Skin panel and rail vehicle

Abstract

The present disclosure provides a skin outer plate and a rail vehicle. The skin outer plate is arranged on at least a part of the surface of the rail vehicle, and comprises a curved body part, the shape of the body part is configured to match the contour of the surface of the rail vehicle to adhere to the surface of the rail vehicle, and a plurality of pits arranged in an array are formed along the outer surface of the body part to the direction perpendicular to the outer surface; wherein the transverse spacing between two adjacent pits along the vehicle width direction of the rail vehicle is 2-4 times the maximum size of the pit, and the longitudinal spacing between two adjacent pits along the vehicle length direction of the rail vehicle is 8-10 times the maximum size, so as to reduce the air resistance of the rail vehicle during driving.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of rail vehicles, and more particularly, to a skin outer plate and a rail vehicle. BACKGROUND

[0002] Aerodynamic drag reduction is one of the main directions of high-speed train aerodynamic research. Traditional aerodynamic drag reduction mainly focuses on optimizing the train shape. The methods commonly used for train aerodynamic shape optimization mostly revolve around macro-structures and large sizes, such as lengthening the length of the streamlined head, reducing the train section, making the head sharp, setting a platform under the pantograph, and increasing the coverage of the bogie area. However, from the context, process, and results of train aerodynamic design development, the gains brought by these methods are close to the limit due to engineering practicality and train operation requirements. SUMMARY

[0003] Therefore, the present disclosure provides a skin outer plate and a rail vehicle, which can achieve aerodynamic drag reduction.

[0004] As an aspect of an embodiment of the present disclosure, a skin outer plate is provided, which is installed on at least a part of the surface of the rail vehicle. The skin outer plate includes a curved body portion, the shape of the body portion is configured to match the contour of the surface of the rail vehicle to adhere to the surface of the rail vehicle, and a plurality of pits arranged in an array are formed along the outer surface of the body portion to the direction perpendicular to the outer surface. Wherein, the transverse spacing between two adjacent pits along the vehicle width direction of the rail vehicle is 2-4 times the maximum size of the pit, and the longitudinal spacing between two adjacent pits along the vehicle length direction of the rail vehicle is 8-10 times the maximum size, so as to reduce the air resistance of the rail vehicle during driving.

[0005] According to an embodiment of the present disclosure, the skin outer plate further includes a plurality of support members, each of which extends from the inner surface of the body portion towards the surface of the rail vehicle, so as to form an accommodation space between the body portion and the support member to accommodate the pits arranged in a row or a column.

[0006] According to an embodiment of the present disclosure, each of the support members includes two mounting portions and a connecting portion. The two mounting portions are mounted on the inner surface of the body portion and located on both sides of the pits arranged in a row or a column. The connecting portion is integrally connected between the two mounting portions and curved away from the body portion to form the accommodation space.

[0007] According to an embodiment of the present disclosure, the periphery of the pit is smoothly connected with the body portion through a transition arc, so as to reduce the stress between the body portion and each of the pits.

[0008] According to an embodiment of the present disclosure, the depth of the concave pits is equal to half of the maximum dimension, and the maximum dimension ranges from 8 to 48 mm.

[0009] According to an embodiment of the present disclosure, the skin outer plate is arranged on at least one of the streamlined area on the top of the head car and the tail car of the rail vehicle and the top of the intermediate car.

[0010] According to an embodiment of the present disclosure, the skin outer plate is arranged on 30-80% of the streamlined area on the top of the head car and the tail car of the rail vehicle and on the linear area on the top of the head car, the tail car and the intermediate car.

[0011] According to an embodiment of the present disclosure, the cross section of the concave pit in the depth direction can be any one of a semicircle, a cone and a polygon.

[0012] As another aspect of an embodiment of the present disclosure, a rail vehicle is provided, including a head car, a tail car, an intermediate car and any one of the skin outer plates described above. The intermediate car is connected between the head car and the tail car, and any one of the skin outer plates described above is mounted on the surface of at least one of the head car, the tail car and the intermediate car to reduce the air resistance of the rail vehicle during running of the rail vehicle.

[0013] According to an embodiment of the present disclosure, a plurality of the skin outer plates are welded on the surface of at least one of the head car, the tail car and the intermediate car through a plate beam.

[0014] According to the skin outer plate of an embodiment of the present disclosure, the concave pits are arranged in an array by being recessed inward on the surface of the body part, and the transverse spacing between two adjacent concave pits in the vehicle width direction of the rail vehicle is 2-4 times the maximum dimension of the concave pit, and the longitudinal spacing between two adjacent concave pits in the vehicle length direction of the rail vehicle is 8-10 times the maximum dimension. In combination with the actual structure of the aluminum alloy car body or the composite material car body of the rail vehicle, the concave pit structure is arranged on the skin surface, and by reasonably adjusting and matching the maximum dimension, the depth, the distribution area, the transverse spacing and the longitudinal spacing of the concave pit, the differential pressure resistance can be reduced, the aerodynamic drag reduction can be realized, and the energy consumption index can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0015] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure taken in conjunction with the accompanying drawings, in which:

[0016] Figure 1 A side view of a rail vehicle according to an embodiment of the present disclosure is schematically shown;

[0017] Figure 2 A perspective view of a skin outer plate according to an embodiment of the present disclosure is schematically shown from one viewing angle.

