Aerodynamic acoustic scale model of high-speed rail tunnel based on whole vehicle environment wind tunnel

Abstract

The invention relates to a high-speed rail tunnel aerodynamic acoustic scale model based on a whole vehicle environment wind tunnel. The model comprises a fan, a first contraction section, a straight section, a second contraction section, a low-speed nozzle, a test bed, a collector, a flow channel, a high-speed nozzle, a tunnel section and a diffusion diffuser. One end of the high-speed nozzle is connected with the low-speed nozzle; one end of the diffusion diffuser is connected with the collector and the other end of the tunnel section; the high-speed rail model is mounted in the tunnel section; baffles are arranged in the diffusion diffuser and divide the diffusion diffuser into a plurality of sub-diffusion diffusers. Compared with the prior art, the device is provided with a wind tunnel based on the whole vehicle environment, the airflow velocity is increased through the high-speed nozzles, and various complex working conditions such as meeting and parallelization of high-speed trains in a tunnel can be simulated; and dynamic pressure of airflow flowing at a high speed is converted into static pressure through the diffusion diffuser, so that the impact of the airflow on the flow guide plate is relieved, and meanwhile, a certain degree of energy recovery of the whole vehicle environment wind tunnel is achieved.

Description

Technical Field

[0001] The present invention relates to the wind tunnel technology of ground vehicles, and particularly to a high-speed rail tunnel aerodynamic acoustic scale model based on a full-vehicle environment wind tunnel. Background Art

[0002] Rail transit has become the main mode of long-distance travel for residents. The aerodynamic and aerodynamic noise performance of high-speed trains is a key R & D technology in rail transit. Especially the aerodynamic acoustic problems of high-speed vehicles passing through tunnels have become a hot topic in current research due to their complexity and challenges. At present, the research on the aerodynamics and wind noise of high-speed train tunnels at home and abroad basically stays at the level of full-scale vehicle experiments and numerical simulation. To ensure the accuracy and precision of numerical simulation, high-density grids and high-quality models are required, which usually consume a large amount of computing resources. Especially for the research on long tunnels and transient effects (such as pressure waves, micro-pressure waves, wind noise), it takes a long time and costs a lot.

[0003] However, the full-scale vehicle experiment on site is costly, requiring the scheduling of train lines, the installation of a large number of sensors and a large amount of human resources; affected by the weather, uncontrollable factors such as external wind speed and humidity will make the experimental results uncontrollable or even unable to continue; there are also certain blind spots in the measurement of aerodynamic characteristics, such as the flow field distribution at the tunnel entrance is difficult to measure.

[0004] The wind tunnel of ground vehicles is a commonly used large test facility for studying vehicle aerodynamic characteristics, with advantages such as precise parameter adjustment, the ability to simulate extreme conditions, high-precision measurement, and repeatable testing. By similarity criteria (such as Reynolds number, Mach number), a scale model can be designed for low-cost testing. In recent years, rich results have been achieved in the high-speed rail aerodynamic and acoustic test research mainly based on the aerodynamic acoustic full-vehicle wind tunnel. For example: The wind tunnel test research on pre-branched cables in high-speed railway tunnels by the China Architecture Design and Research Group measured the aerodynamic forces on the cables when the train passed through the tunnel at a speed of 36 - 180 Km / h. The research progress of train aerodynamics in Central South University, the research on train aerodynamic performance, and the shape and structure design method are based on the largest aerospace low-speed wind tunnel in Asia. An active floor facility was designed to eliminate the influence of the floor boundary layer. On this basis, three large-scale wind tunnel experiments were completed, including the train head shape test, the component combination optimization test, the complex formation train and the tail flow field test. However, at present, the maximum wind speed of most full-vehicle environment wind tunnels is between 220 K / h - 250 Km / h, which cannot reach the high-speed rail operation speed. The wind tunnel test for the tunnel environment is basically blank, and technical problems such as small tunnel aspect ratio, distorted inlet wind speed, and insufficient wind speed still exist.

