of the drag-reducing cover plate at the bottom of the bogie disclosed in Embodiment 1 of the present invention.

[0019] Figure 3 This is a top view schematic diagram of the drag-reducing cover plate at the bottom of the bogie disclosed in Embodiment 1 of the present invention.

[0020] Figure 4 This is an axonometric schematic diagram of a high-speed train bogie disclosed in Embodiment 1 of the present invention (bottom surface of the bogie facing upwards).

[0021] Figure 5 This is a top view schematic diagram of the high-speed train bogie disclosed in Embodiment 1 of the present invention.

[0022] Figure 6This is a data diagram showing drag reduction of a high-speed train using the high-speed train bogie disclosed in Embodiment 1 of the present invention under different speeds and operating conditions.

[0023] Figure 7 This is a schematic diagram of the drag reduction rate of a high-speed train at different speeds, based on the center pin hole and torsion bar curved surface covering scheme disclosed in Embodiment 1 of the present invention.

[0024] Figure 8 This is a bottom view schematic diagram of the drag-reducing cover plate at the bottom of the bogie disclosed in Embodiment 2 of the present invention.

[0025] Figure 9 The above are simulation comparison diagrams of pressure flow field slices of the two-car, one-position bogie disclosed in the preferred embodiment of the present invention. a) shows the bogie without the bottom drag-reducing cover plate, and b) shows the bogie with the bottom drag-reducing cover plate.

[0026] Figure 10 The above are simulation comparison diagrams of the velocity flow field slices of the two-car, one-position bogie disclosed in the preferred embodiment of the present invention. a) shows the bogie without the bottom drag-reducing cover plate, and b) shows the bogie with the bottom drag-reducing cover plate.

[0027] In the attached figures, the following labels are used: 1. Torsion bar cover plate; 2. First cover plate; 3. Second cover plate; 4. First guide slope; 5. Second guide slope; 6. Snap-fit ​​positioning groove; 7. Connecting hole; 8. Fitting plate; 10. Bogie frame; 101. Crossbeam; 102. Torsion bar; 103. Motor suspension seat; 104. Center pin hole. Detailed Implementation

[0028] To facilitate understanding of the present invention, a more comprehensive and detailed description of the invention will be provided below in conjunction with the accompanying drawings and preferred embodiments. However, the scope of protection of the present invention is not limited to the specific embodiments described below. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0029] Unless otherwise defined, all technical terms used below have the same meaning as commonly understood by those skilled in the art. The use of terms such as "a" or "an" in the specification and claims of this patent application does not indicate a quantity limitation, but rather indicates the presence of at least one. Terms such as "connected" or "linked" are not limited to direct connections, but can refer to indirect connections via other intermediate connecting elements. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; these relative positional relationships change accordingly when the absolute position of the described object changes.

[0030] Example 1: like Figures 1-8As shown, this embodiment of the invention provides a bogie bottom drag-reducing covering plate for installation on the underside of the crossbeam 101 of the bogie frame 10. It includes a torsion bar covering plate 1 for covering the torsion bar 102 of the bogie frame 10, a first covering plate 2 for covering a portion of the center pin hole 104 above the torsion bar 102, and a second covering plate 3 for covering the other portion of the center pin hole 104 above the torsion bar 102 (the center pin hole 104 is used to install a center pin, which is the rotatable connection between the bogie and the car body). The first covering plate 2, the second covering plate 3, and the crossbeam 101 of the bogie frame 10 are used to reduce drag. Beam 101 can be connected by welding, screws, etc. The first covering plate 2 and the torsion bar covering plate 1 form the first guide slope 4, and the second covering plate 3 and the torsion bar covering plate 1 form the second guide slope 5. The first guide slope 4 and the second guide slope 5 can be inclined planes or inclined arc surfaces. In order to facilitate forming, the torsion bar covering plate 1, the first covering plate 2 and the second covering plate 3 are integral stamping structures. The guide direction of the first guide slope 4 and the second guide slope 5 are opposite, so that the bogie can guide and reduce drag when moving in both directions. Therefore, the present invention, through the first guide slope 4 and the second guide slope 5 formed on the drag-reducing coating plate at the bottom of the bogie, guides the airflow that originally acted on the area near the center pin hole 104 and the torsion bar 102 to the area below the torsion bar coating plate 1. This allows the originally complex and abrupt bottom shape near the center pin hole 104 and the torsion bar 102 to be locally covered and optimized for airflow, thereby forming a more continuous bottom guide surface. This reduces the direct interference between the airflow and the complex bottom components, reduces local flow separation, backflow and eddy intensity, improves the flow field distribution at the bottom of the bogie, and thus achieves the purpose of reducing aerodynamic drag in the bogie area. At the same time, the structure has a clear composition and a clear installation method. It can not only adapt to the arrangement requirements of the limited space at the bottom of the bogie, but also take into account structural rigidity, engineering feasibility and maintenance convenience, and has good application value.

