A method for alleviating aerodynamic effects in tunnels with variable cross-section and heating coupling

Abstract

A method for alleviating aerodynamic effects of a tunnel coupled with variable cross-section and heating comprises the following steps: a. arranging an expansion section at the entrance and exit of a tunnel, wherein the expansion section is formed by the inner diameter of the tunnel entrance and exit being larger than the inner diameter of a middle section; b. arranging heating zones for heating the air in the tunnel in the tunnel with the tunnel entrance and exit as starting ends, wherein the heating zones in the tunnel are divided into a plurality of continuously arranged heating zones along the length direction of the tunnel, and each heating zone can be individually controlled to open and close. The present invention improves the effect of alleviating aerodynamic effects through the cooperation of variable cross-section and heating, and enables the aerodynamic effects of high-speed trains to meet relevant environmental assessment standards.

Description

Technical Field

[0001] The invention relates to a method for alleviating aerodynamic effects of a tunnel with variable cross-section and heating coupling. Background Art

[0002] The aerodynamic effect when a high-speed train passes through a tunnel refers to the fact that when the train enters the tunnel, a huge piston effect is generated, causing the air in front of the train to be violently squeezed to form a compression wave. The compression wave is transmitted to the tunnel exit to form a micro-air pressure wave, which is further intensified to become an air pressure explosion wave. On the one hand, the air pressure explosion wave emits a violent noise, causing environmental pollution and causing serious trouble to the lives of residents around the tunnel entrance. On the other hand, the drastic changes in the pressure waves in the tunnel acting on the car body and the tunnel surface will also affect the safety of train operation, and may even damage the car body structure and tunnel facilities. The pressure outside the car will also cause discomfort to the passengers when it is transmitted to the car, seriously affecting the comfort of the passengers. Since the size of the pressure wave in the tunnel mainly depends on the blockage ratio (the ratio of the cross-sectional area of ​​the train to the cross-sectional area of ​​the tunnel), the maximum value of the micro-air pressure wave outside the tunnel is positively correlated with the initial compression wave pressure gradient. Therefore, in the prior art, there are two solutions to alleviate the aerodynamic effect of the tunnel using the above principle:

[0003] 1. For micro-pressure waves, it is usually considered to set up a buffer structure (such as auxiliary facilities such as vertical shafts, inclined shafts or horizontal tunnels) to reduce the transient pressure in the tunnel, which is a relatively economical and effective method. At present, the buffer facilities for reducing micro-pressure waves include various new types of oblique tunnel portals or internal step-type buffer structures. At the same time, the initial compression wave pressure gradient is reduced by lengthening the streamlined length of the train, but the effect of reducing the maximum value of the compression wave is not obvious. Vertical shafts and inclined shafts can reduce the pressure fluctuations in the tunnel and alleviate the micro-pressure waves outside the tunnel. However, the positions of the vertical shafts and inclined shafts for relieving pressure fluctuations and micro-pressure waves are different. The same vertical shaft cannot play the best role in relieving pressure fluctuations and micro-pressure waves. Moreover, most of the vertical shafts, inclined shafts or horizontal tunnels are designed for ventilation, rescue or measures that are forced to be taken under the constraints of terrain conditions, so the effect of their design parameters on alleviating aerodynamic effects is limited.

[0004] 2. Use a variable cross-section tunnel structure, such as the application number: 201810416498.8, the invention name is: Variable cross-section tunnel structure and parameter determination method for alleviating tunnel aerodynamic effect, which discloses a variable cross-section tunnel structure by setting an expansion section at the entrance and exit of the tunnel, thereby alleviating the tunnel aerodynamic effect. At present, the main operating speed of my country's high-speed trains is 350km / h, but in the future, the operating speed of trains will be increased to 400km or higher, and the speed of high-speed maglev will reach 600km / h or higher. The pressure fluctuation in the tunnel is proportional to the square of the speed, and the air pressure explosion wave stimulated by micro-air pressure is 6-13 times the speed of the vehicle. Therefore, when the speed increases, the aerodynamic effect will show a dramatic increase. If we only rely on the variable cross-section of the entrance and exit, the area of ​​the expanded section will become very large, which will bring huge construction costs. For example, the cross-sectional area of ​​a 100-square-meter tunnel is 1.4 times that of a 70-square-meter tunnel, but the construction cost is twice as much. As the cross-section of the tunnel increases, the span of the tunnel will increase, and the requirements for the supporting structure of the tunnel will also increase, greatly increasing the cost, and it is difficult to increase the cross-sectional area indefinitely. Summary of the invention

[0005] The present invention solves the deficiencies of the prior art and provides a method for alleviating the aerodynamic effect of a tunnel by combining heating and a variable cross-section and heating.

