A drag reduction system for the tail of high-speed EMUs based on the combination of blowing and suction

Abstract

The present invention provides a drag reduction system for the tail of a high-speed EMU based on the combination of blowing and suction, comprising: the tail of the EMU, a suction area, a blowing area and an air flow module. The suction area is arranged at the separation of the boundary layer above the cab windshield at the tail of the EMU; the blowing area is arranged below the cab windshield at the tail of the EMU; the air flow module is arranged inside the tail of the EMU and is connected to the suction area and the blowing area. The present invention mainly controls the external air flow by setting a blowing area and a small area at the tail of the high-speed EMU, so as to control the pressure difference resistance at the tail and enhance the drag reduction effect.

Description

Technical Field

[0001] The present invention relates to the technical field of aerodynamic drag reduction for high - speed multiple units, and more particularly, to a tail drag reduction system for high - speed multiple units based on the combination of blowing and suction. Background Art

[0002] High - speed multiple unit trains have a large length - to - height ratio. During high - speed running close to the ground, a series of aerodynamic problems different from other land vehicles occur, which are closely related to the train speed and operating environment. These aerodynamic problems mainly include: train meeting, cross - wind effect, tunnel effect, aerodynamic noise, aerodynamic drag, and induced wake, etc., which have attracted extensive attention and research from many scholars and engineers. Among them, aerodynamic drag is the most critical influencing factor in train aerodynamics. As the running speed increases, the aerodynamic drag of the train gradually dominates the running resistance. When the train running speed exceeds 400 km / h, the proportion of the train aerodynamic drag in the total resistance also increases significantly to more than 90%, seriously affecting the running economy and environmental protection of the train and restricting the further speed increase of the train. Since the traditional method of optimizing the head geometry to change the corresponding flow field structure by optimizing the streamline - shaped head has reached its limit, the space for optimization has become smaller and smaller.

[0003] Therefore, it is necessary to design a tail drag reduction system for high - speed multiple units based on the combination of blowing and suction. Summary of the Invention

[0004] In view of the above - mentioned technical problem that the optimization space of the existing drag - reduction method by optimizing the shape is getting smaller and smaller, a tail drag reduction system for high - speed multiple units based on the combination of blowing and suction is provided. The present invention mainly controls the external airflow by setting a blowing area and a small - area at the rear of the high - speed multiple unit, so as to control the pressure - drag at the rear of the vehicle and enhance the drag - reduction effect.

[0005] The technical means adopted by the present invention are as follows:

[0006] A tail drag reduction system for high - speed multiple units based on the combination of blowing and suction, characterized by comprising: the rear of the multiple unit, a suction area, a blowing area, and an airflow module. The suction area is arranged at the separation of the boundary layer above the driver's windshield at the rear of the multiple unit; the blowing area is arranged below the driver's windshield at the rear of the multiple unit; the airflow module is arranged inside the rear of the multiple unit and is connected to the suction area and the blowing area.

[0007] Further, the airflow module includes a suction pipeline, a turbine compressor, a gas storage tank, and a blowing pipeline. The suction pipeline, the turbine compressor, the gas storage tank, and the blowing pipeline are connected in sequence. The suction pipeline is connected to the suction area, and the blowing pipeline is connected to the blowing area.

[0008] Furthermore, there are five rows of 16 suction holes in the suction area, and the diameters and center distances of individual suction holes are kept consistent.

[0009] Furthermore, there are five rows of 16 blowing holes in the blowing area, and the diameters and center distances of individual blowing holes are kept consistent.

[0010] Furthermore, when the total mass flow rate of blowing and suction in the suction area and the blowing area is 4.615 kg / s, the range of the differential pressure drag reduction rate of the trailing car is 7.5% - 9.5%.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] 1. A high-speed EMU tail drag reduction system based on the combination of blowing and suction provided by the present invention sets blowing and suction holes at the tail of the EMU. Through the combined method of blowing and suction, the air in the low negative pressure area above the rear windshield of the car body is transferred to the positive pressure area below the windshield through the internal flow channel of the car. The air is transferred through the air compressor in the flow channel. Through simulation calculation, it is found that this setting only has a drag reduction effect on the differential pressure drag of the trailing car and will not affect the drag of other carriages. And within a certain range of the blowing and suction mass flow rate, the differential pressure drag reduction rate is positively correlated with the increase of the mass flow rate and the number of rows of blowing and suction ports.

