A method and system for aerodynamic drag reduction of a train

Abstract

This application relates to the technical field of aerodynamic drag reduction, and in particular to a method and system for aerodynamic drag reduction of trains. The method includes: establishing a numerical simulation model of the train's aerodynamic characteristics, simulating and analyzing the turbulent flow field structure around the train, and determining specific flow locations associated with aerodynamic drag reduction; setting up blowing and suction control regions of different ranges at the specific flow locations, and analyzing and determining the active drag reduction control region with drag reduction effect; setting air vents in the active drag reduction control region, performing normal blowing and suction control through the air vents, analyzing and obtaining the variation curve of the aerodynamic drag reduction rate with train speed and blowing and suction control parameters, obtaining the normal blowing and suction mode with drag reduction effect and the critical velocity value based on the variation curve, and establishing a flow velocity control database; and performing active aerodynamic drag reduction control based on the flow velocity control database. This application achieves the effect of accurately determining the active drag reduction control region with drag reduction effect and performing aerodynamic drag reduction control at the required locations.

Description

Technical Field

[0001] This application relates to the field of train aerodynamic drag reduction technology, and in particular to a train aerodynamic drag reduction method and system. Background Technology

[0002] High speed is a constant theme in the development of rail transit. However, with the increase in train speed, aerodynamic drag reduction increases dramatically, leading to high energy consumption and posing new challenges to energy conservation and environmental protection. When the operating speed reaches 350 km / h, the aerodynamic drag of the train accounts for about 85% of the total drag of the entire vehicle, of which pressure difference drag is dominant and is the main consideration for drag reduction and energy saving in high-speed trains.

[0003] The formation of surface pressure drag on trains is closely related to changes in flow velocity, flow separation, and wake vortices in the surrounding turbulent flow field. For high-speed trains, streamlined shape optimization is the most effective drag reduction method. However, when the streamline length reaches a certain value, its drag reduction effect is limited, and it is difficult to achieve significant breakthroughs. The limitations of passive flow field control methods such as nose shape optimization become increasingly prominent. Therefore, international research has shifted its focus to active turbulent flow field control methods with great potential, such as tail slit jet aerodynamic drag reduction and low-density gas injection aerodynamic drag reduction. However, current active turbulent flow field control primarily aims to reduce frictional drag, neglecting the influence mechanism and drag reduction effect of air blowing and suction control, and the influence mechanism of the dominant aerodynamic pressure drag remains unclear. How to achieve precise aerodynamic drag reduction control at the required locations on high-speed trains remains a pressing problem to be solved. Summary of the Invention

[0004] Therefore, embodiments of this application provide a train aerodynamic drag reduction method, which can use a numerical simulation model of train aerodynamic characteristics to determine the turbulent flow field structure around the train, locate special flow positions associated with aerodynamic drag reduction, further analyze and determine the active drag reduction control region with drag reduction effect, set air holes in the active drag reduction control region, analyze the variation law of train aerodynamic drag reduction rate with the normal blowing and sucking velocity, establish a flow velocity control database, and perform active aerodynamic drag reduction control based on the flow velocity control database. The specific technical solution is as follows:

[0005] A numerical simulation model of train aerodynamic characteristics is established. The turbulent flow field structure around the train is determined using the numerical simulation model of train aerodynamic characteristics, and the special flow positions associated with aerodynamic drag reduction are located.

[0006] Different ranges of air blowing and suction control zones are set at the special flow position, and the drag reduction effect of the air blowing and suction control zones in the normal air blowing and normal air suction modes is analyzed on the numerical simulation model of the train aerodynamic characteristics. Based on the drag reduction effect, the active drag reduction control zone is determined, and air holes are set in the active drag reduction control zone.

[0007] Different normal blowing and suction speeds are set in the active drag reduction control area to obtain the variation law of train aerodynamic drag reduction rate with normal blowing and suction speed at different train running speeds, thereby obtaining the normal blowing and suction mode with drag reduction effect and the normal blowing and suction speed value, and establishing a flow rate control database.

[0008] Active aerodynamic drag reduction control is performed based on the aforementioned flow rate control database.