[0006] To achieve the above object, the present invention first proposes a method for alleviating aerodynamic effects of a tunnel with variable cross-section and heating coupling, comprising the following steps:

[0007] a. Arrange an expansion section at the entrance and exit of the tunnel, wherein the inner diameter of the tunnel entrance and exit is larger than the inner diameter of the middle section;

[0008] b. In the tunnel, heating zones for heating the air in the tunnel are respectively arranged with the tunnel entrance and exit as the starting end. The heating zones in the tunnel are divided into a plurality of continuously arranged heating sections along the length direction of the tunnel, and each heating section can be individually controlled to open and close.

[0009] With the above structure, firstly, the expansion section is arranged at the entrance and exit of the tunnel, which has been verified to have the effect of alleviating the aerodynamic effect of the tunnel. However, as the running speed of the high-speed train continues to increase, the pressure fluctuation in the tunnel is proportional to the square of the speed, and the air pressure explosion wave stimulated by the micro-air pressure is the 6-13th power of the vehicle speed, and the aerodynamic effect will show a dramatic increase. If the aerodynamic effect is alleviated only by relying on variable cross-section, the area of ​​the expansion section will become very large. Whether it can be achieved or not will at least bring great construction costs. For example, the cross-sectional area of ​​a tunnel of 100 square meters is 1.4 times that of a 70-square-meter plane, but the construction cost is 2 times, and it is difficult to increase the cross-sectional area of ​​the tunnel without limit. Therefore, the present invention cooperates with variable cross-section and heating, and the heating zone starts at the tunnel entrance. Before the train enters the tunnel, the heating zone is started to heat the air in the tunnel to a certain temperature. Since the pressure wave amplitude is composed of two parts: the piston effect and the friction between the train and the air. When the air temperature in the tunnel rises, the air density decreases. At this time, the piston effect when the train enters the tunnel is weakened. At the same time, the friction effect between the train and the air will also be weakened, resulting in a decrease in the amplitude of the pressure wave. The amplitude of the micro-pressure wave is positively correlated with the initial compression wave pressure gradient. When the air density decreases, the interaction between the train and the air when entering the tunnel is reduced, and the initial compression wave pressure gradient will also decrease, thereby reducing the amplitude of the micro-pressure wave. Therefore, by increasing the temperature of the tunnel by heating the zone, the aerodynamic effect in the tunnel can be alleviated. Since the tunnel pressure wave and micro-pressure wave are mainly formed at the entrance section of the tunnel, the middle section of the tunnel mainly affects the propagation speed of the pressure wave. At the end of the tunnel, the pressure will be emitted in this area, which will affect the size of the pressure wave. Therefore, the heating zone starts from the tunnel entrance to ensure that the aerodynamic effect in the tunnel is best alleviated. In addition, since each heating section can be controlled to open and close individually, by opening different numbers of heating sections, it can adapt to trains of different lengths, achieve precise heating, and improve energy efficiency.

[0010] In this embodiment, in step a, the expansion sections of the tunnel entrance and exit are symmetrically distributed, and the ratio of the cross-sectional area of ​​the tunnel expansion section to the cross-sectional area of ​​the tunnel middle section is called the expansion coefficient, and the expansion coefficient ranges from 1.05 to 1.2. Assume that the length of the expansion section D 扩 , the total length of the tunnel is D 总 , D 扩 =(0.2-0.26)D 总 .

