Pneumatic determination method and system for clearance area of high-speed maglev traffic tunnel

Abstract

The invention relates to the technical field of aerodynamic design of high-speed rail transit tunnels, and discloses a high-speed maglev traffic tunnel clearance area pneumatic determination method and system, and the method comprises the steps: obtaining an external pressure time travel curve of a high-speed maglev train when the high-speed maglev train passes through a tunnel at a preset running speed; calculating an in-vehicle pressure time history curve based on the out-vehicle pressure time history curve and the whole vehicle time constant; recognizing the most unfavorable working condition which plays a decisive role in the design of the clearance area of the tunnel according to a composite comfort standard; determining a tunnel clearance area required to meet a single limit value through iterative solution under the most unfavorable working condition; and determining the final minimum tunnel clearance area from all the single-index tunnel clearance areas. The system comprises a pressure acquisition module, a pressure calculation module, a working condition identification module, an area iteration module and an area determination module. According to the method, the tunnel clearance area design which is economical and reasonable and meets the comfort requirement can be realized, and a related mapping database is established to provide guidance for engineering design.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-speed rail transit tunnel aerodynamics design, in particular to a method and system for determining the clearance area aerodynamics of a high-speed maglev transit tunnel. BACKGROUND

[0002] As a representative of the new generation of rail transit, the high-speed maglev train has a super-high-speed running characteristic, which makes the aerodynamic effect induced when the train passes through the tunnel far exceed that of the traditional wheel-rail train. In particular, the rapid pressure fluctuation caused by the transmission of tunnel pressure waves to the train compartment seriously affects the ear comfort of passengers, and causes physiological reactions such as ear congestion, ear pain, and tinnitus, which becomes a key factor restricting the riding experience.

[0003] Currently, the industry mainly uses two ways to alleviate this problem: one is to increase the tunnel clearance area to reduce the strength of the aerodynamic effect; the other is to improve the air tightness of the vehicle in the case of limited tunnel clearance area. However, each of these two methods has its own limitations. Simply increasing the tunnel clearance area can effectively improve comfort, but it significantly increases the cost of tunnel construction, which is not cost-effective. Excessive reliance on high air tightness of the vehicle can compensate for the lack of tunnel area to some extent, but the vehicle manufacturing process is complex, and compromises still need to be made in terms of tunnel clearance area. The existing technology often lacks systematic consideration of the complex coupling relationship between the air tightness of the vehicle, various comfort standards, and the length of the tunnel when determining the tunnel clearance area. Specifically, the existing methods fail to provide an effective way to comprehensively weigh and accurately match the relationship between the air tightness of the vehicle, comfort standards, and the length of the tunnel, as the demand for tunnel clearance area varies for different time-scale comfort indicators (such as short-term pressure change rate and total pressure change extreme value), and the aerodynamic effect has the "worst" performance under different tunnel lengths. Therefore, how to scientifically build the optimal matching relationship between the air tightness of the vehicle, comfort standards, and the tunnel clearance area, so as to achieve economic rationality of engineering construction under the premise of meeting passenger comfort, is a key technical problem that needs to be solved in the current high-speed maglev transportation field.

[0004] Therefore, the present application proposes a method and system for determining the clearance area aerodynamics of a high-speed maglev transit tunnel to solve the deficiencies of the prior art. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a method and system for determining the clearance area aerodynamics of a high-speed maglev transit tunnel, which solves the problem that it is difficult to comprehensively consider all potential worst-case conditions under the composite comfort standard when determining the clearance area of a high-speed maglev transit tunnel, which may result in a conservative design or a comfort risk.

[0006] To solve the above technical problems, the application provides a closed-loop determination method and system for coupling the air tightness of a vehicle body, a composite comfort standard and tunnel geometric parameters, which can identify multiple most unfavorable working conditions controlled by different comfort indicators and iteratively solve the minimum tunnel clearance area that meets all constraint conditions on this basis.

[0007] The first aspect of the application provides a high-speed maglev tunnel clearance area aerodynamic determination method, which comprises: First, obtain the time history curve of the external pressure of a high-speed maglev train passing through a tunnel at a preset running speed. This step can be calculated using a one-dimensional compressible unsteady non-isentropic flow model or a three-dimensional computational fluid dynamics simulation method. When using a one-dimensional compressible unsteady non-isentropic flow model, the corresponding pressure loss coefficient is introduced according to the specific shape of the train, the marshalling mode and the blockage ratio of the train and the tunnel, so as to simulate the influence of complex train shape and blockage ratio on external pressure in the calculation.

