Low-vacuum pipeline train incoming flow direct connection type test bench

Abstract

The invention relates to the technical field of aerodynamic tests of trains in pipe tunnels, and discloses a low-vacuum pipeline train incoming flow direct connection type test bed which comprises a shock tube driving section, a gas compressor, a diaphragm, a metal piece, a charging and discharging box, a shock tube driven section, a vacuum pump, a test section, an aircraft scaling model and a pressure relief section. The front end of the driven section of the shock tube is connected with the rear end of the driving section of the shock tube, the rear end of the driven section of the shock tube is connected with the front end of the test section, the side wall of the driven section of the shock tube is connected with the vacuum pump, the diaphragm is arranged at the joint of the driven section of the shock tube and the driving section of the shock tube, and the metal piece is connected with the diaphragm and the charge-discharge box. The aircraft scaling model is arranged in the test section through the supporting pieces on the two sides, high-pressure air is inflated into the shock tube driving section in advance through the air compressor, and low-pressure air is preset in the driven section, the test section and the pressure relief section of the shock tube through suction of the vacuum pump.

Description

Technical Field

[0001] The present invention relates to the technical field of aerodynamic testing technology for trains in pipelines, and particularly relates to a direct-connected test bench for the oncoming flow of a low-vacuum pipeline train. Background Art

[0002] Ultra-high-speed low-vacuum pipeline trains are one of the important development directions for future ground high-speed transportation. By means of covering maglev trains with low-vacuum pipelines, the aerodynamic drag can be significantly reduced, making it possible for high-subsonic and even supersonic ground transportation. Different from running on open lines, ultra-high-speed trains making long-distance round trips are confined to an extremely narrow pipeline space. When the train speed is at medium and low speeds (such as 400 km / h corresponding to Ma 0.325), the pipeline is in a flow-through state, and the flow is mainly characterized by local flow separation and vortex structures of the train, which affect the stable operation of the train; when running at high speeds (such as 600 km / h corresponding to Ma 0.49, 1000 km / h corresponding to Ma 0.815), large-scale transonic flows dominated by choked shock waves in the pipeline are usually induced, resulting in a sharp increase in the train resistance and deterioration of the aerodynamic heat and acoustic environment of the pipeline.

[0003] The flow of pipeline trains has complex characteristics of large scale, multi-dimension, and wide speed range. Existing research still has the cognitive limit of "simulation discovery to experimental verification", and targeted experimental methods are a recognized difficult problem. Wind tunnel equipment is considered to be one of the most commonly used and effective tools for aerodynamic testing, generally applied in transient internal and external flow environments in open / semi-open spaces, but it is difficult to reproduce the aerodynamic environment in the pipeline space. Especially when a vehicle runs at high speed and causes choking, it will generate upstream and downstream shock waves that cause significant interference to the test pipeline.

[0004] Currently, there is no targeted experimental technology for the aerodynamic environment in the pipeline space at home and abroad. Summary of the Invention

[0005] The present invention provides a direct-connected test bench for the oncoming flow of a low-vacuum pipeline train, which can solve the technical problems in the prior art.

[0006] The present invention provides a direct-connection test bench for the oncoming flow of a low-vacuum pipeline train. The test bench includes a shock tube driving section, a compressor, a diaphragm, a metal part, a charge and discharge box, a shock tube driven section, a vacuum pump, a test section, a scaled-down model of a vehicle, and a pressure relief section. The side wall of the shock tube driving section is connected to the compressor. The front end of the shock tube driven section is connected to the rear end of the shock tube driving section. The rear end of the shock tube driven section is connected to the front end of the test section. The side wall of the shock tube driven section is connected to the vacuum pump. The diaphragm is arranged at the connection between the shock tube driven section and the shock tube driving section. The metal part is connected to the diaphragm and the charge and discharge box. The rear end of the test section is connected to the pressure relief section. The scaled-down model of the vehicle is arranged in the test section through supporting parts on both sides. High-pressure air is pre-filled into the shock tube driving section by the compressor. After charging, the charge and discharge box instantaneously discharges high voltage to heat the metal part. The shock tube driven section, the test section, and the pressure relief section are preset with low-pressure gas by suction of the vacuum pump.