[0018] Figure 3 A perspective view schematically illustrating another view of the skin outer plate according to an embodiment of the present disclosure is shown;

[0019] Figure 4 A partial cross-sectional view schematically illustrating the skin outer plate according to an embodiment of the present disclosure is shown;

[0020] Figure 5 A perspective view schematically illustrating a head car of a rail vehicle according to an embodiment of the present disclosure is shown;

[0021] Figure 6 A side view schematically illustrating the head car of the rail vehicle according to an embodiment of the present disclosure is shown;

[0022] Figure 7 A perspective view schematically illustrating a middle car of a rail vehicle according to an embodiment of the present disclosure is shown;

[0023] Figure 8 A schematic view of an axle system of a test model car body according to an embodiment of the present disclosure is shown;

[0024] Figure 9 A head car drag coefficient repeatability test result according to an embodiment of the present disclosure is shown;

[0025] Figure 10 A middle car drag coefficient repeatability test result according to an embodiment of the present disclosure is shown;

[0026] Figure 11 A tail car drag coefficient repeatability test result according to an embodiment of the present disclosure is shown;

[0027] Figure 12 A head car drag coefficient of different pit schemes according to an embodiment of the present disclosure is shown;

[0028] Figure 13 A middle car drag coefficient of different pit schemes according to an embodiment of the present disclosure is shown;

[0029] Figure 14 A tail car drag coefficient of different pit schemes according to an embodiment of the present disclosure is shown;

[0030] Figure 15 A column chart showing the effect of pit radius 0.6-1.0mm, transverse spacing 6mm, and longitudinal spacing 18mm on drag reduction according to an embodiment of the present disclosure is shown;

[0031] Figure 16A bar chart showing the influence of the pit radius 1.0-3.0 mm, the lateral spacing 10 mm, and the longitudinal spacing 30 mm on the drag reduction effect according to an embodiment of the present disclosure is schematically shown;

[0032] Figure 17 A bar chart showing the influence of the pit radius on the aerodynamic drag according to an embodiment of the present disclosure is schematically shown;

[0033] Figure 18 A bar chart showing the influence of the lateral spacing on the aerodynamic drag according to an embodiment of the present disclosure is schematically shown; and

[0034] Figure 19 A bar chart showing the influence of the longitudinal spacing on the aerodynamic drag according to an embodiment of the present disclosure is schematically shown.

[0035] BRIEF DESCRIPTION OF DRAWINGS

[0036] 1 - skin outer plate

[0037] 11 - body portion

[0038] 12 - pit

[0039] 13 - support

[0040] 131 - mounting portion

[0041] 132 - connecting portion

[0042] 14 - transition arc

[0043] 2 - rail vehicle

[0044] 21 - head car

[0045] 22 - tail car

[0046] 23 - intermediate car DETAILED DESCRIPTION

[0047] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood, however, that the description is merely exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description of the embodiments of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. However, it would be apparent to those skilled in the art that the embodiments of the present disclosure can be practiced without these specific details. In other instances, well-known structures and techniques have not been described in detail in order to avoid obscuring aspects of the present disclosure.

[0048] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the term "includes" and tautological equivalents thereof, means that the named feature is present, but does not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or the like.

[0049] All terms used herein including technical and scientific terms have the meanings commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein are defined as having a meaning that is consistent with the context of the specification in which the terms are utilized and the terms should not be interpreted in an idealized or overly formal sense.

[0050] In situations where similar terminology is used for similar items, it is to be understood that there is no intention to limit such terms to the specific examples described unless otherwise explicitly stated. In using similar expressions such as "at least one of A, B, and C," it is generally intended that the conjunctive phrase, "at least one of A, B, and C," be interpreted to mean that A alone, B alone, C alone, or any combination of the items in the set of A, B, and C are possible (e.g., "a system having at least one of A, B, and C" would include, but not be limited to, a system having A alone, a system having B alone, a system having C alone, a system having both A and B, a system having both A and C, a system having both B and C, and / or a system having A, B, and C).

[0051] Figure 1 A side view of a rail vehicle according to an embodiment of the present disclosure is schematically shown, Figure 2 A perspective view of one view of a skin panel according to an embodiment of the present disclosure is schematically shown.

[0052] As an aspect of the embodiments of the present disclosure, a skin panel 1 is provided. As shown, Figure 1 The skin panel 1 is installed on at least a portion of a surface of a rail vehicle 2, as shown, Figure 2 The skin panel 1 comprises a curved body portion 11, the shape of the body portion 11 is configured to match the profile of the surface of the rail vehicle 2 to attach to the surface of the rail vehicle 2, a plurality of pits 12 arranged in an array are formed along the outer surface of the body portion 11 to recess in a direction perpendicular to the outer surface. Wherein, the lateral spacing (B in Figure 2 ) between two adjacent pits along the vehicle width direction of the rail vehicle 2 is 2-4 times of the maximum dimension of the pit, the longitudinal spacing (A in Figure 2 ) between two adjacent pits along the vehicle length direction of the rail vehicle 2 is 8-10 times of the maximum dimension, when fluid flows through the pit area, the vortex system of the fluid will rapidly increase the turbulent intensity, so that the fluid obtains greater kinetic energy to delay flow separation and reattach to the wall surface of the rail vehicle 2, which can improve the flow field behind the area, reduce vortex generation, and make the wake flow of the pit area more smooth, so as to achieve the purpose of reducing the air resistance of the rail vehicle 2 during driving.