[0005] After retrieval, the application publication number CN112834160A discloses a train whole - vehicle environmental wind tunnel test section, specifically disclosing: The test section includes a test section main body and a plenum - like structure. Among them, the test section main body is used to provide a test site for the train whole - vehicle environmental simulation test; the plenum - like structure is a cavity structure with a hollow interior, one end is connected to the wind tunnel contraction section and the nozzle section, and the other end is connected to the test section main body, and the cross - sectional area of the connection with the test section main body is the same, and this cross - sectional area is larger than the cross - sectional area of the nozzle section, and is used to expand the nozzle section to the test section main body. However, the wind speed of this existing technology is not sufficient to meet the requirements of train operation, and there is a serious problem of jet effect after the tunnel exit.

[0006] In summary, how to design a tunnel model that can increase the wind speed and improve the jet effect at the tunnel exit is a technical problem to be solved. Summary of the Invention

[0007] The purpose of the present invention is to provide a high - speed rail tunnel aerodynamic acoustic scale model based on the whole - vehicle environmental wind tunnel to overcome the defects of insufficient wind speed and serious jet effect after the tunnel exit in the above - mentioned existing technology.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] According to one aspect of the present invention, a high - speed rail tunnel aerodynamic acoustic scale model based on the whole - vehicle environmental wind tunnel is provided for testing a high - speed rail model. The whole - vehicle environmental wind tunnel includes a fan, a first contraction section, a straight section, a second contraction section, a low - speed nozzle, a test bench, a collector, and a flow channel connected in sequence. The model further includes a high - speed nozzle, a tunnel section, and a diffuser located on the test bench.

[0010] One end of the high - speed nozzle is larger and the other end is smaller. The larger end is connected to the low - speed nozzle, and the smaller end is connected to one end of the tunnel section. One end of the diffuser is larger and the other end is smaller. The larger end is connected to the collector, and the smaller end is connected to the other end of the tunnel section. The high - speed rail model is installed in the tunnel section.

[0011] The diffuser is provided with baffles, and the baffles divide the diffuser into multiple sub - diffusers. The extending direction of the sub - diffusers is the same as that of the diffuser. One end of the sub - diffuser is larger and the other end is smaller, and the larger end is located at the larger end of the diffuser.

[0012] As a preferred technical solution, there are multiple baffles, and the diffusion angle of the sub - diffusers is 7°.

[0013] As a preferred technical solution, the side edges of the baffles close to the collector and the tunnel section are parallel to the air flow direction.

[0014] As a preferred technical solution, the side is connected to the middle of the baffle through an arc.

[0015] As a preferred technical solution, a protrusion is provided on the outer surface of one end of the high-speed nozzle connecting the low-speed nozzle. The low-speed nozzle is sleeved on the outer surface of the high-speed nozzle, and the end face of the low-speed nozzle abuts against the protrusion.

[0016] As a preferred technical solution, the inner wall curve of the end of the high-speed nozzle connected to the low-speed nozzle is tangent to the internal flow passage of the low-speed nozzle; the inner wall curve of the end connected to the tunnel section is the same as the internal flow passage of the tunnel section.

[0017] As a preferred technical solution, the inner wall curve of the high-speed nozzle is two tangent equal-radius curves.

[0018] As a preferred technical solution, the tunnel section includes multiple sub-tunnel sections of equal length. The multiple sub-tunnel sections are sequentially sealed and connected end to end, and noise reduction treatment is carried out.

[0019] As a preferred technical solution, the tunnel section is a three-quarter cylindrical shell.