[0013] For the above reasons, the present invention can be widely promoted in the fields such as the pneumatic drag reduction technology of high-speed EMUs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0015] Figure 1 It is a schematic structural diagram of a high-speed EMU tail drag reduction system based on the combination of blowing and suction of the present invention.

[0016] Figure 2 It is a right view of a high-speed EMU tail drag reduction system based on the combination of blowing and suction of the present invention.

[0017] Figure 3 It is a top view of a high-speed EMU tail drag reduction system based on the combination of blowing and suction of the present invention.

[0018] Figure 4 It is a pressure coefficient contour map of a high-speed EMU tail drag reduction system based on the combination of blowing and suction of the present invention.

[0019] Figure 5 This is the boundary layer cloud map of the tail of an existing EMU train at a speed of 400 km / h for a tail drag reduction system of a high-speed EMU based on the combination of blowing and suction in the present invention.

[0020] Figure 6 This is the pressure coefficient cloud map of the tail of an existing EMU train at a speed of 400 km / h for a tail drag reduction system of a high-speed EMU based on the combination of blowing and suction in the present invention.

[0021] In the figure: 1. Suction pipeline; 2. Turbine compressor; 3. Gas storage tank; 4. Suction pipeline. Detailed implementation manners

[0022] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0023] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The description of at least one exemplary embodiment below is actually only illustrative and in no way restricts the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] It should be noted that the terms used here are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used here, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations.

[0025] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0026] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom", etc., are usually based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description. Without contrary description, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of the present invention: the orientation words "inner, outer" refer to the inside and outside relative to the contour of each component itself.

[0027] For ease of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "above", etc. may be used here to describe the spatial positional relationships of one device or feature with respect to other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the drawings. For example, if the device in the drawing is inverted, a device described as "above other devices or structures" or "over other devices or structures" will then be positioned "below other devices or structures" or "under other devices or structures". Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations should be made for the spatial relative descriptions used here.

[0028] In addition, it should be noted that the use of words such as "first", "second", etc. to limit components is only for the convenience of differentiating the corresponding components. Without otherwise stating, the above words have no special meaning, and thus should not be construed as limiting the protection scope of the present invention.

[0029] As Figure 1-6As shown in the figure, the present invention provides a drag reduction system for the rear of a high-speed EMU based on the combination of blowing and suction, which is characterized in that it includes: the rear of the EMU, the suction area, the blowing area and the air flow module. The suction area is arranged at the separation of the boundary layer above the windshield of the driver's cab at the rear of the EMU; the blowing area is arranged below the windshield of the driver's cab at the rear of the EMU; the air flow module is arranged inside the rear of the EMU and is connected to the suction area and the blowing area; the air flow module includes an air suction pipeline 41, a turbo compressor 2, a gas storage tank 3 and a blowing pipeline. The air suction pipeline 41, the turbo compressor 2, the gas storage tank 3 and the blowing pipeline are connected in sequence. The air suction pipeline 41 is connected to the suction area, and the blowing pipeline is connected to the blowing area; the suction area is provided with five rows of 16 suction holes each, and the diameter and center distance of each single suction hole are kept consistent; the blowing area is provided with five rows of 16 blowing holes each, and the diameter and center distance of each single blowing hole are kept consistent; when the total mass flow rate of blowing and suction in the suction area and the blowing area is 4.615 kg / s, the range value of the differential pressure drag reduction rate of the tail car is 7.5% - 9.5%.

[0030] Embodiment 1

[0031] As Figure 1-6 shown in the figure, the present invention provides a drag reduction system for the rear of a high-speed EMU based on the combination of blowing and suction. First, through grid division, and using the numerical calculation method based on realizable k-ε to explore the aerodynamic drag characteristics of a three-car formation train, the boundary layer cloud map and pressure coefficient cloud map of the original car's rear are obtained, as shown in Figure 5 and Figure 6 . It is found that within the area where the air flow passes through the sudden change of the rear cross-section, the boundary layer gradually separates and thickens, and the boundary layer gradually stratifies according to the velocity level. Due to the local vacuum above the streamlined rear, the air flow accelerates and forms a negative pressure area; after the air flow passes through the sudden change of the rear cross-section, the velocity becomes smaller and the pressure returns to normal. Due to the change of the rear curved surface, the boundary layer detaches from the train surface and forms a positive pressure near the nose of the rear.