[0053] According to the skin outer plate of the embodiment of the present disclosure, by forming the array-arranged pits in the surface of the body portion inwardly recessed, and making the transverse spacing between two pits adjacent in the vehicle width direction of the rail vehicle 2-4 times the maximum size of the pit, and the longitudinal spacing between two pits adjacent in the vehicle length direction of the rail vehicle 8-10 times the maximum size of the pit, in combination with the actual structure of the aluminum alloy car body or the composite material car body of the rail vehicle, the pit structure is arranged on the surface of the skin, and by reasonably adjusting and matching the maximum size, the depth, the distribution area, the transverse spacing and the longitudinal spacing of the pit, the pressure difference resistance can be reduced, the aerodynamic drag reduction can be realized, and the energy consumption index can be reduced.

[0054] In an illustrative embodiment, the transverse spacing is any one of 2 times, 2.5 times, 3 times, 3.2 times, 3.5 times and 4 times the maximum size of the pit.

[0055] In an illustrative embodiment, the longitudinal spacing is any one of 8 times, 8.5 times, 9 times, 9.5 times, 9.7 times and 10 times the maximum size of the pit.

[0056] In an illustrative embodiment, the skin outer plate 1 is installed on the outer plate of the cab of the rail vehicle 2.

[0057] In the process of implementing the present disclosure, it is found that due to the existence of the depth size of the pit, a simple sheet material cannot meet the pit modeling needs, such as blindly increasing the thickness of the plate, which will cause the problem of weight increase of the structure, is not conducive to the lightweight design of the structure, and is easy to bring design redundancy.

[0058] Figure 3 A perspective view of another view of the skin outer plate according to the embodiment of the present disclosure is schematically shown.

[0059] According to the embodiment of the present disclosure, as shown in Figure 2 and Figure 3 The skin outer plate 1 further comprises a plurality of support pieces 13. Each support piece 13 extends from the inner surface of the body portion 11 towards the surface of the rail vehicle, so that the body portion 11 and the support piece 13 form an accommodation space for accommodating the pits arranged in rows or columns.

[0060] In an illustrative embodiment, according to the specific area of the pit distribution, a ridge-shaped support piece is arranged on the inner surface of the body portion corresponding to the pit distribution position. The existence of the support piece is equivalent to thickening the thickness of the body portion in the region where the pit is located, so that the deformation amount of the body portion is reduced, and the vibration and noise reduction effect is achieved. For the positions without pits, the thickness of the plate is still maintained as the thickness of the sheet, which has the effect of less weight increase compared with the original sheet, does not bring a large amount of weight increase, and realizes the lightweight design.

[0061] According to the embodiment of the present disclosure, as shown in Figure 3As shown, each support piece 13 includes two mounting portions 131 and a connecting portion 132. The two mounting portions 131 are mounted on the inner surface of the body portion 11 and are located on both sides of the row or column of pits. The connecting portion 132 is integrally connected between the two mounting portions 131 and is bent away from the body portion to form an accommodation space.

[0062] According to the embodiments of the present disclosure, after the pits are formed on the body portion, the stiffness characteristics of the body portion are undoubtedly increased from the anti-vibration principle, which plays a role in anti-vibration and deformation prevention, and improves the sound insulation characteristics of the body portion. The stiffness of the skin outer plate is also improved and the noise reduction is also positively affected. The skin outer plate provided by the present disclosure is thinner than the original single plate sheet outer plate, which reduces the deformation amount under the same external load and can reduce the deformation amount by 41.12%.

[0063] According to the embodiments of the present disclosure, the support piece can be mounted (for example, by welding) on the inner surface of the body portion through the mounting portion.

[0064] In an illustrative embodiment, the skin outer plate can be made of metal materials such as stainless steel, iron, etc. In the manufacturing process, machining forming or superplastic forming can be used to realize product manufacturing. For the skin outer plate with a large area of pits, block forming and then welding can be used. The overall structure design is more flexible and variable, and is suitable for various rail vehicles.

[0065] In another illustrative embodiment, the skin outer plate can be made of composite materials. In the manufacturing process, mold forming process can be used. For the pits, secondary forming can be used. For the large-area skin outer plate, block forming and then secondary gluing can also be used. The overall structure design and mold design are flexible and variable, and can be produced in modules.

[0066] In the process of implementing the present disclosure, it is found that on the outer side of the skin outer plate, paint spraying is generally needed to improve the corrosion resistance of the skin outer plate and to improve the service life of the skin outer plate. However, considering the actual process performance of forming and the spraying effect of the product, the outer edge of the pit is a difficult point in processing and a position where the paint film adhesion is weak in spraying. There are problems such as processing difficulty, stress concentration, poor paint film adhesion, and damaged paint.

[0067] Figure 4 An illustrative partial cross-sectional view of a skin outer plate according to an embodiment of the present disclosure is shown.

[0068] According to the embodiments of the present disclosure, as shown in Figure 4 The periphery of the pit 12 is smoothly connected to the body portion 11 through a transition arc 14 to reduce the stress between the body portion 11 and each pit 12 and improve the adhesion of the paint film in the case of paint coating.

[0069] According to the embodiment of the present disclosure, the circumferential edge of each pit 12 is smoothly connected to the body part 11 by a transition arc 14 with a radius R1, which can avoid stress concentration and enhance the paint film thickness and adhesion at this position without affecting the aerodynamic drag reduction effect. The radius R1 of the transition arc can be smaller than the depth D of the pit.