[0008] Secondly, based on the obtained time history curve of the external pressure and the preset whole vehicle time constant, the time history curve of the internal pressure is calculated. This calculation step is specifically: taking the time history curve of the external pressure and the whole vehicle time constant as input, and performing time step by step recursive calculation through the following formula: ; In the formula, Pn is the internal pressure at the next time, Pn-1 is the internal pressure at the current time, Pn-1 is the pressure value on the time history curve of the external pressure at the current time, is the whole vehicle time constant, is the time step. The whole vehicle time constant can be determined by a static pressure relief test on a specific train, specifically the time required for the internal pressure to naturally decrease from a preset high pressure value to a preset low pressure value.

[0009] Then, according to the preset composite comfort standard, multiple most unfavorable working conditions are identified. The composite comfort standard includes the limitation of the pressure change amount in multiple different time intervals and the pressure change extreme value in any time. This identification step first compares the pressure change amount of all carriages of the train calculated according to the time history curve of the internal pressure to determine the most unfavorable carriage with the largest pressure change amount. Then, for the most unfavorable carriage, a critical tunnel length is determined for each limited value in the composite comfort standard, which makes the pressure change amount corresponding to the limited value reach the maximum, so as to identify multiple most unfavorable working conditions controlled by different comfort indicators respectively.

[0010] Then, in the working condition constituted by each of the limit value and the critical tunnel length corresponding thereto, a single-index tunnel clearance area required to meet the limit value is solved by iteratively adjusting the tunnel clearance area. The solving step specifically comprises: taking the limit value as a convergence target, comparing the calculated pressure change with the convergence target in each iteration, and adjusting the tunnel clearance area value in the next iteration according to the comparison result, and the process is repeated until the difference between the calculated pressure change and the convergence target meets a preset convergence criterion.

[0011] Finally, the maximum value of all the solved single-index tunnel clearance areas is taken as the minimum tunnel clearance area meeting the composite comfort standard. This step is specifically completed by the following formula: ; In the formula, is the minimum tunnel clearance area, is the single-index tunnel clearance area required by the i-th limit value at the critical tunnel length corresponding thereto, is the total number of limit values included in the composite comfort standard.

[0012] After the above steps are completed, the method can further comprise: establishing a mapping database between the composite comfort standard, the critical tunnel length, the whole vehicle time constant and the finally determined minimum tunnel clearance area.

[0013] The second aspect of the present application provides a high-speed maglev tunnel clearance area aerodynamic determination system, which comprises: A pressure acquisition module is configured to acquire an external pressure time history curve of a high-speed maglev train passing through a tunnel at a preset running speed. A pressure calculation module is configured to calculate an internal pressure time history curve based on the external pressure time history curve and a preset whole vehicle time constant. A working condition identification module is configured to calculate a plurality of pressure changes corresponding to the internal pressure time history curve according to a plurality of limit values included in a preset composite comfort standard, and determine a critical tunnel length for each limit value that maximizes the corresponding pressure change. An area iteration module is configured to iteratively adjust the tunnel clearance area to solve a single-index tunnel clearance area required to meet each limit value in the working condition constituted by each limit value and the critical tunnel length corresponding thereto. An area determination module is configured to take the maximum value of all the solved single-index tunnel clearance areas as the minimum tunnel clearance area meeting the composite comfort standard.

[0014] ​The application provides a high-speed maglev tunnel clearance area aerodynamic determination method and system. 1、The application can accurately identify multiple most unfavorable working conditions controlled by different comfort indicators by limiting each value in the composite comfort standard and independently exploring and determining the critical tunnel length that maximizes the corresponding pressure change. This method overcomes the limitations of relying on a single or estimated most unfavorable working condition in traditional design, improves the accuracy and reliability of tunnel aerodynamic effect analysis, and ensures that the final design decision is based on comprehensive coverage of all potential risk points.

[0015] 2、The application realizes fine determination of the tunnel clearance area by iteratively solving the tunnel clearance area required to meet a single indicator under multiple identified most unfavorable working conditions and finally taking the maximum value as the design basis. This method ensures that the minimum tunnel clearance area determined can meet all comfort constraints and avoid unnecessary construction cost increases due to over-conservative estimates, thereby optimizing engineering economy under the premise of ensuring comfort.