[0007] Preferably, the shock tube driving section is a straight cylindrical structure with a constant circular inner cross-section, and the front end of the shock tube driving section is closed.

[0008] Preferably, the shock tube driven section is a straight cylindrical structure with a constant circular inner cross-section, and both ends of the shock tube driven section are open.

[0009] Preferably, the test section is a through-type structure with a special-shaped pipe cross-section.

[0010] Preferably, the test section is an arched cross-section pipe or a combined pipe of an arch and a channel.

[0011] Preferably, the cross-sectional area of the special-shaped pipe cross-section of the test section is the same as the cross-sectional area of the circular inner cross-section of the shock tube driven section.

[0012] Preferably, the pressure relief section is a through-type structure with a special-shaped pipe cross-section, and the rear end of the pressure relief section is closed.

[0013] Preferably, the cross-sectional configuration of the pressure relief section is the same as the cross-sectional configuration of the test section.

[0014] Preferably, the diaphragm is a polyester diaphragm.

[0015] Preferably, the metal part is a metal wire.

[0016] Through the above technical solutions, a shock tube can be used to design the oncoming flow in front of a pipeline train under wide speed ranges and extensive low-vacuum conditions, and the designed oncoming flow can be directly led to the test area, eliminating the influence of the interference at the front and rear ends of the pipeline on the test area to be tested in traditional wind tunnel tests, accurately establishing a through-flow / choked flow field in the pipe tunnel space. The system is simple and easy to implement and has a low cost, can provide a general and efficient test platform for the air dynamics problems of trains in similar pipe tunnel spaces, and can be used as a basic research and development platform for key aerodynamic technologies in the engineering development stage of this field. Description of the Drawings

[0017] The accompanying drawings included are used to provide a further understanding of the embodiments of the present invention, which form a part of the specification, illustrate the embodiments of the present invention, and together with the written description explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 Shows a schematic diagram of a direct connection test bench for the oncoming flow of a low-vacuum pipeline train according to an embodiment of the present invention;

[0019] Figure 2 Shows the Mach number contour map according to an embodiment of the present invention;

[0020] Figure 3 Shows a schematic diagram of the schlieren of the test flow field according to an embodiment of the present invention. Detailed implementation manners

[0021] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. The following description of at least one exemplary embodiment 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 belong to the scope of protection of the present invention.

[0022] It should be noted that the terms used herein are only for describing the specific implementation manners and are not intended to limit the exemplary embodiments according to the present application. As used herein, 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 combinations thereof.

[0023] Unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that for the sake of convenience in 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, the said 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 does not need to be further discussed in subsequent drawings.

[0024] Figure 1 A schematic diagram of a direct-connected test bench for the oncoming flow of a low-vacuum pipeline train according to an embodiment of the present invention is shown.

[0025] As Figure 1 shown, an embodiment of the present invention provides a direct-connected test bench for the oncoming flow of a low-vacuum pipeline train. Among them, the test bench includes a shock tube driving section 1, a compressor 2, a diaphragm 3, a metal part 4, a charge and discharge box (high-voltage charge and discharge box) 5, a shock tube driven section 6, a vacuum pump 7, a test section 8, a scaled-down model of an aircraft 9, and a pressure relief section 10. The side wall of the shock tube driving section 1 is connected to the compressor 2. The front end of the shock tube driven section 6 is connected to the rear end of the shock tube driving section 1. The rear end of the shock tube driven section 6 is connected to the front end of the test section 8. The side wall of the shock tube driven section 6 is connected to the vacuum pump 7. The diaphragm 3 is arranged at the connection between the shock tube driven section 6 and the shock tube driving section 1. The metal part 4 is adhesively bonded to the surface of the diaphragm 3 and connected to the discharge electrode of the charge and discharge box 5. The rear end of the test section 8 is connected to the pressure relief section 10. The scaled-down model of the aircraft 9 is arranged in the test section 8 through support members on both sides (to approximately present a suspended state). High-pressure air is pre-filled into the shock tube driving section 1 by the compressor 2. After charging, the charge and discharge box 5 instantaneously discharges high voltage to heat the metal part 4. By sucking through the vacuum pump 7, the shock tube driven section 6, the test section 8, and the pressure relief section 10 are preset with low-pressure gas.