[0070] In an exemplary embodiment, as shown in Figure 4 , the thickness of the body part is t, and the thickness of the pit and the non-pit position is the same (both t) to ensure the structural strength of the pit.

[0071] According to the embodiment of the present disclosure, the depth D of the pit is equal to half of the maximum dimension, and the maximum dimension is in the range of 8-48 mm.

[0072] In an exemplary embodiment, the cross section of the pit in the depth direction is semicircular, the maximum dimension of the pit is the diameter, and the depth D of the pit is the radius R.

[0073] According to the embodiment of the present disclosure, the pit is a microstructure relative to the car body of the railway vehicle, which does not affect and damage the appearance and modeling of the railway vehicle. For the skin outer plate, the support inside the skin plays the effect of the plate beam structure, which can provide a containing space for the pit and avoid the direct contact between the pit bottom and the car body of the railway vehicle, thereby avoiding the direct stress of the pit. The size of the support is relatively small compared to the plate beam, which also plays a weight reduction effect. Meanwhile, the relatively small internal structure also occupies a small internal space of the railway vehicle.

[0074] Figure 5 An exemplary perspective view of a head car of a railway vehicle according to an embodiment of the present disclosure is shown.

[0075] According to the embodiment of the present disclosure, as shown in Figure 5 , the skin outer plate 1 is arranged on at least one of the streamlined area on the top of the head car 21 and the tail car 22 and the top of the middle car 23 of the railway vehicle 2.

[0076] It can be understood that the head car and the tail car are relative to the running direction of the railway vehicle, and the head car is located at the front end of the running direction, and the tail car is located at the rear end of the running direction.

[0077] In an exemplary embodiment, as shown in Figure 5 , the skin outer plate is arranged on the streamlined area on the top of the head car of the railway vehicle.

[0078] Figure 6 An exemplary side view of a head car of a railway vehicle according to an embodiment of the present disclosure is shown, Figure 7A perspective view of a middle car of a rail vehicle according to an embodiment of the present disclosure is schematically shown.

[0079] According to an embodiment of the present disclosure, as shown in Figure 6 and Figure 7 , the skin outer plate is arranged on 30-80% of the streamlined area of the top of the head car and the tail car of the rail vehicle, and on the linear area of the top of the head car, the tail car and the middle car.

[0080] According to an embodiment of the present disclosure, as shown in Figure 5 and Figure 6 , the length of the streamlined area of the top of the head car of the rail vehicle is L, and the skin outer plate can be arranged on 90% (0.9L) of the streamlined area of the top of the head car of the rail vehicle, preferably 30-80%, such as 0.6L, 0.5L or 0.3L. Figure 6

[0081] According to an embodiment of the present disclosure, the skin outer plate can be arranged on the linear area of the top of the middle car at intervals to avoid components such as air conditioners located on the roof.

[0082] According to an embodiment of the present disclosure, the cross section of the dimple in the depth direction can be any one of a semicircle, a cone and a polygon. For example, it can be half of a rectangle or a regular polygon.

[0083] The skin outer plate provided by the embodiments of the present disclosure is an outer plate structure with a plurality of dimples arranged in an array, which has the advantages of reducing drag, sound insulation, improving stiffness and deformation resistance, etc. Meanwhile, by reasonably arranging the dimples and the support pieces, the weight is effectively controlled without occupying the interior space of the vehicle. After the dimple structure is arranged on the body part, the aerodynamic drag of the rail vehicle can be reduced to achieve drag reduction optimization. Meanwhile, the skin outer plate provided by the embodiments of the present disclosure also has the advantages of sound insulation, high stiffness and high deformation resistance, etc. Compared with the original outer plate structure, the deformation resistance is improved by more than 40%. The transition circular arc with a radius of R1 is used to smoothly connect each dimple with the body part, which can ensure the effective adhesion of paint. After the sample corrosion and impact resistance test, no corrosion or damage of the paint occurs.

[0084] According to an embodiment of the present disclosure, by arranging hemispherical dimples with a radius of R and a depth of D in a transverse interval S and a longitudinal interval L on different areas of the surface of the rail vehicle, preferably at the roof position, according to the range size, position and specific structure of the rail vehicle, the transverse interval S of the dimple, the longitudinal interval L of the dimple, the radius R of the dimple and the depth D of the dimple are matched, and the combination of multiple parameters can make this technology applicable to trains with different shapes, structures and speed levels, and expand the applicability of this technology.

[0085] ​According to the embodiment of the present disclosure, the transverse spacing, longitudinal spacing, pit radius and pit depth of the pits are designed in combination with the actual structure of the train, manufacturing precision and application status. For example, the pit depth D can be in the range of 4-24 mm, and the pit radius R can be in the range of 4-24 mm.

[0086] According to the embodiment of the present disclosure, the five parameters of pit coverage area A, pit transverse spacing S, pit longitudinal spacing L, pit radius R and pit depth D can be evaluated and verified according to wind tunnel test or simulation calculation in combination with basic aerodynamics theory. The specific evaluation target value of the aerodynamic drag coefficient can be calculated according to formula (1):

[0087] (1);

[0088] wherein, is the aerodynamic drag coefficient, is the aerodynamic drag obtained by test or calculation, is the air flow density, is the flow velocity, is the longitudinal section area of the rail vehicle.