[0016] 3、The application builds a complete design closed loop by closely coupling the vehicle time constant representing the sealing performance of the vehicle, the composite comfort standard defining the ride experience, and the tunnel geometric parameters. By systematically analyzing the pressure change of the most unfavorable car, the application can ensure that the final tunnel design scheme fully meets the pressure change indicators most sensitive to the human body, thereby providing more comprehensive and reliable comfort protection for passengers of high-speed maglev trains.

[0017] 4、The application establishes a mapping database between the composite comfort standard, the critical tunnel length, the vehicle time constant, and the minimum tunnel clearance area, and converts the complex aerodynamic calculation process into a systematic design basis. This not only greatly improves the efficiency of tunnel design, but also provides strong technical reserves and rapid decision support for future tunnel design under different lines, different vehicle types, or different comfort requirements, enhancing the flexibility and foresight of design. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The flowchart of the method of the application; Figure 2 The tunnel clearance area calculation program flowchart of the application; Figure 3 The high-speed maglev train external pressure time history curve example diagram of the application; Figure 4 The high-speed maglev train internal pressure time history curve example diagram of the application; Figure 5A schematic diagram of the influence of different carriages on the pressure comfort in the car of the present application; Figure 6 A schematic diagram of the maximum change of the pressure in the car of the present application over time with the change of the tunnel length; Figure 7 A schematic diagram of the maximum change of the pressure in the car of the present application over time with the change of the tunnel length; Figure 8 A schematic diagram of the maximum change of the pressure in the car of the present application over time with the change of the tunnel length; Figure 9 A schematic diagram of the maximum change of the pressure in the car of the present application over time with the change of the tunnel length; Figure 10 A schematic diagram of the maximum change of the pressure in the car of the present application over time with the change of the tunnel length; Figure 11 A schematic diagram of the tunnel clearance area distribution characteristics under the UIC standard of the present application; Figure 12 A schematic diagram of the tunnel clearance area distribution characteristics under the magnetic levitation standard of the present application.

[0019] Among them, 10, pressure acquisition module; 20, pressure calculation module; 30, working condition identification module; 40, area iteration module; 50, area determination module. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the specification of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0021] Referring to the drawings Figure 1 , Figure 1 It is the overall flow schematic diagram of the high-speed maglev transportation tunnel clearance area aerodynamic determination method according to an embodiment of the present application. The present application provides a high-speed maglev transportation tunnel clearance area aerodynamic determination method, which can include the following steps: S1, obtaining the external pressure time history curve of the high-speed maglev train when passing through the tunnel at a preset running speed; S2, based on the external pressure time history curve and the preset whole vehicle time constant, calculating and obtaining the internal pressure time history curve; S3, according to the multiple limit values contained in the preset composite comfort standard, calculating the multiple pressure change amounts corresponding to the internal pressure time history curve, and for each limit value, determining the critical tunnel length that makes the corresponding pressure change amount maximum; S4, in the working condition composed of each of the limit value and the critical tunnel length corresponding thereto, a single index tunnel clearance area required to meet the limit value is solved by iteratively adjusting the tunnel clearance area; S5, taking the maximum value in all the solved single index tunnel clearance areas as the minimum tunnel clearance area meeting the composite comfort standard.

[0022] The application also provides a high-speed maglev tunnel clearance area aerodynamic determination system, which is used to execute the above method. The system can include: A pressure acquisition module 10 is configured to acquire an external pressure time history curve of a high-speed maglev train passing through a tunnel at a preset running speed. A pressure calculation module 20 is configured to calculate an internal pressure time history curve based on the external pressure time history curve and a preset whole vehicle time constant. A working condition identification module 30 is configured to calculate a plurality of pressure change amounts corresponding to the internal pressure time history curve according to a plurality of limit values included in a preset composite comfort standard, and determine a critical tunnel length that makes the corresponding pressure change amount maximum for each of the limit values. An area iteration module 40 is configured to, in the working condition composed of each of the limit value and the critical tunnel length corresponding thereto, solve a single index tunnel clearance area required to meet the limit value by iteratively adjusting the tunnel clearance area. An area determination module 50 is configured to take the maximum value in all the solved single index tunnel clearance areas as the minimum tunnel clearance area meeting the composite comfort standard.