[0009] Furthermore, the step of performing active aerodynamic drag reduction control based on the flow rate control database includes:

[0010] Receive current train speed information, retrieve from the flow rate control database the normal blowing and suction mode with drag reduction effect and the normal blowing and suction speed value corresponding to the active drag reduction control area under the current train speed information;

[0011] Based on the normal blowing and suction mode with drag reduction effect and the normal blowing and suction velocity value, the direction of rotation and actual speed of the fan are determined, and the fan direction control command and speed control command are output; wherein, the fan direction is determined according to the normal blowing and suction mode, the initial gas flow rate is obtained based on the normal blowing and suction velocity value and the relationship between velocity and flow rate, the actual gas flow rate is obtained based on the initial gas flow rate, the system flow loss rate and the redundancy coefficient, and the actual speed of the fan is obtained based on the relationship between the actual gas flow rate and the speed.

[0012] Based on the fan steering control command and speed control command, the gas in the gas delivery pipeline is controlled to flow through the air pump and be blown out or drawn in through the air hole.

[0013] Furthermore, before being blown out or inhaled through the air hole, the procedure further includes:

[0014] The gas flowing through the air pump is controlled by a flow valve located near the wall of the vehicle body.

[0015] Furthermore, the steps for determining the turbulent flow field structure around the train using the aforementioned numerical simulation model of train aerodynamic characteristics include:

[0016] A realistic geometric model of the train structure was created using 3D software.

[0017] A numerical computation region is established in the actual geometric model of the train structure. The actual geometric model of the train structure is meshed, and the boundary conditions and turbulence model of the actual geometric model of the train structure are set.

[0018] Numerical simulation and visualization analysis of the velocity and pressure fields on the train surface are performed based on the actual geometric model of the train structure.

[0019] The relationship between the change in gas velocity on the train surface and the pressure on the train surface was obtained, and the development law of the boundary layer on the train surface and the location of boundary layer separation were determined by the velocity distribution curve.

[0020] Furthermore, the step of meshing the actual geometric model of the train structure includes:

[0021] The actual structural geometric model of the train is divided using a structured mesh strategy, an unstructured mesh strategy, a polyhedral mesh strategy, or a hybrid mesh strategy.

[0022] Furthermore, the step of determining the turbulent flow field structure around the train using the aforementioned numerical simulation model of train aerodynamic characteristics also includes:

[0023] The normalized residual order of magnitude of the flow field parameters of the actual train structural geometry model and the normalized residual order of magnitude of the turbulence model parameters are set to 10. -6 Each term in the discrete term is selected with a precision of second order or higher.

[0024] Furthermore, the specific flow locations associated with aerodynamic drag reduction include: boundary layer abrupt change sites, flow separation sites, flow reattachment sites, and vortex shedding sites.

[0025] One embodiment of this application also provides a train aerodynamic drag reduction system, which applies the train aerodynamic drag reduction method described above. The train aerodynamic drag reduction system includes a flow rate control module, a first regulation module, an air pump control module, and an air delivery control module.

[0026] The flow rate control module is used to receive the current train speed information and retrieve the normal blowing and suction mode and normal blowing and suction speed value corresponding to the active drag reduction control area under the current train speed information from the flow rate control database.

[0027] The flow rate control module is used to receive the current train speed information and retrieve the normal blowing and suction mode and normal blowing and suction speed value corresponding to the active drag reduction control area under the current train speed information from the flow rate control database.

[0028] The first control module is used to acquire the normal blowing and suction mode and the normal blowing and suction speed value, determine the direction of rotation and the actual speed value of the fan based on the normal blowing and suction mode and the normal blowing and suction speed value, and output the fan direction control command and the speed control command; wherein, the fan direction is determined according to the normal blowing and suction mode, the initial gas flow rate is obtained according to the relationship between speed and flow rate based on the normal blowing and suction speed value, the actual gas flow rate is obtained based on the initial gas flow rate, the system flow loss rate and the redundancy coefficient, and the actual speed value of the fan is obtained based on the relationship between the actual gas flow rate and the speed.

[0029] An air pump control module is used to acquire the fan rotation control command and speed control command, and based on the fan rotation control command and speed control command, adjust the fan rotation and speed of the air pump, and control the gas flow through the air pump and blow out or draw in through the air hole.