[0011] In this embodiment, the total length of the heating section in the tunnel starting from the heating section at the tunnel entrance and continuously opened is the same as the streamlined length of the train head to pass through the tunnel or the same as the length of the train body. With the above structure, if only the micro-air pressure wave outside the tunnel needs to be alleviated, only the heating area with the same length as the streamlined length of the train head can be arranged in the tunnel. If the pressure fluctuation in the tunnel and the micro-air pressure wave outside the tunnel need to be alleviated at the same time, the length of the heating area is the same as the length of the train body, so that the energy consumption can be minimized according to the demand to achieve the effect of alleviating the aerodynamic effect.

[0012] In this embodiment, the heating zones at both ends of the tunnel are opened simultaneously, so that the aerodynamic effect is further alleviated.

[0013] In this embodiment, a heating device is arranged on each heating section, a temperature monitoring system is installed in the tunnel, the heating device and the temperature monitoring system are connected to the control system, the temperature monitoring system monitors the temperature of the heating zone in the tunnel in real time, and the control system controls the start and stop time of the heating device according to the real-time arrival time of the train and the temperature to be reached in the tunnel. Through the control system, the heating device is started when the train arrives, and the heating device is turned off when the train passes, thereby reducing energy consumption.

[0014] In this embodiment, before the train arrives at the tunnel, the heating section heats the air in the tunnel to 50° C. to 100° C. The higher the temperature, the better the aerodynamic effect mitigation effect, and the heating time can be selected according to the external temperature.

[0015] In this embodiment, the heating device is a heating plate with a thickness of no more than 2 mm, and the heating plate is fixed on the inner wall of the tunnel. In this way, when the heating device is installed, the influence on the inner diameter of the tunnel can be reduced, thereby improving the aerodynamic effect mitigation effect.

[0016] In summary, the present invention solves the problem that the current traditional variable cross-section aerodynamic effect mitigation method has limited mitigation effect and can only alleviate a single pressure fluctuation in the tunnel or a micro-pressure wave outside the tunnel. A method for mitigating the aerodynamic effect of a tunnel coupled with variable cross-section and heating is proposed. Through the coordination of variable cross-section and heating, the aerodynamic effect under the operating conditions of a higher-speed train can meet the relevant environmental impact assessment standards, achieve safe operation, and effectively improve the comfort of residents around the tunnel entrance and passengers in the car. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the external structure diagram of the tunnel of the present invention.

[0018] Figure 2 It is a layout diagram of the circumferential direction of the heating zone tunnel of the present invention.

[0019] Figure 3It is a relationship diagram between the pressure wave relief rate and the circumferential layout area of ​​the heating zone of the present invention.

[0020] Figure 4 It is a relationship diagram between the pressure wave relief rate and the streamlined length of the train head according to the present invention.

[0021] Figure 5 It is a trend diagram of the wave relief rate in the tunnel in the first group of experiments of the present invention.

[0022] Figure 6 It is a trend diagram of the wave relief rate in the tunnel in the second group of experiments of the present invention.

[0023] Figure 7 It is a trend diagram of the wave relief rate in the tunnel in the third group of experiments of the present invention.

[0024] In the accompanying drawings, 1 is the expansion section, 2 is the heating zone. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0027] The present invention provides a method for alleviating aerodynamic effects of a tunnel with variable cross-section and heating coupling, comprising the following steps:

[0028] a. Figure 1 As shown, the expansion sections are arranged at the entrance and exit of the tunnel. The expansion sections of the entrance and exit of the tunnel are symmetrically distributed. The ratio of the cross-sectional area of ​​the tunnel expansion section to the cross-sectional area of ​​the middle section of the tunnel is called the expansion coefficient. The expansion coefficient ranges from 1.05 to 1.2. Assume that the length of the expansion section D 扩 , the total length of the tunnel is D 总 , D 扩 =(0.2-0.26)D 总 ;