[0023] Referring to the accompanying Figure 1 , Figure 1 is a schematic diagram of the overall flow of the high-speed maglev tunnel clearance area aerodynamic determination method according to an embodiment of the application. The following will describe each step in the technical solution of the application in detail.

[0024] Step S1 is to acquire an external pressure time history curve of a high-speed maglev train passing through a tunnel at a preset running speed. The pressure time history curve is the basic input data for all subsequent comfort analysis. The curve can be acquired by two technical approaches: three-dimensional computational fluid dynamics simulation method or one-dimensional compressible unsteady non-equilibrium isentropic flow model.

[0025] When using the three-dimensional computational fluid dynamics simulation method, a precise three-dimensional geometric model of the train and the tunnel is established, and the Navier-Stokes equation set is solved under specified boundary conditions. This method can accurately simulate the complex flow field structure around the train when it enters and exits the tunnel, runs in the tunnel, and the propagation and superposition process of the pressure wave generated thereby. Since it can reflect the real flow details, the time history curve of the external pressure of the train calculated by this method is accurate, and it is suitable for design verification stage or fine analysis of specific working conditions.

[0026] When a large number of different parameters (such as a variety of tunnel lengths, clearance area combinations) need to be calculated and screened quickly, a one-dimensional compressible unsteady non-equilibrium flow model can be used. This model simplifies the unsteady flow in the tunnel into a one-dimensional problem along the axis of the tunnel, and solves the one-dimensional gas dynamics equation set by numerical methods such as the method of characteristics. This method is efficient and can quickly obtain the propagation and evolution of the pressure wave in the tunnel.

[0027] The one-dimensional flow model itself cannot take into account the local flow effects caused by the complex train shape. To improve the calculation accuracy of the one-dimensional model and make it reflect the influence of complex train shape and blockage ratio on pressure, this method introduces a pressure loss coefficient. This coefficient is calibrated for the one-dimensional model according to the specific parameters of the train, including the train shape (such as the streamline design of the head car and the tail car), the marshalling mode (such as the concave-convex structure at the car connection), and the blockage ratio of the train and the tunnel (i.e. the ratio of the maximum cross-sectional area of the train to the clearance area of the tunnel).

[0028] The pressure loss coefficient is used in the control equation of the one-dimensional compressible unsteady non-equilibrium flow model to equivalently represent the pressure loss in the annular space between the train head and tail, the train body surface, and the train and tunnel wall. These pressure losses are essentially caused by the aerodynamic phenomena caused by complex train shape and blockage ratio. The numerical value of the pressure loss coefficient can be pre-calibrated by referring to high-precision three-dimensional computational fluid dynamics simulation results or wind tunnel test data. By introducing this coefficient, the one-dimensional flow model can generate a more realistic physical process of the external pressure time history curve of the train while maintaining its high computational efficiency, especially in terms of the steepness of the pressure wave and the size of the peak value. The accuracy of the calculation results is significantly improved.

[0029] Referring to the accompanying Figure 1 and the accompanying Figure 4 After obtaining the external pressure time history curve of the train, step S2 is to calculate the internal pressure time history curve based on the curve. The change of the internal pressure is the result of the transmission of the external pressure wave through the gap existing in the train body structure to the inside of the car, and the change rate is directly related to the overall sealing performance of the train body.

[0030] In the present application, the overall sealing performance of a vehicle is quantitatively characterized by using the vehicle time constant, a physical quantity. The vehicle time constant is a comprehensive index, which reflects the time required for the pressure inside the vehicle to respond to the change of the pressure outside the vehicle when there is a pressure difference between the inside and outside of the vehicle. The larger the value of the constant is, the better the air tightness of the vehicle is, the slower the change of the pressure inside the vehicle is, and the stronger the attenuation effect of the pressure outside the vehicle is.