[0020] As a preferred technical solution, the two ends of the high-speed nozzle are respectively the same as the shapes of the connected low-speed nozzle and the tunnel section; the two ends of the diffuser are respectively the same as the shapes of the connected collector and the tunnel section.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1) Based on the vehicle-mounted environmental wind tunnel, the present invention increases the air flow velocity through the high-speed nozzle, so that the air flow meets the running speed requirements of the high-speed train, and can simulate various complex working conditions such as train meeting and parallel running in the tunnel; through the diffuser, the dynamic pressure of the high-speed flowing air is converted into static pressure, while reducing the impact of the air flow on the deflector and enabling the vehicle-mounted environmental wind tunnel to obtain a certain degree of energy recovery as a whole, reducing the load on the fan; due to size limitations, the lateral and longitudinal diffusion angles of the diffuser will be much larger than the optimal diffusion angle of the diffuser. Therefore, it is divided into multiple sub-diffusers by baffles, so that the diffusion angle of the sub-diffusers can be maintained at the optimal angle.

[0023] 2) At the inlet and outlet of the diffuser, that is, at the position where the side of the baffle is located, the plane of the side of the baffle is parallel to the air flow direction, and the side is connected to the middle of the baffle through an arc, which can reduce the aerodynamic resistance and improve the energy recovery efficiency.

[0024] 3) The low-speed nozzle of the present invention is sleeved on the outer surface of the high-speed nozzle, facilitating the smooth connection of the internal flow channels of the low-speed nozzle and the high-speed nozzle. To ensure the tangency of the curves, the low-speed nozzle is positioned through the design of the protrusion; the inner wall of the high-speed nozzle is designed as a series of smooth and tangent curves, which can divert the airflow to the outlet in a low-resistance state; the use of two tangent equal-radius curves can further reduce the resistance.

[0025] 4) In order to ensure convenient installation and disassembly, the present invention divides the entire tunnel into multiple sub-tunnel segments. The connections between the sub-tunnel segments need to be sealed and sound-absorbing, simulating the operation of a high-speed train in a pipe tunnel / fully enclosed sound barrier. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the overall structure of the vehicle-integrated environmental wind tunnel of the present invention;

[0027] Figure 2 It is a schematic diagram of the overall structure of a high-speed rail tunnel aerodynamic acoustic scale model based on the vehicle-integrated environmental wind tunnel of the present invention;

[0028] Figure 3 It is a schematic diagram of the structure of the high-speed nozzle of the present invention;

[0029] Figure 4 It is a cross-sectional view of the high-speed nozzle of the present invention;

[0030] Figure 5 It is a cross-sectional view after the connection of the high-speed nozzle and the low-speed nozzle of the present invention;

[0031] Figure 6 It is a schematic diagram of a possible inner wall curve structure of the high-speed nozzle of the present invention;

[0032] Figure 7 It is a schematic diagram of the structure of the sub-tunnel segment of the present invention;

[0033] Figure 8 It is a schematic diagram of the structure of the diffuser of the present invention;

[0034] Figure 9 It is a cross-sectional view of the diffuser of the present invention along the horizontal direction;

[0035] Figure 10 It is a cross-sectional view of the diffuser of the present invention along the vertical direction;

[0036] Figure 11 It is a schematic diagram of the velocity distribution at the mid-section position of the second sub-tunnel segment of the present invention;

[0037] Indicated by the reference numerals in the figure:

[0038] 1. First contraction section, 2. Straight section, 3. Second contraction section, 4. Low-speed nozzle, 5. Test bench, 6. Collector, 7. Flow channel, 8. High-speed nozzle, 9. First sub-tunnel section, 10. Second sub-tunnel section, 11. Third sub-tunnel section, 12. Fourth sub-tunnel section, 13. Diffuser, 14. Sub-diffuser, 15. Airflow. Detailed implementation mode

