Flow guide structure for pneumatic resistance reduction of high-speed motor train unit, apron board assembly, motor train unit and method

Abstract

The invention discloses a flow guide structure for pneumatic resistance reduction of a high-speed motor train unit. The flow guide structure is integrally formed on the side lower portion of a bogie apron board and / or an equipment compartment apron board and extends in the length direction of the corresponding apron board. The flow guide structure is used for actively inducing airflow to generate a guide effect at the position; the change of the flow direction of the airflow is used for inhibiting the downward rolling of the main airflow on the vehicle side to the bogie area below the vehicle, and / or reducing the generation and the scale of disordered vortexes in a bogie cabin; the flow guide structure comprises a flow guide main body extending outwards, the two ends of the flow guide main body are smoothly connected with the corresponding apron boards through wedge-shaped sections, the connection roots of the flow guide main body and the apron boards are in transition through arc surfaces, and the arc surfaces are bent towards the inner side of the bottom of the motor train unit. According to the flow guide structure, a guide airflow is induced to be generated when a train runs through a specific geometric shape, the two ends of the structure adopt wedge-shaped design, and the resistance introduced by the structure is reduced with a high slenderness ratio.

Description

Technical Field

[0001] This invention relates to the field of high-speed rail transit, and more specifically, to a flow guide structure, skirt assembly, train set, and method for aerodynamic drag reduction in high-speed train sets. Background Technology

[0002] With the rapid development of high-speed trains in my country, train speeds have exceeded 400 km / h. This has led to an exponential increase in aerodynamic drag, which accounts for over 95% of total operating drag. Therefore, aerodynamic drag reduction is crucial for reducing operating energy consumption and improving economic efficiency.

[0003] Traditional aerodynamic drag reduction methods mainly focus on optimizing the streamlined shape of the train head and improving the smoothness of the train surface. After years of in-depth research and product iteration, the streamlined and smoothed design of high-speed trains has approached the optimal solution, and the space for further drag reduction through traditional methods is extremely limited.

[0004] The presence of blunt-body structures such as bogies and windshields at the bottom of high-speed trains creates a highly turbulent flow field, which is extremely detrimental to aerodynamic drag control. The bogie area, especially in the middle carriages, has become one of the main sources of aerodynamic drag. The undercarriage area is the area of ​​greatest concern in the daily operation and maintenance of high-speed trains, as maintenance personnel frequently open and disassemble the skirts. To avoid reducing maintenance efficiency and increasing the difficulty of maintenance, it is not advisable to design complex additional structures on the skirts. Summary of the Invention

[0005] The purpose of this invention is to provide a flow guide structure, skirt assembly, train set and method for aerodynamic drag reduction of high-speed train sets, which can effectively improve the undercarriage flow field of high-speed train sets, significantly reduce aerodynamic drag, and has the advantages of simple structure and no impact on daily maintenance.

[0006] The embodiments of the present invention are implemented as follows: In a first aspect, this application provides a flow-guiding structure for aerodynamic drag reduction in high-speed trains. The flow-guiding structure is integrally formed on the lower side of the bogie skirt and / or equipment compartment skirt, and extends along the length direction corresponding to the skirt. The flow-guiding structure is used to actively induce airflow guidance at its location. The change in airflow direction is used to suppress the downward roll of the mainstream airflow on the side of the car towards the bogie area below the car, and / or to reduce the generation and size of turbulent vortices in the bogie compartment. The flow guiding structure includes an outwardly extending flow guiding body. The two ends of the flow guiding body are smoothly connected to the corresponding skirt through wedge-shaped segments. The connection root between the flow guiding body and the skirt is transitioned by an arc surface, and the arc surface bends towards the inner side of the bottom of the EMU.

[0007] In a possible implementation, the ratio H / L of the positioning height H of the flow guide structure to its width L satisfies: 1.5 ≤ H / L ≤ 3; and / or, the ratio L / D of the width L of the flow guide structure to the diameter D of the arc surface satisfies: 1 ≤ L / D ≤ ​​2.

[0008] In a possible implementation, the ratio H / L is 2 and the ratio L / D is 1.33.

[0009] In a possible implementation, the positioning height H of the flow guide structure is 80mm±5mm, the width L is 40mm±5mm, and the diameter D of the arc surface is 30mm±5mm.