[0089] In the wind tunnel test, the air flow density can be obtained by calculating the formula according to the monitoring of the atmospheric pressure, humidity, temperature and other environmental parameters in the wind tunnel test section. In the simulation calculation, the air flow density can be directly defined. In the wind tunnel test, the flow velocity of the present test is determined by defining the blowing speed pressure or blowing speed of the defined sub-working condition; in the calculation, the air flow velocity can be defined by directly defining the speed value of the speed inlet.

[0090] According to the embodiment of the present disclosure, by arranging pits in a specific area on the surface of the rail vehicle, the pressure difference resistance term in the aerodynamic drag of the rail vehicle can be reduced, and the whole vehicle drag reduction is realized.

[0091] According to the embodiment of the present disclosure, by combining the pit coverage area A, pit transverse spacing S, pit longitudinal spacing L, pit radius R and pit depth D, the technology can be applied to rail vehicles (or trains) of various shapes, sections and speed levels.

[0092] According to the embodiment of the present disclosure, the pit layout is only on the surface of the rail vehicle, and has no influence on the internal structure, space occupation and external device use of the rail vehicle, so that the influence of the drag reduction technology and structure on the design and construction of each component of the rail vehicle is minimized.

[0093] As another aspect of the embodiment of the present disclosure, a rail vehicle 2 is provided, as shown in Figure 1 , Figures 5 to 7As shown, the rail vehicle 2 includes a head car 21, a tail car 22, a middle car 23, and a plurality of any one of the skin outer plates 1. The middle car 23 is connected between the head car 21 and the tail car 22, and the plurality of any one of the skin outer plates 1 is installed on the surface of at least one of the head car 21, the tail car 22, and the middle car 23 to reduce the air resistance of the rail vehicle 2 during travel of the rail vehicle 2.

[0094] According to the embodiment of the present disclosure, the dimple structure is only arranged on the skin outer plate of the surface of the rail vehicle, without occupying the internal space of the rail vehicle, without blocking the external facilities, and without changing the overall appearance of the rail vehicle. The embodiment of the present disclosure not only ensures the aesthetic appearance of the shape, meets the space needs of the interior of the rail vehicle, and ensures that the functions of the external equipment are not affected, but also effectively reduces the overall vehicle resistance and achieves energy saving.

[0095] According to the embodiment of the present disclosure, the plurality of skin outer plates are welded on the surface of at least one of the head car, the tail car, and the middle car through a plate beam.

[0096] According to the embodiment of the present disclosure, the skin outer plate with the dimple structure is arranged with a plug-in plate beam structure on the inner side of the skin outer plate when the rail vehicle is installed, and the welding mode is the same as that of other outer plates, for example, double-sided a4 welding angle intermittent fillet welding. The welding mode of the skin outer plate and other outer plates is consistent with the form of the outer plate splicing weld, for example, HV groove welding, and a permanent backing pad is arranged at the back.

[0097] As another aspect of the embodiment of the present disclosure, an experimental method for verifying the drag reduction effect of the skin outer plate is provided, and a wind tunnel and a test model are used for testing.

[0098] According to the embodiment of the present disclosure, the wind tunnel is a pipeline designed according to certain requirements. In this special pipeline, a flow that can be artificially and freely controlled is generated by means of a power device, and various air dynamic tests are carried out according to the principles of relativity and similarity.

[0099] According to the embodiment of the present disclosure, the test model is a scaled-down model of the rail vehicle.

[0100] In an illustrative embodiment, the test model is a 1:8 scaled three-car marshalling model. According to the scaled size of the test train model, the test is carried out in an 8m order low-speed wind tunnel. Table 1 shows the parameters of the first wind tunnel and the second wind tunnel.

[0101] Table 1

[0102]

[0103] In an illustrative embodiment, the first wind tunnel test uses three train model test dedicated scales (six-component box strain scales) to simultaneously measure the aerodynamic force and torque of the model head car, middle car and tail car, and the scales are located in the model cavity. The scales meet the requirements of GJB 2244-1994 “Wind Tunnel Test Strain Scale Specification” and are calibrated before the test. The main performance parameters of the scales are shown in Table 2.

[0104] Table 2

[0105]

[0106] The force test data testing system is a PXI bus testing platform, which has the capabilities of conventional static measurement and dynamic testing, image signal acquisition and processing. The angle control and speed pressure control are respectively realized by corresponding industrial computer systems, and the precision of the speed pressure and attitude angle control systems is ±3‰ and ±0.05° respectively.

[0107] In an illustrative embodiment, the second wind tunnel test uses six-component box strain scales: head car box strain scale, middle car box strain scale and tail car box strain scale. The main parameters of each scale are shown in Table 3. The scales are calibrated by a 500kg self-compensating static calibration table, and the static calibration environment is 23℃ and 20% humidity.

[0108] Table 3

[0109]

[0110] The measurement and control system is a complete distributed measurement and control system formed by connecting field bus control system, VXI bus acquisition system, computer local area network system and other subsystems, which realizes the automatic control and measurement of the wind tunnel test. The wind speed control and angle control are respectively realized by corresponding industrial computer systems, and the precision of the wind speed control and attitude angle control systems is ±0.1m / s and ±0.05° respectively.

[0111] The test is carried out in the corresponding test sections of two 8m×6m wind tunnels. The model angle of attack is kept unchanged at 0°, and the sideslip angle is performed according to the requirements of the test task book. The test uses six-component train force scales to measure aerodynamic forces, i.e. three scales are used to simultaneously measure the forces of the head car, middle car and tail car, and the force scales are located in the cavities of the car models to realize simultaneous and independent force measurement of each car.