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying 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 embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] The present invention provides a reduced-scale model of a high-speed rail tunnel aerodynamic acoustics based on a full-vehicle environmental wind tunnel for testing a high-speed rail model, based on a full-vehicle environmental wind tunnel (CWT, Climatic Wind Tunnel). The problems to be solved by the present invention are to overcome the technical problems such as the insufficient aspect ratio of the existing thermal environmental wind tunnel, the test wind speed not being sufficient to reach the train operation condition, and the distortion of the inlet wind speed. If the tunnel model is directly connected through the low-speed nozzle 4, there will be problems such as insufficient wind speed, serious jet effect after the tunnel exit (which may damage the deflector of the wind tunnel collection port), and installation difficulties. By designing a series of components to modify the test section of the CWT (Climatic Wind Tunnel, full-vehicle thermal environmental wind tunnel), its operating flow field is changed, the maximum wind speed is increased, the high-speed rail operation speed requirements are met, and various complex conditions such as passing by and running parallel of trains in the tunnel are simulated.

[0041] As Figure 1 shown, the full-vehicle environmental wind tunnel includes a fan, a first contraction section 1, a straight section 2, a second contraction section 3, a low-speed nozzle 4, a test bench 5, a collector 6, and a flow channel 7 connected in sequence. Under the action of the fan, the airflow 15 (in the direction of the arrow) enters the first contraction section 1 at a certain initial speed, is preliminarily diverted and accelerated through the straight section 2, then enters the second contraction section 3, and after further contraction and acceleration, it is ejected from the low-speed nozzle 4 and passes through the test bench 5 where the object to be measured can be placed. The surrounding flow field and various aerodynamic characteristic parameters can be accurately measured on the test bench 5. The airflow 15 enters the collector 6 after passing through the test bench 5. A deflector is provided at the corner of the collector 6 to deflect the incoming airflow 15 to the vertical direction. After being deflected by the collector 6, the airflow 15 flows out from the flow channel 7 and is recycled by the wind tunnel.

[0042] As Figure 2 shown, the present invention further includes a high-speed nozzle 8, a tunnel section, and a diffuser 13 installed on the test bench 5.

[0043] AsFigure 3 and Figure 4 As shown in Figure 4 , the high-speed nozzle 8 has a certain compression ratio and a series of smooth curves, which can divert the air flow 15 to the outlet in a low-resistance state, increase the flow velocity of the air flow 15, and divert the flow cross-section from a rectangle to a tunnel section. One end of the high-speed nozzle 8 is larger and the other end is smaller. The larger end is connected to the low-speed nozzle 4, and a protrusion is provided on the outer surface of this end. The low-speed nozzle 4 is sleeved on the outer surface of the high-speed nozzle 8, and the end face of the low-speed nozzle 4 abuts against the protrusion. The smaller end is connected to one end of the tunnel section, and the diameter gradually decreases from the protrusion. When the wind tunnel is started, under the action of the fan, the air flow 15 enters the high-speed nozzle 8 after passing through the first contraction section 1, the straight section 2, the second contraction section 3, and the low-speed nozzle 4. The inlet of the high-speed nozzle 8 is a rectangle corresponding to the low-speed nozzle 4, and the outlet is a tunnel cross-section type corresponding to the tunnel section. There is a certain compression ratio between the two cross-sections, which can further divert and accelerate the air flow 15.

[0044] To reduce resistance and improve the uniformity of the flow field, the inner wall of the high-speed nozzle 8 is designed as a series of smooth and tangent curves, which can divert the air flow 15 to the outlet in a low-resistance state, as Figure 6 shown. The inner wall curve of the high-speed nozzle 8 can be designed as two tangent equal-radius curves. As Figure 5 shown, the inner wall curve of the high-speed nozzle 8 is in contact with and tangent to the wall surface of the low-speed nozzle 4, which can reduce aerodynamic resistance and energy loss, and improve the uniformity of the flow field. After the air flow 15 is diverted, accelerated and ejected by the high-speed nozzle 8, it enters the tunnel section at an extremely high speed.