[0031] Based on the obtained pressure time history curve outside the vehicle and the preset vehicle time constant, the pressure inside the vehicle is calculated by using a lumped parameter model. The model regards the vehicle cabin as a cavity, and the calculation is recursively performed at each time step by using the following formula: In the formula, is the pressure inside the vehicle at the next time step, is the pressure inside the vehicle at the current time step, is the pressure value on the pressure time history curve outside the vehicle at the current time step, is a natural constant, is the vehicle time constant, is the time step. The formula describes that, in any small time step, the pressure inside the vehicle is composed of two parts: one part is the natural attenuation of the pressure inside the vehicle at the previous time step, and the other part is the result of the penetration of the pressure outside the vehicle at the current time step into the vehicle. By continuous iterative calculation, the complete pressure time history curve inside the vehicle can be obtained, as shown in FIG. 2. Figure 4

[0032] The vehicle time constant is a key input parameter, and its value needs to accurately reflect the actual sealing level of the train. One of the methods for determining the constant is to perform a static leak test. The test is performed in the stationary state of the train. First, the pressure inside the closed vehicle cabin is increased to a preset high pressure value (for example, 4 kPa relative to atmospheric pressure). Then, the pressure increase is stopped and the pressure measurement channel is opened, and the time required for the pressure inside the vehicle to naturally decrease from the preset high pressure value to a preset low pressure value (for example, 1 kPa relative to atmospheric pressure) is recorded. This time is defined as the static time constant of the specific train.

[0033] In actual operation, due to the airflow effect on the surface of the train body when the train is running at high speed, the dynamic air tightness performance is different from that in the static state. Therefore, the vehicle time constant used for calculating the pressure inside the vehicle (also referred to as the dynamic time constant) is usually obtained by modifying the static time constant. One method is to multiply the static time constant by a modification coefficient (for example, 1 / 2 to 1 / 3), or to determine the specific value according to a related technical standard or an experimentally verified empirical relationship. In this way, the pressure time history curve used for calculation can be ensured to be more consistent with the pressure change of the train under actual operating conditions.​​

[0034] Referring to the drawings Figure 5 to the drawings Figure 10 After obtaining the time history curve of the pressure in the vehicle, step S3 is to identify a plurality of most unfavorable working conditions which have a decisive influence on the design of the tunnel clearance area according to a preset composite comfort standard.

[0035] Firstly, the composite comfort standard on which the method is based is a set of indexes composed of a plurality of independent limit values, which are used to comprehensively evaluate the ear comfort of passengers. The standard usually includes limits on the pressure change amount in different time intervals, such as the maximum pressure change amount in 1 second ( ), the maximum pressure change amount in 3 seconds ( ), the maximum pressure change amount in 10 seconds ( ), etc., which mainly reflect the influence of the rate of pressure change on the human body. In addition, the standard also includes a limit on the extreme value of pressure change in any time ( ), which is used to control the total amplitude of pressure change. Each limit value corresponds to a dimension of comfort evaluation.

[0036] To ensure the rigor of the analysis, before identifying the working conditions, the most unfavorable car in the train formation needs to be determined. Due to the propagation and reflection characteristics of pressure waves in the train tunnel system, the pressure history experienced by cars at different positions in the train is different, resulting in differences in the internal pressure change amount. The steps to determine the most unfavorable car include: For all cars in the train, each according to its own time history curve of the pressure in the vehicle, the various pressure change amounts defined in the above composite comfort standard are calculated. Then, the same kind of pressure change amount of all cars is compared to find the car with the largest value. Referring to the drawings Figure 5 By comparison, the car whose pressure change reaches the maximum in multiple pressure change amount indexes can be determined as the most unfavorable car, and the subsequent analysis will be carried out for this car.

[0037] The core of this step is to identify a plurality of most unfavorable working conditions controlled by different comfort indexes. A most unfavorable working condition is defined by a pair of parameters: a comfort limit value, and a critical tunnel length at which the pressure change amount corresponding to the limit value reaches its theoretical maximum. Research shows that the maximum of different pressure change amount indexes does not occur at the same tunnel length.

[0038] Therefore, for each comfort limit value, the search for the critical tunnel length is carried out independently. The specific operation is: keeping the train parameters, running speed and initial tunnel clearance area unchanged, repeating steps S1 and S2 at a series of different tunnel lengths, and calculating the various pressure change amounts of the most unfavorable car under each tunnel length.