[0026] Through the above technical solution, it is possible to use a shock tube to design the oncoming flow in front of a pipeline train under wide speed ranges and extensive low-vacuum conditions, and directly conduct the designed oncoming flow to the test area, eliminating the influence of the interference of the front and rear ends of the pipeline on the test area to be tested in traditional wind tunnel tests, accurately establishing a through-flow / choked flow field in the pipe tunnel space. This system is simple and easy to implement and has a low cost, can provide a general and efficient test platform for the aerodynamic problems of trains in similar pipe tunnel spaces, and can be used as a basic research and development platform for key aerodynamic technologies in the engineering development stage of this field.

[0027] According to an embodiment of the present invention, the driver section 1 of the shock tube is a straight cylindrical structure with a constant circular inner cross-section, and the front end of the driver section 1 of the shock tube is closed.

[0028] According to an embodiment of the present invention, the driven section 6 of the shock tube is a straight cylindrical structure with a constant circular inner cross-section, and both ends of the driven section 6 of the shock tube are open.

[0029] According to an embodiment of the present invention, the test section 8 is a full-length structure with a special-shaped pipe cross-section.

[0030] According to an embodiment of the present invention, the test section 8 is a pipe with an arched cross-section or a pipe combining an arch and a channel.

[0031] According to an embodiment of the present invention, the cross-sectional area of the special-shaped pipe cross-section of the test section 8 is the same as the cross-sectional area of the circular inner cross-section of the driven section 6 of the shock tube.

[0032] Thus, the disturbance caused by the variable cross-section configuration can be minimized.

[0033] According to an embodiment of the present invention, the pressure relief section 10 is a full-length structure with a special-shaped pipe cross-section, and the rear end of the pressure relief section 10 is closed.

[0034] According to an embodiment of the present invention, the cross-sectional configuration of the pressure relief section 10 is the same as the cross-sectional configuration of the test section 8.

[0035] According to an embodiment of the present invention, the diaphragm 3 is a polyester diaphragm.

[0036] According to an embodiment of the present invention, the metal part 4 is a metal wire.

[0037] The following describes a direct-connected test bench for the oncoming flow of a low-vacuum pipeline train according to the present invention with reference to examples.

[0038] Specifically, a direct-connected test bench for the oncoming flow of a low-vacuum pipeline train includes: a driver section 1 of the shock tube, a compressor 2, a polyester diaphragm, a metal wire, a high-voltage charging and discharging box 5, a driven section 6 of the shock tube, a vacuum pump 7, a test section 8, a scaled-down model 9 of an aircraft, and a pressure relief section 10.

[0039] The driver section 1 of the shock tube is a straight cylindrical structure with a constant circular inner cross-section, its front end is closed, and its side wall is connected to the compressor 2; a polyester diaphragm is clamped at the connection between it and the driven section 6 of the shock tube; high-pressure air can be pre-filled into the driver section 1 of the shock tube through the compressor 2.

[0040] The driven section 6 of the shock tube is a straight cylindrical structure with a constant circular inner cross-section, both of its ends are open, its front end is connected to the driver section 1 of the shock tube, its rear end is connected to the test section 8, and its side wall is connected to the vacuum pump 7.

[0041] The polyester film is clamped between the driving section 1 and the driven section 6 of the shock tube. Its surface is adhered to the metal wire, and the metal wire is connected to the high-voltage charge and discharge box 5. After the high-voltage charge and discharge box 5 is charged, instantaneous high-voltage discharge heating of the metal wire can be achieved.

[0042] The test section 8 is a full-length structure with a special-shaped pipe cross-section, such as an arched cross-section pipe or a pipe combined with an arched and grooved channel. Its front end is connected to the driven section 6 of the shock tube, and the rear end is connected to the pressure relief section 10; the cross-sectional area of the special-shaped pipe in the test section 8 is kept consistent with the circular cross-sectional area of the driven section 6 of the shock tube to minimize the disturbance caused by the variable cross-section configuration; a scaled-down model 9 of the vehicle to be tested is placed inside the test section 8 and fixed by two side support rods to approximately present a suspended state.