[0112] During the test, the vehicle is started at a constant speed, the delay before sampling is 8s, the sampling time is 6s, the sampling frequency of each channel is 100Hz, and the sampling data is averaged.

[0113] Figure 8 An illustrative schematic diagram of a test model car body shaft system according to an embodiment of the present disclosure is shown.

[0114] As Figure 8V represents the running speed of the test model.

[0115] The test coordinate system is defined as the balance axis system, the airflow axis system, and the model body axis system.

[0116] The balance axis system: the origin OT is located at the balance static calibration center, the axis XT is in the length direction of the balance and points to the front end of the balance, the axis YT is perpendicular to the upper surface of the balance and points upward, and the axis Zt is determined according to the right-hand rule.

[0117] The airflow axis system: the origin Oa is located at the center of mass of the head car, the axis Xa is parallel to the airflow direction of the test section and points to the incoming flow direction, the axis Ya is perpendicular to the airflow and points upward, and the axis Za is determined according to the right-hand rule.

[0118] The model body axis system: as shown in Figure 8 The coordinate origin Ot is located in the longitudinal symmetry plane of the vehicle body and is at the same height as the center line of the car height, and the length direction is near the center of gravity. After the balance is installed, the balance static calibration center coincides with the coordinate origin of the body axis system of the corresponding car, the positive direction of the axis Xt is parallel to the longitudinal center line of the vehicle body and points to the front direction (the aerodynamic drag is positive in the negative direction of the X axis), the axis Yt is perpendicular to the bottom surface of the vehicle body and points upward, and the axis Zt is determined according to the right-hand rule. The force data of each car of the test model is given according to the body axis system.

[0119] According to the conventional multi-balance force test data processing program of wind tunnel test, the train aerodynamic force is given according to the body axis system. Combined with the specific process of the test and the details of the test model, the test uses an internal balance, and the external part of the balance support structure is very small, so no support interference correction is performed; the blockage of the train with the roadbed / viaduct model is not greater than 15%, and no blockage correction is performed according to the European train model crosswind test specification EN14067-6; the length of the train whole vehicle model is about 10m, and the horizontal buoyancy correction is performed on each car according to the axial static pressure gradient of the area where each car is located:

[0120] (2);

[0121] wherein, is the drag coefficient, is the initial value of the drag coefficient, is measured before the test starts, and the head car, the middle car, and the tail car areas are -0.0060m-1, -0.0061m-1, and -0.0076m-1, respectively, and L is the length of the model formation.

[0122] The aerodynamic force and moment calculation formulas of each car are as follows:

[0123] (3);

[0124] (4);

[0125] (5);

[0126] (6);

[0127] (7);

[0128] (8);

[0129] wherein, is the initial value of the drag coefficient; is the lift coefficient; is the side force coefficient; is the roll moment coefficient (heeling moment coefficient); is the side slip moment coefficient; is the pitch moment coefficient; is the roll moment (heeling moment); is the side slip moment; is the pitch moment; is the drag; is the lift; is the side force; S is the reference area, the normal projection area of the car body in the non-pantograph state; B is the lateral reference length, the car width; L is the longitudinal reference length, the length of each section of the car body; q is the speed pressure, the value directly read from the wind tunnel power control system.

[0130] The initial value of the drag coefficient, that is, the uncorrected drag coefficient directly calculated by the calculation formula (3), this coefficient is obtained by axial static pressure gradient correction (that is, formula 2) .

[0131] The parameters of the test model are shown in Table 4.

[0132] Table 4

[0133]

[0134] The first model adopts a 1:8 scaled three-car formation model, and the basic size of the train model is shown in Table 4. The pit array is arranged on the top of the head and tail car streamline area.

[0135] Two pit forms are selected for testing, and the pit size of the scaled model is shown in Table 5.

[0136] Table 5

[0137]

[0138] The test model adopts an ABS shell + aluminum alloy framework, the whole vehicle model is installed above the "rail beam + viaduct", the gap between the vehicle bottom and the rail surface is 18.75 mm, and a 30° guide slope is arranged at the front end of the rail.

[0139] The test adopts a steady speed pressure opening vehicle, the speed pressure is 3001 Pa, the hole density is 1.24 kg / m 3 , the dynamic viscosity coefficient is 1.85*10 5 , and the test wind angle β is in the range of -27.5°~25° (interval 2.5°).

[0140] Figure 9 The head car resistance coefficient repeatability test results according to the embodiments of the present disclosure are schematically shown, Figure 10 The middle car car resistance coefficient repeatability test results according to the embodiments of the present disclosure are schematically shown, Figure 11 The tail car car resistance coefficient repeatability test results according to the embodiments of the present disclosure are schematically shown.

[0141] Before the formal data test, three repeatability tests are performed, and the aerodynamic resistance coefficients of the head car, the middle car and the tail car are compared as shown in Figures 9-11 From the curves and data, the aerodynamic force and moment of the head car, the middle car and the tail car are good in repeatability, the rules are reasonable, which shows that the test system is stable and meets the needs of the present test.

[0142] Figure 12 The head car resistance coefficients of different pit schemes according to the embodiments of the present disclosure are schematically shown, Figure 13 The middle car car resistance coefficients of different pit schemes according to the embodiments of the present disclosure are schematically shown, Figure 14 The tail car car resistance coefficients of different pit schemes according to the embodiments of the present disclosure are schematically shown.