[0031] In this embodiment, the torsion bar covering plate 1 is an arc-shaped covering plate that fits against the outer wall of the torsion bar 102. The outer wall of the torsion bar 102 can provide support and positioning at the top, and the circular angle of the arc-shaped covering plate is 120°. The first guide slope 4 and the second guide slope 5 both transition to the torsion bar covering plate 1 through arc surfaces, thereby facilitating a smooth transition of airflow.

[0032] In this embodiment, the edges of the first covering plate 2 and the second covering plate 3 are provided with snap-fit ​​positioning grooves 6 for cooperating with the motor suspension seat 103 of the bogie frame 10. The snap-fit ​​positioning grooves 6 have three functions: firstly, they can avoid the motor suspension seat 103 and prevent interference; secondly, they can realize the rapid positioning of the drag-reducing covering plate at the bottom of the bogie on the crossbeam 101; and thirdly, they can improve the connection strength through snap-fit.

[0033] In this embodiment, the selection of the drag-reducing coating plate at the bottom of the bogie is obtained through the following steps: S10. Establish a train geometric model and computational domain including the bogie region, and use computational fluid dynamics to perform numerical simulation on the bogie region to obtain numerical simulation results of the pressure field, velocity field and vorticity distribution including the bogie region. Specifically, obtain detailed flow field information of the bogie region through CFD method, which provides a quantitative basis for subsequent identification of disturbance regions and design of the covering configuration, avoids the blindness of empirical design, and improves the pertinence of drag reduction scheme.

[0034] Based on multi-dimensional identification criteria of pressure field, velocity field and vortex distribution, it is possible to accurately pinpoint the torsion bar and central pin hole area under the crossbeam as one of the main sources of aerodynamic drag.

[0035] This region is characterized by significant component interlacing, limited space, and abrupt geometric changes: the torsion bar 102, a transversely arranged rod-shaped component, is exposed below the crossbeam, perpendicular or oblique to the mainstream direction, forming a distinct windward bulge. The center pin hole 104, located above the torsion bar, is a recessed structure for installing the center pin, forming a complex local configuration with the torsion bar, featuring a staggered, concave-convex combination. The crossbeam 101, as a load-bearing structure, has limited space beneath it; the torsion bar and center pin hole are compactly arranged in this area, forming a narrow and irregular flow channel. The geometric features of this region prevent smooth airflow, inevitably generating flow disturbances.

[0036] S20. Based on the numerical simulation results, the torsion bar and central pin hole area under the crossbeam are identified as the key disturbance area at the bottom. The identification criteria include: the formation of local high pressure area and significant negative pressure area in the above area, and the intense pressure gradient; the velocity field exhibits backflow, vortex and non-uniform height distribution. Numerical simulations of the flow field analysis of the original bogie reveal typical disturbance characteristics in this region: after the airflow impacts the torsion bar, the area around the center pin hole, and other protruding structures, a local high-pressure zone forms on the windward side; after the airflow bypasses the structures, it suddenly expands, forming a significant local low-pressure zone (significant negative pressure zone) on the leeward side; a sharp pressure gradient forms between the high-pressure and low-pressure zones, increasing pressure drag. From a velocity field perspective, local low-velocity or high-velocity shear zones appear in this region; after the airflow bypasses the structures, a recirculation zone or vortex forms; the velocity distribution exhibits high non-uniformity, with a significant velocity gradient. Due to geometric abrupt changes, the airflow cannot flow close to the body, resulting in boundary layer separation; the separated airflow forms a shear layer and a recirculation zone, increasing energy dissipation.