[0030] The gas supply control module is used to control the gas supply pipeline to supply gas to the air pump control module.

[0031] Furthermore, the train pneumatic drag reduction system also includes a flow valve speed control module;

[0032] The flow valve speed control module is used to control the flow valve installed near the wall of the vehicle body to regulate the gas flowing out from the air pump.

[0033] One embodiment of this application also provides a computer device, including a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of the train aerodynamic drag reduction method described in any of the above claims.

[0034] One embodiment of this application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the train aerodynamic drag reduction method described above.

[0035] In summary, compared with the prior art, the beneficial effects of the technical solution provided in this application include at least the following:

[0036] 1. By determining the turbulent flow field structure around the train, specific flow locations associated with aerodynamic drag reduction are identified. Different ranges of air-blowing and air-suction control zones are then established at these specific flow locations. A train aerodynamic numerical simulation model is used to analyze the drag reduction effects of normal air-blowing and normal air-suction modes within the air-blowing and air-suction control zones. Based on these drag reduction effects, an active drag reduction control zone is determined. Furthermore, different normal air-blowing and air-suction velocities can be set within the active drag reduction control zone to obtain the variation law of the train's aerodynamic drag reduction rate with air-blowing and air-suction velocity at different train operating speeds. This yields the normal air-blowing and air-suction modes and their corresponding normal air-blowing and air-suction velocity values ​​with drag reduction effects. A flow velocity control database is then established. Based on this database, active aerodynamic drag reduction control is implemented, thereby achieving precise aerodynamic drag reduction regulation at the required locations on high-speed trains.

[0037] 2. A two-stage control module is used to adjust the speed of the normal blowing and intake in two stages, which can achieve more precise aerodynamic drag reduction control of the train.

[0038] 3. The method of using train aerodynamic numerical simulation model analysis to determine the active drag reduction control area and obtain the normal blowing and suction mode and normal blowing and suction velocity value with drag reduction effect is not limited by experimental conditions, and the research cycle is short and the cost is low. Attached Figure Description

[0039] Figure 1 This is a schematic flowchart of a train aerodynamic drag reduction method provided in an embodiment of this application;

[0040] Figure 2 This is a schematic diagram of the first active drag reduction control region provided in an embodiment of this application;

[0041] Figure 3 This is a schematic diagram of the second active drag reduction control region provided in an embodiment of this application;

[0042] Figure 4 This is a schematic diagram of the third active drag reduction control region provided in an embodiment of this application;

[0043] Figure 5 This is a schematic diagram illustrating the variation of train aerodynamic drag reduction rate with air blowing and suction speed according to an embodiment of this application;

[0044] Figure 6 This is a schematic diagram of a train aerodynamic drag reduction system provided in one embodiment of this application. Detailed Implementation

[0045] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

[0046] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] Furthermore, the term "and / or" in this application is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this application, unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship.

[0048] In this application, the terms "first," "second," etc., are used to distinguish identical or similar items with essentially the same function. It should be understood that there is no logical or temporal dependency between "first," "second," and "nth," nor are there any restrictions on quantity or execution order.

[0049] The embodiments of this application will now be described in further detail with reference to the accompanying drawings.

[0050] Reference Figure 1 In one embodiment of this application, a simulation method for train aerodynamic drag reduction is provided. The main steps of the method are described as follows:

[0051] S10: Establish a numerical simulation model of the train's aerodynamic characteristics, use the numerical simulation model of the train's aerodynamic characteristics to determine the turbulent flow field structure around the train, and locate the special flow positions associated with aerodynamic drag reduction.

[0052] A numerical simulation model of the train's aerodynamic characteristics was established using computational fluid dynamics (CFD) software. Simulations were performed to determine the turbulent flow field structure around the train and to locate specific flow positions associated with aerodynamic drag reduction. Based on aerodynamic theory, a numerical simulation model of the train's aerodynamic characteristics was established using CFD software. Turbulence is a flow state of fluids. When the flow velocity is very low, the fluid flows in stratified layers without mixing; this state is called laminar flow, also known as steady flow or sheet flow. As the flow velocity gradually increases, the streamlines of the fluid begin to exhibit wavy oscillations, with the frequency and amplitude of the oscillations increasing with the flow velocity; this state is called transitional flow. When the flow velocity increases to a very high level, the streamlines are no longer clearly visible, and many small vortices form in the flow field. Laminar flow is disrupted, and there is not only sliding but also mixing between adjacent flow layers; this is when turbulence is formed.