[0029] b. In the tunnel, a heating zone for heating the air in the tunnel is set up with the tunnel entrance and exit as the starting end. The heating zone in the tunnel is divided into a plurality of continuously arranged heating sections along the length direction of the tunnel. Each heating section can be controlled to open and close separately. The heating zone is symmetrically arranged with the center of the tunnel top as the symmetry axis, and the heating zone is arranged 220° along the circumference of the tunnel. In this embodiment, the total length of the heating section in the tunnel starting from the heating section at the tunnel entrance and continuously opened is the same as the streamlined length of the train head to pass through the tunnel or the same as the length of the train body. A heating device is arranged on each heating section. A temperature monitoring system is installed in the tunnel. The heating device and the temperature monitoring system are connected to the control system. The temperature monitoring system monitors the temperature of the heating zone in the tunnel in real time. The control system controls the opening and closing time of the heating device according to the real-time arrival time of the train and the temperature to be reached in the tunnel. Through the control system, the heating device is started when the train comes, and the heating device is turned off after the train leaves, thereby reducing energy consumption. The temperature to be reached in the tunnel is 50℃~100℃. The higher the temperature, the better the aerodynamic effect mitigation effect. The heating temperature can be selected according to the outside temperature and actual energy conditions.

[0030] Embodiment 1:

[0031] Take a double-decker high-speed train as an example, the streamlined length of the train head is 12.5m, the total length of the train body is 83m, and the train speed is 350km / h. Assuming the tunnel length is 350m, the ratio of the length of the expanded section to the total length of the tunnel is 0.26, and the length of the expanded section distributed at both ends of the tunnel is 91m.

[0032] like Figure 2 This is the structural diagram when the circumferential layout angle of the heating zone in the tunnel is 260° and 220°. The length of the heating zone in the expanded section is 12.5m, which is the same as the streamlined length of the train head. The heating target temperature is set to 60℃, and the circumferential layout angle of the heating zone in the tunnel is divided into 12 different angles. Micro-pressure wave measurement points are set outside the tunnel at 20m and 50m away from the tunnel exit, and the micro-pressure wave amplitudes at different heating angles are obtained, as shown in the following table.

[0033] Table 1 Micro-pressure amplitude at different heating angles

[0034]

[0035] From Table 1, we can conclude Figure 3 ,It can be seen that when the heating angle is 220°, the mitigation effect is very close to 100%, so the circumferential arrangement angle of the heating zone in the tunnel is 220° ~ 260° to achieve a better heating effect.

[0036] Embodiment 2:

[0037] Take a double-decker high-speed train as an example. The streamlined length of the train head is 12.5m, the total length of the train body is 83m, and the train speed is 350km / h. Assume that the tunnel length is 1000m, the ratio of the length of the expansion section to the total length of the tunnel is 0.26, and the length of the expansion section distributed at both ends of the tunnel is 260m. The circumferential layout angle is 220°. Set the heating target temperature to 60℃.

[0038] Pressure wave measurement points were set in the tunnel, and the data in Table 2 were obtained:

[0039] Table 2 Maximum values ​​of pressure waves at room temperature and different heating zone lengths

[0040] normal temperature 0.5 times vehicle length heating area 1 times vehicle length heating area Heating area twice the vehicle length Pressure wave value 2496Pa 2416Pa 2272Pa 2280Pa

[0041] Micro pressure wave measuring points were set outside the tunnel at 20m and 50m away from the tunnel exit, and the data in Table 3 were obtained:

[0042] Table 3 Maximum values ​​of micro pressure waves under normal temperature and different heating section opening lengths

[0043]

[0044] As shown in Table 2, it is the change of pressure wave value when the length of heating zone is related to the length of train body, and Table 3 is the change of micro pressure wave when the length of heating zone is related to the streamline length of train head. It can be seen from the above table that when the length of heating section is 1 times of train length, the pressure wave value is the best value under this set of conditions, and when the length of heating section is 1 times of streamline length of train head, the micro pressure wave is the best value under this set of conditions. The contents in Table 3 are used Figure 4 To show, Figure 4 Point A represents the length of the heating section opened, which is 0.5 times the streamlined length of the train head; point B represents the length of the heating section opened, which is 1 times the streamlined length of the train head; point C represents the length of the heating section opened, which is 2 times the streamlined length of the train head. Figure 4 From the intuitive representation, it can be concluded that the aerodynamic relief effect is best when the opening length of the heating section is consistent with the train length or the streamlined length of the train head.