[0045] As Figure 7 shown, the cross-section of the tunnel section is completely fitted with the outlet surface of the high-speed nozzle 8, and both are scaled-down models of the high-speed rail tunnel cross-section, which are used to simulate the real tunnel environment; during the test, the scaled high-speed rail model can be installed in the tunnel section for testing.

[0046] To ensure convenient installation and disassembly, the entire tunnel is divided into four equal-length sub-tunnel sections: the first sub-tunnel section 9, the second sub-tunnel section 10, the third sub-tunnel section 11, and the fourth sub-tunnel section 12. The sub-tunnel sections are connected end to end in sequence, and the connection between adjacent sub-tunnel sections needs to be sealed and sound-proofed to simulate the operation of a high-speed train in a pipe tunnel / full-enclosed sound barrier. The high-speed rail model is installed inside the tunnel section.

[0047] As Figure 8As shown, the diffuser 13 has a larger end and a smaller end. The larger end is connected to the collector 6, and the smaller end is connected to the other end of the tunnel section. When the gas flows in from the inlet, the cross-sectional area increases, the velocity gradually decreases, and the pressure gradually increases. The air flow 15 flows against the pressure gradient. During this process, the kinetic energy of the air flow 15 decreases, and this part of the kinetic energy is converted into the static pressure of the air flow 15. The diffuser 13 can prevent the high-speed air flow 15 from directly impacting the deflector in the collector 6 after flowing out of the tunnel section, causing high-intensity and uneven loads that damage the structure. At the same time, it converts the dynamic pressure of the high-speed air flow 15 into static pressure, achieving a certain degree of energy recovery and reducing the load on the wind tunnel fan.

[0048] Due to the dimensional limitation of the length of the test bench 5, the length remaining for the installation of the diffuser 13 after installing the tunnel section is small. To transition from a small cross-section to a large cross-section within a short distance, the lateral and longitudinal diffusion angles of the diffuser 13 will be much larger than the optimal diffusion angle of the diffuser. Therefore, baffles are provided inside the diffuser 13. The baffles divide the diffuser 13 into multiple sub-diffusers 14. For different structures, different baffle distribution methods can be adopted, such as Figure 9 and Figure 10 As shown, the diffusion angle of the sub-diffuser 14 is maintained at about 7°. When the diffusion angle is maintained at about 6 - 7°, the efficiency of converting its dynamic pressure into static pressure is the highest.

[0049] At the inlet and outlet of the diffuser 13, the side plane of the baffle is parallel to the direction of the air flow 15, and the side is connected to the middle of the baffle through an arc. The air flow 15 undergoes an arc transition. This design can reduce the aerodynamic resistance and improve the energy recovery efficiency. The high-speed air flow 15 enters the collector 6 after decelerating and expanding through the diffuser 13, and then flows out through the flow channel 7 after being diverted by it, and is recycled by the wind tunnel to reduce the load on the fan.

[0050] Using the Star ccm+ software, numerical simulation calculations were carried out on the constructed model based on the existing wind tunnel model. The specific structural parameters of each component are shown in Table 1.

[0051] Table 1 Structural parameters of each component of the model

[0052]

[0053]

[0054] Such as Figure 11 As shown, at the midpoint cross-section of the second sub-tunnel section 10, its maximum wind speed reaches 146 m / s (about 520 Km / h), and the average wind speed is 143.6 m / s (about 515 Km / s), meeting the train operation speed. After calculation, the relative standard deviation of the speed at the midpoint cross-section of the second sub-tunnel section 10 is lower than 6%, and the uniformity is good.

[0055] The present invention can increase the wind speed in the vehicle environment wind tunnel test section to reach the high-speed rail operation speed. Combining with the advantages of CWT itself, it can study the parallel working conditions of the tunnel and high-speed rail more comprehensively, accurately and controllably, carry out highly repetitive and systematic high-speed rail tunnel aerodynamic acoustics experiments at a relatively low cost, and fill the gap in the high-speed rail tunnel aerodynamic acoustics experiments in the ground vehicle wind tunnel.