[0053] In the embodiments of this application, the step of determining the turbulent flow field structure around the train using a numerical simulation model of train aerodynamic characteristics includes:

[0054] A realistic geometric model of the train structure was established using 3D software. The simulation model included the lead car, middle car, and tail car. Any 3D software such as CAD, CAM, or CAE could be used. CFD preprocessing software was used to establish the numerical computation domain and perform mesh generation. In computational fluid dynamics, a mesh is a collection of discrete points distributed in a fluid according to a certain pattern; the process of generating these nodes is called mesh generation. Mesh generation is the link between the geometric model and the numerical algorithm; the geometric model can only be numerically solved when it is divided into a standardized mesh. The denser the mesh, the more accurate the results, but the more time-consuming it is. The accuracy and efficiency of the numerical computation results mainly depend on the mesh and the strategy used during mesh generation. Any one of the following strategies—structured mesh, unstructured mesh, polyhedral mesh, or hybrid mesh—was used to mesh the realistic geometric model of the train structure. A structured mesh strategy was used when the train geometric model was relatively simple; when the train geometric model was complex, unstructured mesh, polyhedral mesh, or hybrid mesh strategies could be used. The area around the train at a distance of twice the train height and the wake region are areas of drastic flow field changes, requiring mesh refinement. The boundary layer mesh is crucial for solving wall flow; the boundary layer mesh should have at least 10 layers, with a mesh growth factor no greater than 1.2 and an aspect ratio of no more than 50 for the first layer. Three mesh densities—coarse, medium, and fine—need to be established, and mesh independence analysis should be performed.

[0055] Flow field control requires accurate simulation of the surrounding flow field structure and distribution characteristics, including precise simulation of flow separation and wake vortices. Therefore, an unsteady separated vortex turbulence model is adopted, with the normalized residual order of magnitude of the flow field parameters and the turbulence model parameters set to 10. -6 In the discrete terms, each term is selected with a precision of second order or higher to further improve the calculation accuracy.

[0056] Based on the relevant theoretical foundations of fluid mechanics and flow field visualization software, numerical simulation analysis was carried out on the actual geometric model of the train structure. Through data analysis and visualization analysis of the velocity and pressure fields around the train, the correlation between the change of air velocity around the train and the pressure on the train surface was determined, and the correspondence between the gas velocity around the train and the pressure on the train surface was obtained. The development law of the boundary layer on the train surface and the location of boundary layer separation were determined by the velocity distribution curve, revealing the generation mechanism and development law of the flow vortex around the train body.

[0057] Based on relevant fluid mechanics theories and flow field visualization software, numerical simulation analysis was conducted. Through data analysis and visualization analysis of the velocity and pressure fields around the train, the correlation between changes in air velocity around the train and the surface pressure of the train was determined, and the correspondence between gas velocity and surface pressure around the train was obtained. Furthermore, the development law of the boundary layer on the train surface and the location of boundary layer separation were determined by velocity distribution curves, revealing the generation mechanism and development law of flow vortices around the train body. By analyzing the correlation between the turbulent flow field structure and the aerodynamic drag of the train, the locations of boundary layer abrupt changes, flow separation points, flow reattachment points, and vortex shedding points in the turbulent flow were located. These locations are special flow locations associated with aerodynamic pressure drag.

[0058] S20: Set up blowing and suction control areas of different ranges at the special flow position, and analyze the drag reduction effect of the normal blowing and normal suction modes of the blowing and suction control areas on the numerical simulation model of the train aerodynamic characteristics. Determine the active drag reduction control area based on the drag reduction effect, and set air holes in the active drag reduction control area.