[0143] Through test test, the resistance coefficient comparison curve is as shown in Figures 12-14 Under the three-carriage formation, compared with the smooth model (Q0), the tail car resistance of the pit scheme Q1 increases, and the head car resistance and the middle car resistance decrease; the head car resistance, the middle car resistance and the tail car resistance of the pit scheme Q2 all decrease.

[0144] Comparing the resistance coefficients of different pit schemes near 0° side slip, compared with the smooth model Q0, the head car resistance of the pit scheme Q1 decreases by 5.48%, the middle car resistance decreases by 0.64%, the tail car resistance increases by 0.10%, and the whole vehicle resistance decreases by 1.39%; the head car resistance of the pit scheme Q2 decreases by 8.12%, the middle car resistance decreases by 4.67%, the tail car resistance increases by 1.13%, and the whole vehicle resistance decreases by 3.61%. It can be seen that the drag reduction effect under the small pit is better.

[0145] The second model adopts a 1:8 scaled model of three vehicles in a train set. The basic dimensions of the train model are shown in Table 4. Different distribution areas, different sizes, different lateral and longitudinal spacings of hemispherical pits are arranged on the top of the head and tail vehicles of the model to study the influence of the pits on the aerodynamic drag.

[0146] In view of the length of the streamlined head of the train and the curved modeling features, 12 pit combination forms listed in Table 6 are set. In addition, pits are also set in part of the roof area of the train straight section in combination with the existing structure of the test model.

[0147] Table 6 Pit scheme parameters of the second model (unit: mm)

[0148]

[0149] The test model adopts an ABS shell + aluminum alloy framework. In order to realize the separate force measurement of the head vehicle, the middle vehicle and the tail vehicle of the EMU model, a gap (for example, a gap of about 5 mm) is maintained between the windshields of each vehicle section, a circular ring gap (for example, a circular ring gap of about 5 mm) is formed between the outer surface of each leg of the balance support and the vehicle bottom plate, and the bottom of each wheel of the EMU bogie is cut off a circular arc to maintain a gap (for example, a gap of about 5 mm) between the wheel bottom and the track, so that each vehicle compartment becomes an independent force measurement unit.

[0150] This test adopts a steady speed pressure opening vehicle, the speed pressure is 2324 Pa (the wind speed is about 65 m / s), the density in the hole is 1.15 kg / m 3 , the dynamic viscosity coefficient is 1.79 x 10 5 , the maximum test wind speed 65 m / s corresponds to a Reynolds number of about 1.81 x 10 6 , and the side wind angle β is 0°.

[0151] Before the formal data test, 5 repeated tests were carried out, and the repeatability accuracy is shown in Table 7. From the data, when β = 0°, the accuracy of the drag coefficient Cx of the head vehicle, the middle vehicle and the tail vehicle is 0.0006, 0.0007 and 0.0009 respectively; the repeatability accuracy of the lift coefficient Cy is 0.0020, 0.0017 and 0.0030 respectively; the accuracy of Mx is 0.0006, 0.0001 and 0.0002 respectively; the accuracy of My is 0.0068, 0.0030 and 0.0037 respectively; the accuracy of Mz is 0.0004, 0.0002 and 0.0003 respectively, and the repeatability test accuracy of each coefficient meets the test requirements.

[0152] Table 7 Repeatability test accuracy

[0153]

[0154] The effects of the various dimple schemes on the resistance are measured by wind tunnel tests and shown in Table 8.

[0155] Table 8 Resistance coefficients of various dimple schemes of the second model

[0156]

[0157] As shown in Table 8, increasing the coverage of dimples in the streamline region makes the drag reduction effect worse. Arranging dimples in the rear region of the streamline has a better drag reduction effect. The three-vehicle drag reduction is 0.93% when the coverage is 0.3L; the three-vehicle drag increase is 0.73% when the coverage is 0.5L; and the three-vehicle drag increase is 0.91% when the coverage is 0.9L.

[0158] Figure 15 A bar chart showing the effects of dimple radius 0.6-1.0 mm, lateral spacing 6 mm, and longitudinal spacing 18 mm on the drag reduction effect according to an embodiment of the present disclosure is schematically shown; Figure 16 A bar chart showing the effects of dimple radius 1.0-3.0 mm, lateral spacing 10 mm, and longitudinal spacing 30 mm on the drag reduction effect according to an embodiment of the present disclosure is schematically shown; Figure 17 A bar chart showing the effects of dimple radius on the aerodynamic drag according to an embodiment of the present disclosure is schematically shown.

[0159] As shown in Table 8, increasing the coverage of dimples in the streamline region makes the drag reduction effect worse. Arranging dimples in the rear region of the streamline has a better drag reduction effect. The three-vehicle drag reduction is 0.93% when the coverage is 0.3L; the three-vehicle drag increase is 0.73% when the coverage is 0.5L; and the three-vehicle drag increase is 0.91% when the coverage is 0.9L. Figures 15-17 As shown in Table 8, increasing the coverage of dimples in the streamline region makes the drag reduction effect worse. Arranging dimples in the rear region of the streamline has a better drag reduction effect. The three-vehicle drag reduction is 0.93% when the coverage is 0.3L; the three-vehicle drag increase is 0.73% when the coverage is 0.5L; and the three-vehicle drag increase is 0.91% when the coverage is 0.9L.

[0160] Figure 18 A bar chart showing the effects of lateral spacing on the aerodynamic drag according to an embodiment of the present disclosure is schematically shown.