[0010] In a possible implementation, the ratio L0 of the length of the wedge segment to the width L of the flow guide structure, L0 / L, satisfies: 3.5 ≤ L0 / L ≤ 4.5.

[0011] Secondly, this application also provides a high-speed train skirt assembly, including a skirt and the aforementioned airflow guiding structure; the skirt is provided in multiple manner and is located on one side of the bottom of the train body along the length direction of the train, so as to generate a stable rectification effect when the train is running in all directions and avoid visual discontinuities caused by installation errors.

[0012] Thirdly, the embodiments of this application also provide a high-speed train, including the aforementioned high-speed train skirt assembly.

[0013] Fourthly, this application also provides an optimized design method for the aforementioned aerodynamic drag reduction guide structure used in high-speed trains, comprising the following steps: Based on the dynamic clearance space constraints of the EMU, a parameterized model is established with the positioning height H, width L and arc diameter D of the guide structure as variables. The surface response method is adopted, with minimizing the aerodynamic drag coefficient of the whole vehicle as the primary objective and reducing the average vortex intensity in the bogie compartment area as a secondary objective, and multi-objective optimization analysis is performed on H, L, and D. Based on the constructed response surface, determine the optimal combination of parameters that simultaneously satisfies the primary objective and the collaborative objective.

[0014] The beneficial effects of the embodiments of the present invention are: This airflow guiding structure, through its specific geometric shape, induces airflow and provides guidance during train operation. Rooted in the lower side of the skirt panel, its key characteristic parameters include positioning height H, width L, and arc diameter D. The structure employs a wedge design at both ends, with the ratio of wedge length L0 to width L set at 4 to reduce drag introduced by its high aspect ratio. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the aerodynamic drag reduction guide structure of the present invention installed on the skirt plate for high-speed trains; Figure 2 This is a schematic diagram of the characteristic parameters of the flow guiding structure of the present invention; Figure 3 This is a schematic diagram of the wedge-shaped section at the end of the flow guiding structure of the present invention; Figure 4 This is a schematic diagram of the dynamic clearance space for high-speed trains. Figure 5 The diagram illustrates the installation of the airflow guiding structure on the EMU (Electric Multiple Unit). Figure 6 A velocity cloud map of the undercarriage flow field under the original working conditions; Figure 7 A velocity contour map of the undercarriage flow field after the application of the flow guiding structure; Figure 8 The vector diagram of the speed inside the bogie cabin under the original operating conditions; Figure 9 This is a vector diagram of the speed inside the bogie cabin after the application of the flow guidance structure.

[0017] Icons: 1. High-speed train; 2. Skirt; 3. Guide structure; 31. Guide body; 32. Wedge-shaped section; 33. Arc surface. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0021] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0022] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0023] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] Example 1 This embodiment provides a flow-guiding structure for aerodynamic drag reduction in high-speed trains. The flow-guiding structure 3 is integrally formed on the lower side of the bogie skirt 2 and / or equipment compartment skirt 2, and extends along the length of the corresponding skirt 2. The flow-guiding structure 3 is configured to actively induce a guiding airflow at its location. This guiding airflow can suppress the downward roll of the mainstream airflow on the side of the car towards the bogie area, and also reduce the generation and size of turbulent vortices in the bogie compartment. The flow-guiding structure 3 includes an outwardly extending flow-guiding body 31. The two ends of the flow-guiding body 31 are smoothly connected to the skirt 2 through wedge-shaped sections 32. The connection root between the flow-guiding body 31 and the skirt 2 body is transitioned by an arc surface 33, and the arc surface 33 bends towards the inner side of the bottom of the train.

[0025] refer to Figures 1 to 3The airflow guiding structure 3, through a specific geometric shape, induces a guiding airflow during train operation. This structure is rooted in the lower side of the skirt 2, and its key characteristic parameters include positioning height H, width L, and arc surface diameter D. The two ends of the structure adopt a wedge design, and the ratio of the length L0 of the wedge segment 32 to the width L is set to 4, so as to reduce the drag introduced by itself with a high length-to-slenderness ratio.

[0026] Using the aforementioned multi-objective collaborative optimization design method, a set of optimal parameters was determined: H=80mm, L=40mm, D=30mm. This parameter combination ensures that the structure does not exceed the specified limits. Figure 4 The dynamic bounded space is shown.