[0059] In step S10, different ranges of surface blowing and suction control zones are set at the specific flow position. These different ranges include: the area in front of the specific flow position, the area containing the specific flow position, and the area behind the specific flow position. The drag reduction effect of both normal blowing and normal suction modes is analyzed for the determined control zones. The areas with drag reduction effect are identified as active drag reduction control zones, and air vents are set in these active drag reduction control zones. Analysis has determined that the active drag reduction control zones with drag reduction effect include: a first active drag reduction control zone, a second active drag reduction control zone, and a third active drag reduction control zone. This accurately determines the location where the train needs aerodynamic drag reduction, improving the effectiveness of aerodynamic drag reduction through normal blowing and suction. Specifically, as shown... Figure 2 As shown, the first active drag reduction control area is the region in front of the streamlined train head at the transition position of the constant cross-section body; as Figure 3 As shown, the second active drag reduction control area is the region behind the transition point of the constant cross-section body at the streamlined rear; as Figure 4 As shown, the third active drag reduction control area is the area at the rear nose of the vehicle, including the location of the flow separation point.

[0060] Air holes are installed on the surface of the first, second, and third active drag reduction control areas of the train. The air holes are arranged at equal intervals. The size of the holes can be designed according to the specific dimensions of the train model, the main track routing, the chamfer size, strength requirements, and other constraints, but should not be too large to affect the overall shape and safety of the train.

[0061] S30: Set different normal blowing and suction speeds in the active drag reduction control area to obtain the variation law of train aerodynamic drag reduction rate with normal blowing and suction speed under different train running speeds, obtain normal blowing and suction mode with drag reduction effect and normal blowing and suction speed value, and establish a flow rate control database.

[0062] By setting different normal blowing or normal suction velocities in the active drag reduction control region, the variation law of train aerodynamic drag reduction rate with normal blowing and suction velocity at different train operating speeds is obtained. This yields the normal blowing and suction mode and normal blowing and suction velocity values ​​when drag reduction is achieved, and a flow velocity control database is established accordingly. For example... Figure 5 As shown, the aerodynamic drag reduction ratio of a certain type of train varies with the blowing and suction speed, where v represents the blowing and suction speed value and V represents the train's running speed. According to this variation law, at the current train speed, the blowing and suction mode with drag reduction effect is normal blowing, and the drag reduction ratio increases with the increase of the blowing speed. When v / V is 0.5, that is, when the normal blowing speed value is 0.5 times the train's running speed, the aerodynamic drag reduction ratio is the largest.

[0063] S40: Based on the flow rate control database, perform active aerodynamic drag reduction control.

[0064] Based on the flow rate control database, select the normal blowing and suction modes and blowing and suction speed values ​​with drag reduction effect in each active drag reduction control region at the current vehicle speed, and perform active aerodynamic drag reduction control.

[0065] In one exemplary embodiment, the steps of performing active drag reduction control based on a flow rate control database include:

[0066] Based on the drag-reducing normal-flow / intake mode and the normal-flow / intake velocity value, the fan's direction of rotation and actual speed are determined, and fan direction and speed control commands are output. Specifically, the fan direction of rotation is determined according to the normal-flow / intake mode: if it's normal-flow, a command to rotate the fan clockwise is output; if it's normal-intake, a command to rotate the fan counterclockwise is output. Based on the normal-flow / intake velocity value, the initial gas flow rate is obtained according to the velocity-flow-flow relationship. Based on the initial gas flow rate, the system flow loss rate, and the redundancy coefficient relationship, the actual gas flow rate is obtained. Based on the actual gas flow rate and speed relationship, the actual fan speed value is obtained.

[0067] The relationship between velocity and flow rate is: Q1 = S 气孔 ×N 气孔 ×v,

[0068] Q1 represents the initial fan flow rate, S 气孔 N represents the effective area of ​​a single pore. 气孔 This indicates the number of air holes on the vehicle body surface, and v represents the blowing and suction speed value.

[0069] The relationship between the initial gas flow rate, system flow loss rate, and redundancy coefficient is: Q2 = Q1 / ×C / η.

[0070] η represents the system flow loss rate, and C (C>1) represents the redundancy coefficient;

[0071] The actual gas flow rate and rotational speed relationship is as follows:

[0072] n represents the actual rotational speed, n0 represents the rated rotational speed, and Q0 represents the flow rate at the rated rotational speed.