[0037] S30. Referring to the continuous curved surface and tapered contour structure of the manta ray's abdomen, parametrically model the bottom drag-reducing cover plate of the bogie to be designed, and design at least one candidate configuration of the bottom drag-reducing cover plate of the bogie. The candidate configuration includes at least: a curved surface configuration that only covers the center pin hole, a curved surface configuration that covers the center pin hole and the torsion bar, and a planar configuration that covers the center pin hole and the torsion bar. S40. For each candidate configuration, the aerodynamic drag of the bogie region is calculated by simulation, the correspondence between the candidate configuration and the drag is established, and the configuration with the optimal drag reduction rate is selected as the bogie bottom drag reduction cover plate configuration.

[0038] In one embodiment, step S10 includes: S110. Establish a computational domain for a 1:8 scaled-down three-car train model and a rail model that includes the geometric features of the bogie region. The inlet boundary of the computational domain adopts a velocity inlet boundary condition, the outlet boundary adopts a pressure outlet boundary condition, the top and two sides of the computational domain adopt symmetrical boundary conditions, and the boundary conditions of the ground and track are set as moving wall conditions opposite to the direction of train operation. S120. In Ansys Fluent fluid simulation software, a polyhedral-hexahedral core mesh is used to discretize the computational domain to obtain a finite number of mesh elements, and multiple local refinements are performed on the train head, parking space and bogie areas. S130. Based on a finite number of grid elements, the k-ω turbulence model is used to simulate the turbulence characteristics of the flow field around the train body and bogie area. The pressure field, velocity field and vortex distribution of the bogie area are obtained by calculation using Ansys Fluent fluid simulation software.

[0039] In one embodiment, step S120 includes: S122: After importing the train geometry model into Ansys Fluent fluid simulation software, create and export the size function field file; S124: Re-import the train geometry model, select the CFD surface mesh generation mode, import the size function field file, and generate the surface mesh for the bogie region; S126: Import the train geometry model again, select the CFD surface mesh generation mode, import the size function field file, and generate the air domain surface mesh. S128: After merging the surface meshes of the bogie region and the air domain, material points located outside the vehicle body and within the fluid domain are established to generate a volume mesh.

[0040] Generating separate surface meshes for the bogie region and the air region, followed by merging, ensures the mesh quality for the bogie's complex details and avoids overly coarse meshes in the bogie region or overly dense meshes in the air region due to a globally uniform mesh size. Controlling the mesh density transition through a size function field file effectively controls the overall mesh count while maintaining computational accuracy, thus improving computational efficiency.

[0041] In one embodiment, step S40 includes: S410: Perform drag reduction evaluation simulation for each candidate configuration under multi-speed conditions, extract the total drag coefficient of the bogie region, and calculate the drag reduction rate of each candidate configuration; S420: Select the candidate configuration with the highest drag reduction rate as the final configuration of the drag reduction coating plate at the bottom of the bogie.

[0042] See Figures 4-5 As shown, this invention discloses a high-speed train bogie, including a bogie frame 10. The bogie frame 10 is provided with a crossbeam 101, a torsion bar 102, and a motor suspension seat 103. The bogie bottom drag-reducing covering plate of this embodiment is used. A first covering plate 2 is connected to the crossbeam 101 on one side of the torsion bar 102, and a second covering plate 3 is connected to the crossbeam 101 on the other side of the torsion bar 102. A snap-fit ​​positioning groove 6 cooperates with the motor suspension seat 103. A first guide slope 4 and a second guide slope 5 guide the airflow on the windward side to the area below the torsion bar covering plate 1. Thus, in the high-speed train bogie, the airflow at the bottom of the torsion bar 102 area is redirected, causing the airflow to adhere more to the surface of the covering plate, thereby reducing the direct interaction with the original complex structure and achieving the effect of improving the local flow field and reducing aerodynamic drag.