[0056] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A pneumoacoustic scale model of a high-speed rail tunnel based on a full vehicle environmental wind tunnel, which is used to test a high-speed rail model. The full vehicle environmental wind tunnel includes a fan, a first contraction section (1), a straight section (2), a second contraction section (3), a low-speed nozzle (4), a test bench (5), a collector (6) and a flow channel (7) connected in sequence. It is characterized in that, The model also includes a high-speed nozzle (8), a tunnel section, and a diffuser (13) located on the test bench (5); One end of the high-speed nozzle (8) is larger and the other end is smaller. The larger end is connected to the low-speed nozzle (4), and the smaller end is connected to one end of the tunnel section. One end of the diffuser (13) is larger and the other end is smaller. The larger end is connected to the collector (6), and the smaller end is connected to the other end of the tunnel section. The high-speed train model is installed inside the tunnel section; A baffle is provided inside the diffuser (13). The baffle divides the diffuser (13) into multiple sub-diffusers (14). The extending direction of the sub-diffusers (14) is the same as that of the diffuser (13). One end of the sub-diffuser (14) is larger and the other end is smaller. The larger end is located at the larger end of the diffuser (13).

2. The aerodynamic acoustic scaled model of a high-speed railway tunnel based on the vehicle environment wind tunnel according to claim 1, wherein There are multiple such baffles, and the diffusion angle of the sub-diffusers (14) is 7°.

3. The aerodynamic acoustic scale model of a high-speed rail tunnel based on the vehicle environment wind tunnel according to claim 1, characterized in that The sides of the baffle close to the collector (6) and the tunnel section are parallel to the direction of the air flow (15).

4. The aerodynamic acoustic scale model of a high-speed rail tunnel based on the vehicle environment wind tunnel according to claim 3, characterized in that The sides are connected to the middle of the baffle through an arc.

5. A reduced-scale model of aerodynamic acoustics for high-speed railway tunnels based on the vehicle's overall environment wind tunnel, characterized in that, A protrusion is provided on the outer surface of the end of the high-speed nozzle (8) connected to the low-speed nozzle (4). The low-speed nozzle (4) is sleeved on the outer surface of the high-speed nozzle (8), and the end face of the low-speed nozzle (4) abuts against the protrusion.

6. The aerodynamic acoustic scale model of a high-speed railway tunnel based on a full vehicle environmental wind tunnel according to claim 1, characterized in that The inner wall curve of the end of the high-speed nozzle (8) connected to the low-speed nozzle (4) is tangent to the internal flow channel (7) of the low-speed nozzle (4); the inner wall curve of the end connected to the tunnel section is the same as the internal flow channel (7) of the tunnel section.

7. A reduced-scale model of aerodynamic acoustics for high-speed railway tunnels based on the vehicle environment wind tunnel according to claim 6, characterized in that The inner wall curve of the high-speed nozzle (8) is two tangent equal-radius curves.

8. The aerodynamic acoustic scaled model of a high - speed rail tunnel based on the vehicle - level environmental wind tunnel according to claim 1, wherein The tunnel section includes multiple sub-tunnel sections of equal length. The multiple sub-tunnel sections are sequentially and hermetically connected end to end and are subjected to sound absorption treatment.

9. The aerodynamic acoustic scale model of a high-speed rail tunnel based on a full vehicle environmental wind tunnel according to claim 1, characterized in that, The tunnel section is a three-quarter cylindrical shell.

10. A reduced-scale model of aerodynamic acoustics for a high-speed railway tunnel based on a full-vehicle environmental wind tunnel, characterized in that, The two ends of the high-speed nozzle (8) are respectively the same shape as the low-speed nozzle (4) and the tunnel section connected thereto; the two ends of the diffuser (13) are respectively the same shape as the collector (6) and the tunnel section connected thereto.

Images