[0073] Based on the fan steering control command and speed control command, the gas in the gas delivery pipeline of the gas delivery control module is controlled to flow through the air pump of the first control module and be blown out or drawn in through the air hole.

[0074] In this embodiment, the active pneumatic drag reduction control step based on the flow rate control database further includes adjusting the gas flowing from the air pump via a flow valve located near the vehicle body wall. Specifically, based on the actual gas flow rate, the valve core of the flow valve controls the valve opening size to perform secondary precise regulation of the gas flowing from the air pump, and the gas is then blown out or drawn in through the air hole. This two-stage regulation via the air pump and flow valve makes the gas flow rate control more precise, achieving a better pneumatic drag reduction effect.

[0075] like Figure 6 As shown in the figure, this application embodiment also provides a train aerodynamic drag reduction system, which includes a flow rate control module, a first regulation module, an air pump control module, an air delivery control module, and a flow valve speed regulation module.

[0076] The flow rate control module is used to receive the current train speed information and retrieve the normal blowing and suction modes and normal blowing and suction speed values ​​corresponding to each active drag reduction control area under the current train speed information from the flow rate control database.

[0077] The first control module is used to receive the normal blowing and suction mode with drag reduction effect and the normal blowing and suction speed value, determine the direction of rotation and actual speed value of the fan, and output the fan direction control command and speed control command. Specifically, the fan direction is determined based on the normal blowing and suction mode, the initial gas flow rate is obtained based on the normal blowing and suction speed value and the relationship between speed and flow rate, the actual gas flow rate is obtained further based on the relationship between the initial gas flow rate, the system flow loss rate and the redundancy coefficient, and the actual speed value of the fan is obtained based on the relationship between the actual gas flow rate and the speed.

[0078] The air pump control module is used to receive fan direction control commands and speed control commands, control the flow of gas through the air pump, and blow it out or draw it in through the air vents.

[0079] The air pump control module is used to control the flow of gas through the air pump, which passes through a flow valve located near the wall of the vehicle body and is either blown out or drawn in through the air hole.

[0080] The gas delivery control module is used to control the flow of gas through the gas delivery pipeline via the air pump and flow valve, and to blow or draw in the gas through the air vent.

[0081] This drag reduction system employs a two-stage speed regulation system using an air pump and a flow valve. The air pump performs the first-stage speed regulation, while the flow valve performs the second-stage fine adjustment, enabling precise control of the blowing and suction speeds and achieving more accurate aerodynamic drag reduction control for the train.

[0082] The flow rate control module obtains the current vehicle speed V from its flow rate control database center, retrieves the blowing and suction modes and blowing and suction speed values ​​v with drag reduction effects in each active drag reduction control area at the current vehicle speed; the flow rate control module transmits the normal blowing and suction modes and normal blowing and suction speed values ​​v to the first control module; the first control module obtains the initial fan flow rate Q1 according to the speed-flow relationship, and obtains the actual fan flow rate Q2 according to the system flow loss rate η and redundancy coefficient C (C>1), and obtains the actual speed value n according to the fan flow rate-speed relationship, and outputs the fan direction control command and speed control command; the air pump control module adjusts the fan direction and speed of the air pump according to the fan direction control command and speed control command, so that the gas in the air delivery pipeline flows through the air pump, and then undergoes secondary fine adjustment through the flow valve set near the wall of the vehicle body, and is blown out or sucked in through the air hole.

[0083] Where Q1 = S_pores × N_pores × v, where S_pores represents the effective area of ​​a single pore and N_pores represents the number of pores on the vehicle body surface; Q2 = Q1 / ×C / η; Where n0 represents the rated speed and Q0 is the flow rate at the rated speed.

[0084] Specifically, a numerical simulation model of train aerodynamic characteristics was established to determine the turbulent flow field structure around the train and locate special flow positions associated with aerodynamic drag reduction. Different ranges of blowing and suction control zones were set at these special flow positions, and the drag reduction effects of normal blowing and normal suction modes within the blowing and suction control zones were analyzed on the numerical simulation model. Based on the drag reduction effects, an active drag reduction control zone was determined, and air vents were set within this zone. Different normal blowing and suction velocities were set within the active drag reduction control zone to obtain the variation law of the train's aerodynamic drag reduction rate with the normal blowing and suction velocity at different train operating speeds. This yielded the normal blowing and suction modes with drag reduction effects and their corresponding normal blowing and suction velocity values, and a flow velocity control database was established.