[0043] In this embodiment, in order to maximize the drag reduction effect of the torsion bar 102, the length of the drag reduction cover plate at the bottom of the bogie is the same as the length of the crossbeam 101 to cover the torsion bar 102 on the underside of the crossbeam 101, that is, the drag reduction cover plate at the bottom of the bogie extends to both sides.

[0044] In this embodiment, the guiding angle between the first guiding slope 4 and the second guiding slope 5 and the lower side of the crossbeam 101 is 20°, which provides good guiding performance.

[0045] Example 2: In this embodiment, see Figure 8 The connection method is screw connection, which is convenient for assembly and disassembly. The edges of the first cover plate 2 and the second cover plate 3 are provided with connection holes 7, which are connected to the crossbeam 101 by screws. The drag-reducing cover plate at the bottom of the bogie is connected to the crossbeam 101 by screws. At least some of the screws are located behind the motor suspension seat 103 to reduce the interference of the screw heads on the airflow.

[0046] In this embodiment, optionally, in order to facilitate the installation of the drag-reducing cover plate at the bottom of the bogie and reduce the resistance caused by the gap, the first cover plate 2, the second cover plate 3 and the lower side of the crossbeam 101 are formed with a fitting plate 8. The fitting plate 8 can be formed in one-piece stamping or can be formed by screw connection. The connecting hole 7 is provided on the fitting plate 8, and the screw passes through the connecting hole 7 to fit the fitting plate 8 onto the crossbeam 101.

[0047] like Figure 9As shown, both the high-pressure and low-pressure areas of the original vehicle have been reduced, indicating that the drag-reducing cladding at the bottom of the bogie can mitigate the negative impact of pressure differential drag by reducing the pressure difference between the front and rear of the components. Furthermore, the cladding significantly improves the stability of the wake region; the turbulent vortices in the wake region under the original operating conditions are suppressed, such as... Figure 10 As shown, this optimization improves the overall flow field of the bogie and enhances its aerodynamic performance.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A drag-reducing covering plate for the bottom of a bogie, characterized in that, For installation on the underside of the crossbeam (101) of the bogie frame (10), it includes a torsion bar cover plate (1) for covering the torsion bar (102) of the bogie frame (10), a first cover plate (2) for covering a portion of the center pin hole (104) above the torsion bar (102), and a second cover plate (3) for covering the other portion of the center pin hole (104) above the torsion bar (102). The first cover plate (2) and the torsion bar cover plate (1) form a first guide slope (4), and the second cover plate (3) and the torsion bar cover plate (1) form a second guide slope (5). The selection of the drag-reducing cladding plate at the bottom of the bogie is obtained through the following steps: S10. Establish a train geometric model and computational domain including the bogie (10) region, and use computational fluid dynamics to perform numerical simulation on the bogie region to obtain numerical simulation results of the pressure field, velocity field and vortex distribution including the bogie region. S20. Based on the numerical simulation results, the area of ​​the torsion bar (102) and the central pin hole (104) below the crossbeam (101) is identified as the bottom key disturbance area; the identification criteria include: the formation of local high pressure area and significant negative pressure area in the above area, and the intense pressure gradient; the velocity field has backflow, vortex and height non-uniform distribution; S30. Referring to the continuous curved surface and tapered contour structure of the manta ray's abdomen, parametric modeling is performed on the bottom drag-reducing cover plate of the bogie to be designed, and at least one candidate configuration of the bottom drag-reducing cover plate of the bogie is designed. The candidate configuration includes at least: a curved surface configuration that only covers the center pin hole (104), a curved surface configuration that covers the center pin hole (104) and the torsion bar (102), and a planar configuration that covers the center pin hole (104) and the torsion bar (102). S40. For each candidate configuration, the aerodynamic drag of the bogie region is calculated by simulation, the correspondence between the candidate configuration and the drag is established, and the configuration with the optimal drag reduction rate is selected as the bogie bottom drag reduction cover plate configuration.