[0043] The pressure relief section 10 is a full-length structure with a special-shaped pipe cross-section, which is consistent with the cross-section configuration of the test section 8, and its rear end is closed.

[0044] By pumping with the vacuum pump 7, the driven section 6 of the shock tube, the test section 8 and the pressure relief section 10 can be preset with low-pressure gas.

[0045] The operating principle of the low-vacuum pipe train incoming flow direct connection test bench of the present invention is as follows:

[0046] First, the Mach number and pressure of the incoming flow in front of the vehicle in the pipe can be calculated in advance through similarity theory to obtain the preset air pressure values of the driving section and the driven section of the shock tube. Then, gas is filled into the driving section of the shock tube by the compressor to the high-pressure design value, and the driven section, the test section and the pressure relief section of the shock tube are pumped to the low-pressure design value by the vacuum pump. The metal wire is heated by discharging electricity from the high-voltage charge and discharge box, and the polyester film closely adhered to the metal wire is instantly melted and broken. The high-pressure gas in the driving section of the shock tube rushes into the low-pressure gas in the driven section of the shock tube, generating a right-traveling shock wave and a left-traveling rarefaction wave. Under the action of the right-traveling shock wave, the low-pressure gas is pressurized and accelerated to form the test air flow required by the scaled-down model of the vehicle. The test air flow continuously flows through the test section and the pressure relief section, and a pipe space through-flow / choked flow is quickly established in the vicinity of the vehicle, thereby enabling relevant mechanical tests such as flow field observation, force measurement, pressure measurement, and sound measurement.

[0047] Next, one embodiment of the present invention will be further described in detail.

[0048] In this example, the actual problem under investigation is that the hypersonic vehicle runs in the pipe at 1000 km / h, corresponding to Ma0.815, the equivalent cross-section of the pipe is 50 m 2 , and the pipe is in a low-vacuum environment of 1 kPa; the hypersonic vehicle has a single-section bullet-shaped appearance with a length of 30 m, and the maximum cross-section in the middle of the train is 12.5 m 2, the pipeline blockage ratio is about 0.25. Considering that the scale ratio of the vehicle is 120 times, the length of the scaled vehicle is 0.25 m. According to the similarity criterion, the required oncoming flow Mach number of the vehicle is calculated to be Ma = 0.815, and the pressure is 120 kPa. The driving section pressure of the shock tube can be further inversely designed to be 600 kPa for the high pressure and 35 kPa for the driven section of the shock tube for the low pressure.

[0049] For the oncoming flow direct connection test of the above hypersonic vehicle running at 1000 km / h, the total length of the designed direct connection test bench is 12 m. Among them, the length of the driving section 1 of the shock tube is 3 m, the length of the driven section 6 of the shock tube is 6 m, the length of the test section 8 is 0.5 m, the length of the pressure relief section 10 is 2.5 m, and the length of the scaled model 9 of the vehicle is 0.25 m.

[0050] Before the test, a quasi-one-dimensional numerical simulation was used to quickly evaluate the operating state of the direct connection bench. The Mach number contour map is as Figure 2 shown. Consistent with the theoretical design, when the polyester diaphragm 3 ruptures, a right-traveling shock wave is generated, and the pre-set low-pressure gas in the driven section 6 of the shock tube is pressurized and accelerated to 120 kPa and Ma 0.815. The test oncoming flow flows through the test section 8, and a choked flow is established in the gap between the scaled model 9 of the vehicle and the pipeline. The test time is about 8 ms.

[0051] The above oncoming flow direct connection test bench of the present invention was used for the test. The schlieren of the test flow field is as Figure 3 shown, and the numerical simulation results are also given for comparison. The results show that the oncoming flow direct connection test can reproduce the flow field structure of the high-speed operation of the pipeline vehicle to a high degree, effectively solve the problem of reproducing the aerodynamic environment in the pipeline space, has a high reproduction degree, is simple and easy to operate, and has a low test cost.