[0039] Referring to the attached Figure 6 to the attached Figure 10 , the regular curve of the pressure variation of each type with the tunnel length is drawn. By analyzing these curves, the critical tunnel length that makes each type of pressure variation reach its peak value can be determined. For example, from the attached Figure 7 and the attached Figure 8 , it can be observed that and have the same critical tunnel length (for example, 2 km), while from the attached Figure 9 , it can be observed that has a different critical tunnel length (for example, 10 km). Through this process, multiple most unfavorable working conditions (such as a 3-second pressure variation working condition under a 2-km tunnel length, a 60-second pressure variation working condition under a 10-km tunnel length, etc.) controlled by different comfort indicators (such as , , , etc.) are identified. This identification process lays the foundation for subsequent targeted iterative solving of the tunnel clearance area.

[0040] Referring to the attached Figure 2 , Figure 2 is a program flowchart of the iterative solving steps of the tunnel clearance area according to an embodiment of the present application. After identifying multiple most unfavorable working conditions composed of each comfort limit value and its corresponding critical tunnel length, step S4 is to determine the tunnel clearance area required to meet the single limit value under each of the working conditions through iterative solving.

[0041] This solving process is a reverse design process. For each identified most unfavorable working condition, the corresponding comfort limit value is the known convergence target, and the unknown quantity to be solved is the tunnel clearance area. The process is achieved through an iterative loop until the difference between the calculated pressure variation and the convergence target meets the preset convergence criterion.

[0042] Taking one of the most unfavorable working conditions as an example, the specific implementation of the iterative solving includes the following operations: First, set an initial tunnel clearance area for the first round of calculation. Take this tunnel clearance area, the critical tunnel length corresponding to the working condition, and other preset parameters as inputs, complete steps S1 and S2, calculate the in-vehicle pressure time history curve of the most unfavorable car, and extract the pressure variation corresponding to the working condition (for example, the maximum pressure variation within 3 seconds) from it.

[0043] Second, compare the calculated pressure variation with the comfort limit value corresponding to the working condition (i.e., the convergence target).

[0044] Then, the value of the tunnel clearance area is adjusted according to the comparison result for the next iteration. If the calculated pressure change is greater than the convergence target, it indicates that the current tunnel clearance area is too small, and the value of the tunnel clearance area should be increased in the next iteration. If the calculated pressure change is less than the convergence target, it indicates that the current tunnel clearance area is too large, and the value of the tunnel clearance area should be decreased in the next iteration. The adjustment amount of the tunnel clearance area can be determined according to a preset numerical algorithm (such as the bisection method or the Newton method).

[0045] This iteration loop continues, and in each iteration, it is necessary to judge whether the difference between the calculated pressure change and the convergence target meets the preset convergence criterion. The convergence criterion can be expressed as: ; In the formula, is the calculated pressure change in the current iteration round; is the comfort limit value corresponding to the working condition, i.e., the convergence target; is a preset positive number small enough, which is used as the convergence tolerance.

[0046] When the above convergence criterion is met, the iteration process is terminated. The tunnel clearance area used in the current iteration round is determined as the tunnel clearance area required to meet the single index (i.e., the single-index tunnel clearance area).

[0047] For all the most unfavorable working conditions identified in step S3, the above complete iteration solving process is repeated to obtain a set of single-index tunnel clearance areas that meet each comfort limit value.

[0048] After obtaining all the single-index tunnel clearance areas through step S4, step S5 is to determine a final design value from these solved area values, which is the minimum tunnel clearance area that can meet the composite comfort standard.

[0049] The principle of decision-making is that the finally designed tunnel clearance area must be able to meet each limit value in the composite comfort standard. Since different limit values and their corresponding most unfavorable working conditions have different requirements for the tunnel clearance area, one working condition may require a larger area to meet its constraint, while another working condition may have a relatively relaxed requirement for the area. In order to ensure that all constraint conditions can be met, the final tunnel clearance area selected must not be smaller than any of the single-index tunnel clearance areas. Therefore, to achieve the optimization of engineering economy on the premise of meeting all comfort requirements, the maximum value of all single-index tunnel clearance areas should be selected. The working condition corresponding to this maximum value is the controlling working condition in the entire design process.

[0050] Specifically, taking the set of all single-index tunnel clearance areas solved in step S4 as input, the minimum tunnel clearance area satisfying the composite comfort standard is determined by the following formula: ; In the formula, is the final determined minimum tunnel clearance area; is the set of all single-index tunnel clearance areas solved by step S4; is the single-index tunnel clearance area solved by iteration for the th limit value in the composite comfort standard at the critical tunnel length corresponding thereto; is the total number of limit values contained in the composite comfort standard.