[0161] As shown in Table 8, increasing the coverage of dimples in the streamline region makes the drag reduction effect worse. Arranging dimples in the rear region of the streamline has a better drag reduction effect. The three-vehicle drag reduction is 0.93% when the coverage is 0.3L; the three-vehicle drag increase is 0.73% when the coverage is 0.5L; and the three-vehicle drag increase is 0.91% when the coverage is 0.9L. Figure 18 As shown in Table 8, increasing the coverage of dimples in the streamline region makes the drag reduction effect worse. Arranging dimples in the rear region of the streamline has a better drag reduction effect. The three-vehicle drag reduction is 0.93% when the coverage is 0.3L; the three-vehicle drag increase is 0.73% when the coverage is 0.5L; and the three-vehicle drag increase is 0.91% when the coverage is 0.9L.

[0162] Figure 19A bar chart showing the effect of longitudinal spacing on aerodynamic drag on the drag reduction effect according to an embodiment of the present disclosure is schematically shown.

[0163] As shown in Figure 19 The drag reduction effect becomes better as the longitudinal spacing of the dimples increases from 12 mm to 24 mm. The three-car drag increases by 2.33% when the longitudinal spacing is 12 mm, the three-car drag increases by 0.73% when the longitudinal spacing is 18 mm, and the three-car drag decreases by 5.10% when the longitudinal spacing is 24 mm.

[0164] In addition, the dimples are arranged on the head car, the middle car and the tail car in the straight section, and the aerodynamic drag of the dimples is tested. The dimple arrangement range includes: the head car, the middle car, the tail car, the middle car air conditioner cover plate, and the middle car pantograph cover plate. The dimple radius is 0.6 mm, the dimple depth is 0.6 mm, the transverse spacing is 6 mm, and the longitudinal spacing is 18 mm. The aerodynamic drag test results are shown in Table 9. As shown in Table 9, arranging dimples on the head car, the middle car and the tail car in the straight section can also reduce the aerodynamic drag of the train, and the three-car drag decreases by 2.65%.

[0165] Table 9 Drag coefficient of dimples arranged on the roof of the straight section car

[0166]

[0167] As can be seen from the above, arranging dimples in the streamline region can achieve drag reduction effect, and the drag reduction effect of the head car and the middle car is not significant, and the drag reduction mainly occurs in the tail car. The dimple radius has a significant effect on the aerodynamic drag, and the relationship is not monotonic, and there is a relatively optimal dimple radius. The transverse spacing and the longitudinal spacing also affect the aerodynamic drag, and the relatively dense transverse spacing and the sparse transverse spacing have good drag reduction effect. For each dimple drag reduction scheme in this test, scheme S5 (covering range 0.5 times the top of the streamline head type, dimple radius 1 mm, dimple depth 1 mm, transverse spacing 6 mm, longitudinal spacing 18 mm) is the best, and the drag reduction is 5.81%.

[0168] The above describes embodiments of the present disclosure. However, these embodiments are only for illustrative purposes, and are not intended to limit the scope of the present disclosure. Although each embodiment is described above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A skin panel, characterized in that, A skin panel is installed on at least a portion of a surface of a rail vehicle, the skin panel including a curved body portion shaped to match a contour of the surface of the rail vehicle to adhere to the surface of the rail vehicle, a plurality of pits arranged in an array being formed along an outer surface of the body portion in a direction perpendicular to the outer surface; wherein a lateral spacing between two pits adjacent in a vehicle width direction of the rail vehicle is 2-4 times a maximum dimension of the pit, and a longitudinal spacing between two pits adjacent in a vehicle length direction of the rail vehicle is 8-10 times the maximum dimension, to reduce air resistance of the rail vehicle during travel of the rail vehicle; a plurality of supports each extending from an inner surface of the body portion toward the surface of the rail vehicle to form an accommodation space accommodating the pits in a row or a column between the body portion and the supports; each of the supports including: two mounting portions mounted on the inner surface of the body portion and located on both sides of the pits in the row or the column; and a connecting portion integrally connected between the two mounting portions and curved away from the body portion to form the accommodation space.

2. The skin panel of claim 1, wherein A periphery of the pit is smoothly connected to the body portion by a transition arc to reduce stress between the body portion and each of the pits.

3. The skin panel of claim 1, wherein, A depth of the pit is equal to half of the maximum dimension, and the maximum dimension ranges from 8 to 48 mm.

4. The skin panel according to any one of claims 1-3, characterized in that, The skin panel is arranged on at least one of a streamlined area on a roof of a head car and a tail car and a roof of a middle car of the rail vehicle.

5. The skin panel of claim 4, wherein, The skin panel is arranged on 30-80% of the streamlined area on the roof of the head car and the tail car and on a straight area on the roof of the head car, the tail car, and the middle car.

6. The skin panel of claim 4, wherein, A cross section of the pit in a depth direction is any one of a semicircular shape, a conical shape, and a polygonal shape.

7. A rail vehicle, characterized by The rail vehicle includes: a head car; a tail car; a middle car connected between the head car and the tail car; and a plurality of skin panels as claimed in any one of claims 1-6 installed on a surface of at least one of the head car, the tail car, and the middle car to reduce air resistance of the rail vehicle during travel of the rail vehicle. The plurality of skin panels are welded on the surface of at least one of the head car, the tail car, and the middle car by a plate beam.

8. A rail vehicle according to claim 7, characterised in that ​

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