[0052] It can be seen from the above embodiments that by constructing a direct connection test bench through the shock tube directly connecting to the pipeline train test area, compared with the prior art, it has at least the following advantages:

[0053] 1. The driving principle of the shock tube has an exact theoretical solution, which can accurately manufacture and control the oncoming flow in front of the vehicle and strictly meet the similarity criteria of Mach number and flow Reynolds number.

[0054] 2. The shock tube is directly connected to the test section of the pipeline vehicle, and it is ensured that their cross-sectional areas are the same, which can eliminate the influence of significant interference caused by the front and rear ends of the limited pipeline test section in the wind tunnel test, and accurately establish a through-flow / choked flow in the vehicle test area, effectively solving the problem of reproducing the aerodynamic environment of the pipeline vehicle in the pipeline space.

[0055] 3. Compared with wind tunnel equipment, the direct connection test bench has the characteristics of small and precise, simple and easy to operate, low construction cost and low operation cost.

[0056] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom", etc. is usually based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description. Without contrary explanation, 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. Therefore, it should not be construed as a limitation on the protection scope of the present invention; the orientation words "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0057] For the convenience of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "above" etc. can be used here to describe the spatial positional relationship between a device or feature shown in the drawings and other devices or features. It should be understood that the spatial relative terms are intended to cover different orientations in use or operation in addition to the orientation described in the drawings for the device. For example, if the device in the drawing is inverted, the device described as "above other devices or structures" or "over other devices or structures" will then be positioned as "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 can 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.

[0058] 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. Therefore, it should not be construed as a limitation on the protection scope of the present invention.

[0059] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A direct-connected test bench for the oncoming flow of a low-vacuum pipeline train, characterized in that, The test bench includes a shock tube driver section (1), a compressor (2), a diaphragm (3), a metal part (4), a charge and discharge box (5), a shock tube driven section (6), a vacuum pump (7), a test section (8), a scaled-down model of the vehicle (9), and a pressure relief section (10). The side wall of the shock tube driver section (1) is connected to the compressor (2). The front end of the shock tube driven section (6) is connected to the rear end of the shock tube driver section (1). The rear end of the shock tube driven section (6) is connected to the front end of the test section (8). The side wall of the shock tube driven section (6) is connected to the vacuum pump (7). The diaphragm (3) is arranged at the connection between the shock tube driven section (6) and the shock tube driver section (1). The metal part (4) is connected to the diaphragm (3) and the charge and discharge box (5). The rear end of the test section (8) is connected to the pressure relief section (10). The scaled-down model of the vehicle (9) is arranged in the test section (8) through support members on both sides. High-pressure air is pre-filled into the shock tube driver section (1) by the compressor (2). After charging, the charge and discharge box (5) instantaneously discharges high voltage to heat the metal part (4). The shock tube driven section (6), the test section (8), and the pressure relief section (10) are pre-set with low-pressure gas by suction of the vacuum pump (7).

2. The test bench according to claim 1, characterized in that, The shock tube driver section (1) is a straight cylindrical structure with a constant circular inner cross-section, and the front end of the shock tube driver section (1) is closed.

3. The test bench according to claim 2, characterized in that, The shock tube driven section (6) is a straight cylindrical structure with a constant circular inner cross-section, and both ends of the shock tube driven section (6) are open.

4. The test bench according to claim 3, characterized in that, The test section (8) is a full-length structure with a special-shaped pipe cross-section.

5. The test bench according to claim 4, characterized in that, The test section (8) is a pipe with an arched cross-section or a pipe combining an arch and a channel.

6. The test bench according to claim 5, characterized in that, The cross-sectional area of the special-shaped pipe cross-section of the test section (8) is the same as the cross-sectional area of the circular inner cross-section of the shock tube driven section (6).

7. The test bench according to claim 6, characterized in that, The pressure relief section (10) is a full-length structure with a special-shaped pipe cross-section, and the rear end of the pressure relief section (10) is closed.

8. The test bench according to claim 7, characterized in that, The cross-sectional configuration of the pressure relief section (10) is the same as the cross-sectional configuration of the test section (8).

9. The test bench according to any one of claims 1-8, characterized in that, The diaphragm (3) is a polyester diaphragm.

10. The test bench according to any one of claims 1-8, characterized in that, The metal part (4) is a metal wire.

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