[0051] The mathematical meaning of the formula is to take the maximum element in the set. After performing this operation, the obtained is the final result determined by the method of the present application, which can be directly used as a basis for tunnel engineering design.

[0052] To further illustrate the technical solutions provided by the present application, a specific example is described below.

[0053] This example aims to determine the minimum clearance area for the tunnel design of a specific high-speed maglev transportation system.

[0054] First, set the calculation parameters of this example. The train parameters are: 8-carriage formation, train total length of 205 meters, and train maximum cross-sectional area of 11.95 square meters. The running parameters are: the train running speed is set to 600 km / h. The initial tunnel parameters are: set an initial tunnel clearance area (e.g. 100 square meters) and a long enough tunnel length (e.g. 10 kilometers) for preliminary pressure waveform analysis.

[0055] This example will use two different composite comfort standards for comparative analysis. The first standard (standard A) is: the maximum pressure change within 1 second, 3 seconds, 10 seconds and 60 seconds is not more than 500 Pa, 800 Pa, 1000 Pa and 2000 Pa respectively. The second standard (standard B) is: the maximum pressure change within 1 second, 3 seconds and 10 seconds is not more than 300 Pa, 800 Pa and 1000 Pa respectively, and the pressure change extreme value within any time is not more than 1500 Pa.

[0056] At the same time, to study the influence of the vehicle sealing performance, this example selects multiple whole-vehicle time constants for calculation, for example, 83 seconds, 100 seconds and 125 seconds respectively.

[0057] Refer to the attachedFigure 3 Firstly, the initial parameters of the train, operation and tunnel are inputted into the one-dimensional compressible non-isentropic flow model to calculate the time-history curve of the external pressure at each compartment position. The pressure variation at one position is shown in Fig. 2. Figure 3

[0058] Referring to Fig. 3, the time-history curve of the internal pressure at each compartment is obtained by using the aforementioned internal pressure calculation formula based on the acquired time-history curve of the external pressure and the selected whole-train time constant (e.g. 83 seconds). Figure 4

[0059] Referring to Fig. 4, the various pressure variation quantities defined under the standards A and B are calculated for all the 8 compartments, respectively. The comparison of the maximum pressure at any time for different compartments under one working condition is shown in Fig. 5. It can be seen from the figure that the pressure variation quantity increases along the tail of the train running direction, and the pressure variation quantity of the 8th compartment (the tail car) is the largest. Therefore, the subsequent analysis takes the 8th compartment as the most unfavorable compartment. Figure 5 Figure 5

[0060] Referring to Fig. 6, the various pressure variation quantities defined under the standards A and B are calculated for all the 8 compartments, respectively. The comparison of the maximum pressure at any time for different compartments under one working condition is shown in Fig. 5. It can be seen from the figure that the pressure variation quantity increases along the tail of the train running direction, and the pressure variation quantity of the 8th compartment (the tail car) is the largest. Therefore, the subsequent analysis takes the 8th compartment as the most unfavorable compartment. Figure 6 Figure 10 To identify multiple most unfavorable working conditions, the tunnel length is systematically changed (e.g. from 0.5 km to 20 km) for the most unfavorable compartment, and the various pressure variation quantities defined under the standards A and B are calculated under different whole-train time constants. Figure 6 Figure 10 The variation law of the 1-second, 3-second, 10-second and 60-second maximum pressure variation quantities and the maximum pressure at any time with the tunnel length is shown in Figs. 6-9, respectively. It can be seen from the figures that the maximum value of different pressure variation quantity indicators appears at different tunnel lengths. For example, when the whole-train time constant is 83 seconds, the critical tunnel length of the 3-second and 10-second maximum pressure variation quantities is 2 km (as shown in Figs. 6 and 7), the critical tunnel length of the 60-second maximum pressure variation quantity is 10 km (as shown in Fig. 8), and the maximum pressure at any time continuously increases with the increase of the tunnel length (as shown in Fig. 9). Figure 7 Figure 8 Figure 9 Figure 10