[0085] In one embodiment of this application, an electronic device is provided, which may be a server. The electronic device includes a processor, a memory, and a network interface connected via a system bus. The processor of the electronic device provides computing and control capabilities. The memory of the electronic device can be implemented using any type of volatile or non-volatile storage device or a combination thereof. Volatile or non-volatile storage devices include, but are not limited to: magnetic disks, optical disks, EEPROM (Electrically Erasable Programmable Read Only Memory), EPROM (Erasable Programmable Read Only Memory), SRAM (Static Random Access Memory), ROM (Read-Only Memory), magnetic storage, flash memory, and PROM (Programmable Read-Only Memory). The memory of the electronic device provides an environment for the operation of the operating system and computer programs stored within it. The network interface of the electronic device is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements the steps of the train aerodynamic drag reduction method described in the above embodiments.

[0086] In one embodiment of this application, a computer-readable storage medium is provided, which stores a computer program. When executed by a processor, the computer program implements the steps of the train aerodynamic drag reduction method described in the above embodiment. The computer-readable storage medium includes ROM (Read-Only Memory), RAM (Random-Access Memory), CD-ROM (Compact Disc Read-Only Memory), magnetic disk, floppy disk, etc.

[0087] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the system described in this application can be divided into different functional units or modules to complete all or part of the functions described above.

Claims

1. A method for reducing aerodynamic drag on trains, characterized in that, The method includes: A numerical simulation model of train aerodynamic characteristics is established. The turbulent flow field structure around the train is determined using the numerical simulation model of train aerodynamic characteristics, and the special flow positions associated with aerodynamic drag reduction are located. Different ranges of air blowing and suction control zones are set at the special flow position, and the drag reduction effect of the air blowing and suction control zones in the normal air blowing and normal air suction modes is analyzed on the numerical simulation model of the train aerodynamic characteristics. Based on the drag reduction effect, the active drag reduction control zone is determined, and air holes are set in the active drag reduction control zone. Different normal blowing and suction speeds are set in the active drag reduction control area to obtain the variation law of train aerodynamic drag reduction rate with normal blowing and suction speed at different train running speeds, thereby obtaining the normal blowing and suction mode with drag reduction effect and the normal blowing and suction speed value, and establishing a flow rate control database. Based on the flow rate control database, active aerodynamic drag reduction control is performed. Specifically, the steps of performing active aerodynamic drag reduction control based on the flow rate control database include: receiving current train speed information, retrieving from the flow rate control database the normal blowing / suction mode and normal blowing / suction velocity value corresponding to the active drag reduction control area under the current train speed information; determining the fan's direction of rotation and actual speed value based on the normal blowing / suction mode and normal blowing / suction velocity value, and outputting fan direction control commands and speed control commands; wherein, the fan direction of rotation is determined according to the normal blowing / suction mode, the initial gas flow rate is obtained based on the normal blowing / suction velocity value according to the speed-flow relationship, the actual gas flow rate is obtained based on the initial gas flow rate, the system flow loss rate, and the redundancy coefficient, and the actual speed value of the fan is obtained based on the actual gas flow rate and speed relationship; and controlling the gas in the gas delivery pipeline to flow through the air pump and be blown out or drawn in through the air vents based on the fan direction control commands and speed control commands.

2. The train aerodynamic drag reduction method according to claim 1, characterized in that, Before being blown out or inhaled through the air hole, the method further includes: The flow rate valve located near the wall of the vehicle body regulates the flow of gas through the air pump.