[0032] According to the distribution of the boundary layer and pressure during the steady operation of the high-speed train, blowing and suction holes are set in two areas of the tail car to reduce the aerodynamic drag of the tail car. An air suction area is set in the boundary layer separation area of the tail car to remove the low-momentum fluid and suppress the flow separation; a blowing area is set in the nose area of the tail car to control the wake flow and improve the rear air flow structure. See Figure 1 , in which the internal structure includes an air suction pipeline 1, a turbo compressor 2, a gas storage tank 3, and a blowing pipeline 4.

[0033] The blowing and suction ports at the rear of the train are respectively set to 5 rows, and the interference effect between the blowing holes and the coupler fairing is not considered for the time being. The appearance of the rear of the EMU is as shown in Figure 2 and3 As shown, the structure of the train bogie is omitted in this appearance, and only the air vent distribution along the upper and lower edges of the windshield is highlighted. Each row of air vents contains 16 air holes, and the diameter and center distance of each single air hole are kept consistent. The number of air holes in the air suction area and the air blowing area is the same and has an impact. The main factors affecting the drag reduction effect at the train tail are related to the actual number of air blowing and suction of the air vents, the mass flow rate of the blown and sucked air, the mass flow velocity, and so on.

[0034] From Figure 4 Judging from the pressure coefficient contour map of the EMU tail, the negative pressure area on the surface of the windshield blowing and suction area of the EMU tail of the present invention is approximately equal to that of the existing EMU tail, but the difference in the pressure difference amplitude between the two is relatively large. The EMU tail of the present invention has a better drag reduction effect after the blowing and suction action. The nose tip of the tail shows a greater positive pressure amplitude compared to the existing EMU tail, making the pressure difference amplitude of the tail smaller, thereby reducing the pressure difference drag of the last car of the EMU. In this calculation example, when the total mass flow rate of the blowing and suction is 4.615 kg / s, the pressure difference drag reduction rate of the last car reaches 7.97%.

[0035] The present invention sets blowing and suction holes at the tail of the EMU. Through the combined method of blowing and suction, the air in the low negative pressure area above the windshield of the car tail is transferred to the positive pressure area below the windshield through the internal flow channel of the car. The air is transferred through the air compressor in the flow channel. It is found through simulation calculation that this setting only has a drag reduction effect on the pressure difference drag of the last car and will not affect the drag of other carriages. And when the mass flow velocity of the blowing and suction is within a certain range, the pressure difference drag reduction rate is positively correlated with the increase of the mass flow velocity and the number of rows of the blowing and suction ports.

[0036] In the long run, since the limitations of traditional drag reduction methods are gradually emerging, if the flow control drag reduction technology combining blowing and suction is applied to high-speed EMUs, it will be able to overcome the bottleneck of speed increase brought about by the aerodynamic effect of EMUs and respond to the national design goals of higher speed, more comfort, and more economical and environmental protection for the next generation of high-speed trains. At present, the preliminary tests of the CR450 EMU developed by CRRC have been successfully carried out in April this year, and the prototype of the high-speed maglev train with a speed of 600 km / h has also appeared in the public eye. This shows that whether it is the research and development of faster wheel-rail trains or high-speed maglev trains, improving the running speed of trains is the symbol and the goal pursued by the development of railway science and technology, and train aerodynamics has always been the object of much attention. Therefore, the drag reduction combining blowing and suction can be applied to higher-speed EMUs to reduce the energy consumption caused by aerodynamic drag.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A drag reduction system for the tail of a high-speed EMU based on the combination of blowing and suction, characterized in that, Including: The rear of the multiple unit train, the air suction area, the air blowing area and the air flow module. The air suction area is arranged at the separation of the boundary layer above the driver's windshield at the rear of the multiple unit train; the air blowing area is arranged below the driver's windshield at the rear of the multiple unit train; the air flow module is arranged inside the rear of the multiple unit train and is connected to the air suction area and the air blowing area. The air suction area is provided with five rows of 16 suction holes each, and the diameter and center distance of each single suction hole are kept consistent; the air blowing area is provided with five rows of 16 blowing holes each, and the diameter and center distance of each single blowing hole are kept consistent; when the total mass flow rate of air suction and blowing in the air suction area and the air blowing area is 4.615 kg / s, the range of the pressure difference drag reduction rate of the tail car is 7.5% - 9.5%.

2. The high-speed EMU tail drag reduction system based on the combination of blowing and suction according to claim 1, characterized in that The air flow module includes an air suction pipeline, a turbine compressor, a gas storage tank and an air blowing pipeline. The air suction pipeline, the turbine compressor, the gas storage tank and the air blowing pipeline are connected in sequence. The air suction pipeline is connected to the air suction area, and the air blowing pipeline is connected to the air blowing area.

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