2. The bogie bottom drag-reducing covering plate according to claim 1, characterized in that, Step S10 includes: S110. Establish a computational domain for a 1:8 scaled-down three-car train model and a rail model containing the geometric features of the bogie (10) region. The inlet boundary of the computational domain adopts the velocity inlet boundary condition, the outlet boundary adopts the pressure outlet boundary condition, the top and two sides of the computational domain adopt the symmetric boundary condition, and the boundary conditions of the ground and track are set as moving wall conditions opposite to the direction of train operation. S120. In Ansys Fluent fluid simulation software, a polyhedral-hexahedral core mesh is used to discretize the computational domain to obtain a finite number of mesh elements, and multiple local refinements are performed on the train head, parking space and bogie areas. S130. Based on a finite number of grid elements, the k-ω turbulence model is used to simulate the turbulence characteristics of the flow field around the train body and bogie area. The pressure field, velocity field and vortex distribution of the bogie area are obtained by calculation using Ansys Fluent fluid simulation software.

3. The bogie bottom drag-reducing covering plate according to claim 2, characterized in that, Step S120 includes: S122: After importing the train geometry model into Ansys Fluent fluid simulation software, create and export the size function field file; S124: Re-import the train geometry model, select the CFD surface mesh generation mode, import the size function field file, and generate the surface mesh for the bogie region; S126: Import the train geometry model again, select the CFD surface mesh generation mode, import the size function field file, and generate the air domain surface mesh. S128: After merging the surface meshes of the bogie region and the air domain, material points located outside the vehicle body and within the fluid domain are established to generate a volume mesh.

4. The bogie bottom drag-reducing covering plate according to claim 1, characterized in that, Step S40 includes: S410: Perform drag reduction evaluation simulation for each candidate configuration under multi-speed conditions, extract the total drag coefficient of the bogie region, and calculate the drag reduction rate of each candidate configuration; S420: Select the candidate configuration with the highest drag reduction rate as the final configuration of the drag reduction coating plate at the bottom of the bogie.

5. The bogie bottom drag-reducing covering plate according to claim 1, characterized in that, The torsion bar covering plate (1) is an arc-shaped covering plate that fits against the outer wall of the torsion bar (102). The first guide slope (4) and the second guide slope (5) are both connected to the torsion bar covering plate (1) through a circular arc surface.

6. The bogie bottom drag-reducing covering plate according to claim 1, characterized in that, The edges of the first covering plate (2) and the second covering plate (3) are provided with snap-fit ​​positioning grooves (6) for cooperating with the motor suspension seat (103) of the bogie frame (10).

7. A high-speed train bogie, comprising a bogie frame (10), wherein a crossbeam (101), a torsion bar (102), and a motor suspension mount (103) are disposed on the bogie frame (10), characterized in that, The bogie bottom drag-reducing covering plate according to any one of claims 1-6 is used. The torsion bar (102) and the center pin hole (104) are covered in the bogie bottom drag-reducing covering plate. The first covering plate (2) is connected to the cross beam (101) on one side of the torsion bar (102). The second covering plate (3) is connected to the cross beam (101) on the other side of the torsion bar (102). The snap-fit ​​positioning groove (6) cooperates with the motor suspension seat (103). The first guide slope (4) and the second guide slope (5) guide the airflow on the windward side to the underside of the torsion bar covering plate (1).

8. The high-speed train bogie according to claim 7, characterized in that, The length of the drag-reducing cover plate at the bottom of the bogie is the same as the length of the crossbeam (101) to cover the torsion bar (102) on the underside of the crossbeam (101). The first guide slope (4) and the second guide slope (5) have a guide angle of 15°-25° relative to the underside of the crossbeam (101).

9. The high-speed train bogie according to claim 7, characterized in that, The drag-reducing cover plate at the bottom of the bogie is connected to the crossbeam (101) by screws, with at least some of the screws located behind the motor suspension mount (103) to reduce the interference of the screw heads on the airflow.

10. The high-speed train bogie according to claim 7, characterized in that, The first covering plate (2), the second covering plate (3) and the lower side of the cross beam (101) form a fitting plate (8), the connecting hole (7) is provided on the fitting plate (8), and the screw passes through the connecting hole (7) to fit the fitting plate (8) onto the cross beam (101).

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