[0045] According to the above analysis, the length of the heating section is set to be consistent with the length of the train body, and the length of the tunnel is divided into 18 sections, with a measurement point set in each section:

[0046] The first set of tests was to lay out the heating zone starting from the tunnel entrance.

[0047] The second group of tests was conducted by arranging the heating zone with the middle of the tunnel as the starting point.

[0048] The third group of tests was conducted by arranging the heating zone with the tunnel exit as the starting point.

[0049] The normal temperature pressure and heating pressure of each measuring point in the first, second and third groups of tests were calculated respectively, and then the pressure wave relief rate at different positions of the tunnel in each group of tests was obtained. Figure 5 , 6 ,7,In the figure, the dimensionless length refers to the ratio of the distance from the measuring point in the tunnel to the tunnel entrance to the tunnel length.

[0050] according to Figure 5 , 6 7. It can be seen that in the first group of tests, when the heating zone is arranged with the tunnel entrance as the starting point, the pressure wave relief effect is the best. In the second group of tests, when the heating zone is arranged with the middle of the tunnel as the starting point, there is basically no relief effect on the pressure wave. In the third group of tests, when the heating zone is arranged with the tunnel exit as the starting point, some areas in the tunnel also have a certain relief effect. Therefore, it can be concluded that the heating zone needs to be arranged with the tunnel entrance as the starting point. If energy consumption is not considered, the heating devices at both ends of the tunnel can be turned on at the same time for better relief effect.

[0051] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for alleviating aerodynamic effects of a tunnel with variable cross-section and heating coupling, characterized in that: The steps include: a. Arrange an expansion section at the entrance and exit of the tunnel. The expansion section is formed by the inner diameter of the tunnel entrance and exit being larger than the inner diameter of the middle section. The expansion sections of the tunnel entrance and exit are symmetrically distributed. The ratio of the cross-sectional area of ​​the tunnel expansion section to the cross-sectional area of ​​the tunnel middle section is called the expansion coefficient. The expansion coefficient ranges from 1.05 to 1.

2. Assume that the length of the expansion section is D 扩 , the total length of the tunnel is D 总 , D 扩 = (0.2-0.26) D 总 ; b. In the tunnel, heating zones for heating the air in the tunnel are respectively arranged with the tunnel entrance and exit as the starting end. The heating zones in the tunnel are divided into a plurality of continuously arranged heating sections along the length direction of the tunnel. Each heating section can be individually controlled to open and close. The heating zones are symmetrically arranged with the center of the tunnel top as the symmetry axis, and the heating zones are arranged 220° along the circumference of the tunnel.

2. The method for alleviating aerodynamic effects of a tunnel with variable cross-section and heating coupling as claimed in claim 1, characterized in that: In step b, the total length of the heating sections in the tunnel starting from the heating section at the tunnel entrance and continuously opened is the same as the streamlined length of the front of the train to pass through the tunnel or the same as the length of the train body.

3. The method for alleviating aerodynamic effects of a tunnel with variable cross-section and heating coupling as claimed in claim 2, characterized in that: The heating zones at both ends of the tunnel are turned on simultaneously.

4. The method for alleviating aerodynamic effects of a tunnel with variable cross-section and heating coupling as claimed in claim 3, characterized in that: A heating device is arranged on each heating section, and a temperature monitoring system is installed in the tunnel. The heating device and the temperature monitoring system are connected to a control system. The temperature monitoring system monitors the temperature of the heating zone in the tunnel in real time, and the control system controls the start and close time of the heating device according to the real-time arrival time of the train and the temperature to be reached in the tunnel.

5. The method for alleviating aerodynamic effects of a tunnel with variable cross-section and heating coupling as claimed in claim 4, characterized in that: Before the train arrives at the tunnel, the heating section heats the air in the tunnel to 50°C to 100°C.

6. The method for alleviating aerodynamic effects of a tunnel with variable cross-section and heating coupling as claimed in claim 5, characterized in that: The heating device is a heating plate with a thickness not greater than 2 mm, and the heating plate is fixed on the inner wall of the tunnel.

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