3. The train aerodynamic drag reduction method according to claim 1, characterized in that, The steps for determining the turbulent flow field structure around the train using the numerical simulation model of the train's aerodynamic characteristics include: A realistic geometric model of the train structure was created using 3D software. A numerical computation region is established in the actual geometric model of the train structure. The actual geometric model of the train structure is meshed, and the boundary conditions and turbulence model of the actual geometric model of the train structure are set. Numerical simulation and visualization analysis of the velocity and pressure fields on the train surface are performed based on the actual geometric model of the train structure. The relationship between the change in gas velocity on the train surface and the pressure on the train surface was obtained, and the development law of the boundary layer on the train surface and the location of boundary layer separation were determined by the velocity distribution curve.

4. The train aerodynamic drag reduction method according to claim 3, characterized in that, The step of meshing the actual geometric model of the train includes: The actual structural geometric model of the train is divided using a structured mesh strategy, an unstructured mesh strategy, a polyhedral mesh strategy, or a hybrid mesh strategy.

5. The train aerodynamic drag reduction method according to claim 4, characterized in that, The step of determining the turbulent flow field structure around the train using the numerical simulation model of the train's aerodynamic characteristics further includes: The normalized residual order of magnitude of the flow field parameters of the actual train structural geometry model and the normalized residual order of magnitude of the turbulence model parameters are set to 10. -6 Each term in the discrete term is selected with a precision of second order or higher.

6. The train aerodynamic drag reduction method according to claim 1, characterized in that, The specific flow locations associated with aerodynamic drag reduction include: boundary layer abrupt change sites, flow separation sites, flow reattachment sites, and vortex shedding sites.

7. A train aerodynamic drag reduction system, applied to the train aerodynamic drag reduction method of claim 1, characterized in that, The train aerodynamic drag reduction system includes a flow rate control module, a first regulation module, an air pump control module, and an air delivery control module. The flow rate control module is used to receive current train speed information and retrieve, from the flow rate control database, the normal blowing / inhalation mode and normal blowing / inhalation speed value corresponding to the active drag reduction control area under the current train speed information; specifically, the flow rate control module is also used to receive current train speed information and retrieve, from the flow rate control database, the normal blowing / inhalation mode and normal blowing / inhalation speed value corresponding to the active drag reduction control area under the current train speed information; based on the normal blowing / inhalation mode and normal blowing / inhalation speed value, the flow rate control module further retrieves the drag reduction mode and normal blowing / inhalation speed value. The blowing and suction speed values ​​determine the fan's direction of rotation and actual speed, and output fan direction control commands and speed control commands. Specifically, the fan direction is determined based on the normal blowing and suction mode; the initial gas flow rate is obtained based on the normal blowing and suction speed value and the speed-flow relationship; the actual gas flow rate is obtained based on the initial gas flow rate, system flow loss rate, and redundancy coefficient; and the actual fan speed is obtained based on the actual gas flow rate and speed-flow relationship. Based on the fan direction control commands and speed control commands, the gas in the gas delivery pipeline is controlled to flow through the air pump and be blown out or drawn in through the air vents. The first control module is used to acquire the normal blowing and suction mode and the normal blowing and suction speed value, determine the direction of rotation and the actual speed value of the fan based on the normal blowing and suction mode and the normal blowing and suction speed value, and output the fan direction control command and the speed control command; wherein, the fan direction is determined according to the normal blowing and suction mode, the initial gas flow rate is obtained according to the relationship between speed and flow rate based on the normal blowing and suction speed value, the actual gas flow rate is obtained based on the initial gas flow rate, the system flow loss rate and the redundancy coefficient, and the actual speed value of the fan is obtained based on the relationship between the actual gas flow rate and the speed. An air pump control module is used to acquire the fan rotation control command and speed control command, and based on the fan rotation control command and speed control command, adjust the fan rotation and speed of the air pump, and control the gas flow through the air pump and blow out or draw in through the air hole. The gas supply control module is used to control the gas supply pipeline to supply gas to the air pump control module.

8. A train aerodynamic drag reduction system according to claim 7, characterized in that, The train pneumatic drag reduction system also includes a flow valve speed control module; The flow valve speed control module is used to regulate the gas flowing through the air pump via a flow valve located near the wall of the vehicle body.

9. A computer device, characterized in that, The system includes a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of the train aerodynamic drag reduction method according to any one of claims 1 to 6.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the train aerodynamic drag reduction method according to any one of claims 1 to 6.

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