[0027] refer to Figures 5 to 9 The structure and skirt 2 are preferably integrally molded from glass fiber reinforced plastic using a specialized mold, ensuring precision and strength. In actual vehicle applications, the EMU equipped with the flow-guiding structure 3 of this invention exhibits a significant reduction in the turbulence of the undercarriage flow field, and a marked decrease in the intensity of eddy currents and the entrainment velocity within the bogie compartment.

[0028] Furthermore, the ratio H / L of the positioning height H of the flow guide structure 3 to its width L satisfies: 1.5 ≤ H / L ≤ 3; the ratio L / D of the width L of the flow guide structure 3 to the diameter D of the arc surface satisfies: 1 ≤ L / D ≤ ​​2. Preferably, the ratio H / L is 2 and the ratio L / D is 1.33. The positioning height H of the flow guide structure 3 is 80mm ± 5mm, the width L is 40mm ± 5mm, and the diameter D of the arc surface is 30mm ± 5mm. The ratio L0 of the length L0 of the wedge segment 32 to the width L of the flow guide structure 3, L0 / L, satisfies: 3.5 ≤ L0 / L ≤ 4.5.

[0029] Referring to Table 1, the actual train running resistance test data further verified the effectiveness of the invention. As shown in Table 1, the total drag coefficient of the entire train decreased from 0.6069 to 0.5885, a reduction of 3.04%. The drag reduction effect was mainly concentrated in the middle cars (such as cars 4, 5, and 7, where the drag decreased significantly), while the drag of the head car (car 1) and the tail car (car 8) remained basically unchanged or even increased slightly. This proves that the flow guiding structure 3 does not simply push the air away, but achieves optimized redistribution of aerodynamic load through ingenious flow field reconstruction, achieving the goal of systematic drag reduction by sacrificing local factors to optimize the overall system.

[0030]

[0031] Table 1 By inducing directional airflow through the aforementioned guide structure 3, active management of the flow field at the bottom of the train is achieved. Analysis of resistance distribution data reveals that this structure, by reconstructing the aerodynamic load distribution, achieves the optimal solution of "sacrificing minor local resistance in the first and last cars in exchange for significant resistance gains in the middle cars." Specifically, the resistance coefficients of the first (car 1) and last (car 8) remain essentially unchanged or increase slightly (change <2.5%), while the resistance coefficients of the middle cars (such as cars 4, 5, and 7) decrease significantly (maximum reduction of 9%), ultimately achieving a net resistance reduction of approximately 3% for the entire train. Real-world testing verifies that the guide structure 3 in this embodiment can bring at least a 2% drag reduction effect to high-speed trains with speeds up to 400 km / h, and is estimated to save an average of approximately 140,000 kWh of electricity per train per year, demonstrating significant economic benefits.

[0032] Example 2 This embodiment of a high-speed train skirt assembly includes a skirt 2 and a flow guiding structure 3. The flow guiding structure 3 is set as one on a single skirt 2. Multiple skirts 2 are provided and are located on one side of the bottom of the train body along the length direction of the train, so as to generate a stable rectification effect when the train is running in all directions and avoid visual discontinuity caused by installation errors.

[0033] Example 3 One embodiment of the high-speed train includes the high-speed train skirt assembly of embodiment 2, wherein the number of intermediate cars on which the skirt assembly is installed is at least 6.

[0034] Example 4 This embodiment presents an optimization design method that applies a surface response design approach. Within the allowable space, it designs the positioning height H, width L, and arc diameter D of the air knife rectifying structure using a horizontal orthogonal simulation analysis of three factors. Computational fluid dynamics software is used for numerical calculations. Based on the aerodynamic drag calculation results for each working condition, a response surface is constructed to obtain the optimal combination of characteristic parameters for the air knife rectifying structure: H=80mm, L=40mm, D=30mm. The specific steps include: Step S10: Based on the dynamic clearance space constraints of the high-speed train, establish a parameterized model with the positioning height H, width L and arc diameter D of the guide structure 3 as variables. Numerical calculations were performed using the mainstream commercial computational fluid dynamics software Star CCM+. The calculation model was an 8-car trainset of a certain type of high-speed train. The computational mesh adopted a cut volume mesh, and the entire computational domain was subjected to four levels of mesh refinement. The minimum mesh size was 25mm, and the maximum mesh size was 800mm. Three boundary layers were set on the train surface. The Y+ of the train surface was all within the range of 30~200. The total number of meshes was 56 million.

[0035] Step S20: Using the surface response method, with minimizing the aerodynamic drag coefficient of the entire vehicle as the primary objective and reducing the average vortex intensity in the bogie bay area as the secondary objective, multi-objective optimization analysis is performed on H, L, and D. The k-ω SST model was selected for the turbulence model, with incompressible air density and steady-state separation solution. The computational domain inlet was set as a velocity inlet boundary condition with a velocity of 111.11 m / s; the computational domain outlet was set as a pressure outlet boundary condition with a pressure of 0 Pa to simulate the natural environment; the ground was set as a moving wall boundary condition with a velocity of 111.11 m / s in the same direction as the inlet airflow.

[0036] Step S30: Based on the constructed response surface, determine the optimal parameter combination that simultaneously satisfies the primary objective and the collaborative objective.

[0037] The calculation results are shown in Table 1. The high-speed train with the array-arranged air knife rectification structure of this invention exhibits a 3% reduction in aerodynamic drag compared to the original high-speed train. The under-vehicle flow field visualization results are shown in Table 1. Figure 5 As shown, the air knife rectifying structure effectively improves the turbulence of the flow field under the car and reduces the eddy current intensity. The velocity vector diagram inside the bogie cabin is shown below. Figure 6 As shown, the "wind knife" rectification structure significantly suppresses the flow of air into the bogie cabin, and the air entrainment velocity at the lower edge of the bogie skirt 2 is significantly reduced, which is beneficial to reducing the aerodynamic drag of the bogie.

[0038] 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 flow-guiding structure for aerodynamic drag reduction in high-speed trains, characterized in that, The airflow guiding structure is integrally formed on the lower side of the bogie skirt and / or equipment compartment skirt, and extends along the length direction of the corresponding skirt; the airflow guiding structure is used to actively induce airflow guidance at its location; the change in airflow direction is used to suppress the downward roll of the mainstream airflow on the side of the car towards the bogie area below the car, and / or reduce the generation and size of turbulent vortices in the bogie compartment; The flow guiding structure includes an outwardly extending flow guiding body. The two ends of the flow guiding body are smoothly connected to the corresponding skirt through wedge-shaped segments. The connection root between the flow guiding body and the skirt is transitioned by an arc surface, and the arc surface bends towards the inner side of the bottom of the EMU.

2. The flow-guiding structure for aerodynamic drag reduction in high-speed trains according to claim 1, characterized in that, The ratio H / L of the positioning height H of the flow guide structure to its width L satisfies: 1.5≤H / L≤ 3; and / or, the ratio L / D of the width L of the flow guide structure to the diameter D of the arc surface satisfies: 1≤L / D≤2.

3. The flow-guiding structure for aerodynamic drag reduction in high-speed trains according to claim 2, characterized in that, The ratio H / L is 2, and the ratio L / D is 1.

33.

4. The flow-guiding structure for aerodynamic drag reduction in high-speed trains according to claim 3, characterized in that, The positioning height H of the flow guide structure is 80mm±5mm, the width L is 40mm±5mm, and the diameter D of the arc surface is 30mm±5mm.

5. The flow-guiding structure for aerodynamic drag reduction in high-speed trains according to claim 1, characterized in that, The ratio L0 of the length of the wedge segment to the width L of the flow guiding structure, L0 / L, satisfies: 3.5≤L0 / L≤4.

5.

6. A high-speed train skirt assembly, characterized in that, It includes a skirt and a flow guiding structure as described in any one of claims 1 to 5; the skirt is provided in multiple parts and is located on one side of the bottom of the train body along the length direction of the train set, so as to generate a stable flow straightening effect when the train is running in all directions and to avoid visual discontinuity caused by installation errors.

7. A high-speed train set, characterized in that, Includes the high-speed train skirt assembly as described in claim 6.

8. An optimized design method, applied to the aerodynamic drag reduction guide structure for high-speed trains as described in claim 1, characterized in that, Includes the following steps: Based on the dynamic clearance space constraints of the EMU, a parameterized model is established with the positioning height H, width L and arc diameter D of the guide structure as variables. The surface response method is adopted, with minimizing the aerodynamic drag coefficient of the whole vehicle as the primary objective and reducing the average vortex intensity in the bogie compartment area as a secondary objective, and multi-objective optimization analysis is performed on H, L, and D. Based on the constructed response surface, determine the optimal combination of parameters that simultaneously satisfies the primary objective and the collaborative objective.

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