[0061] After identifying the most unfavorable working conditions controlled by different comfort indicators, the iterative solution of the single-index tunnel clearance area is carried out for each working condition. Taking the standard B, the 3-second maximum pressure variation quantity and the 60-second maximum pressure variation quantity as the indicators, the tunnel clearance area is calculated for each working condition, and the results are shown in Figs. 10-12, respectively. ​​​​​​​​​​​​For example, in the specific scenario of =83 seconds and a tunnel length of 10 kilometers, the limiting values to be satisfied include no more than 300 Pa in 1 second, no more than 800 Pa in 3 seconds, no more than 1000 Pa in 10 seconds, and no more than 1500 Pa at any time. By iteratively solving with these four limiting values as convergence targets, respectively, four single-index tunnel clearance areas are obtained, for example, 56 m2, 70 m2, 85 m2, and 170 m2, respectively.

[0062] Finally, the maximum of these four single-index tunnel clearance areas, i.e., 170 m2, is taken as the minimum tunnel clearance area that satisfies the composite comfort standard in this scenario (standard B, =83 seconds, tunnel length 10 kilometers). Finally, the maximum of these four single-index tunnel clearance areas, i.e., 170 m2, is taken as the minimum tunnel clearance area that satisfies the composite comfort standard in this scenario (standard B, =83 seconds, tunnel length 10 kilometers).

[0063] By repeating the above complete process for all pre-set comfort standards, vehicle time constants, and tunnel lengths of interest, a database containing the mapping between comfort standards, critical tunnel lengths, vehicle time constants, and the determined minimum tunnel clearance areas can be established.

[0064] Referring to the attached Figure 11 and the attached Figure 12 , this database can be presented in graphical form. The attached Figure 11 shows the variation of the finally determined minimum tunnel clearance area with tunnel length and different vehicle time constants under standard A. The attached Figure 12 shows similar relationships under standard B. This database directly reveals the quantitative relationships between various design parameters, for example, under standard B, when the vehicle time constant is increased from 83 seconds to a higher value (e.g., 375 seconds or 450 seconds), the minimum tunnel clearance area required for a tunnel with a length of 15 kilometers can be significantly reduced from a higher value. This database provides direct technical support for engineers to make trade-offs between comfort, vehicle manufacturing cost (reflected in vehicle time constant), and tunnel construction cost (reflected in tunnel clearance area) when making design decisions.

[0065] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements, and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for determining the aerodynamic clearance of a high-speed maglev tunnel, characterized in that, The method comprises the following steps: S1, obtaining a time history curve of the external pressure of a high-speed maglev train passing through a tunnel at a preset running speed; S2, calculating a time history curve of the internal pressure based on the time history curve of the external pressure and a preset whole train time constant; S3, calculating a plurality of pressure change amounts corresponding to the time history curve of the internal pressure according to a plurality of limit values contained in a preset composite comfort standard, and determining a critical tunnel length that makes the corresponding pressure change amount reach a maximum value for each limit value; S4, adjusting the tunnel clearance area through iteration under the condition of each limit value and the corresponding critical tunnel length to solve the tunnel clearance area required for a single index that meets the limit value; S5, taking the maximum value of all the single-index tunnel clearance areas solved as the minimum tunnel clearance area that meets the composite comfort standard.

2. The method according to claim 1, wherein, In step S1, the step of obtaining the time history curve of the external pressure of the high-speed maglev train passing through the tunnel at the preset running speed comprises: A one-dimensional compressible unsteady non-equilibrium flow model or a three-dimensional computational fluid dynamics simulation method is used for calculation; When the one-dimensional compressible unsteady non-equilibrium flow model is used, different pressure loss coefficients can be introduced according to the train shape, marshalling mode and blockage ratio of the train and the tunnel to simulate the influence of complex train shape and blockage ratio on the external pressure.

3. The method according to claim 1, wherein, In step S2, the step of calculating the time history curve of the internal pressure based on the time history curve of the external pressure and the preset whole train time constant comprises: The time history curve of the external pressure and the whole train time constant are taken as inputs, and the following formula is used for step-by-step recursive calculation: ； wherein Pnext is the vehicle interior pressure at the next time instant, Pcurrent is the vehicle interior pressure at the current time instant, Pcurrent is the vehicle interior pressure at the current time instant, T is the vehicle time constant, dt is the time step.

4. The method according to claim 3, wherein, The vehicle time constant The determining step comprises: A static pressure relief test is performed on a specific train, and the time required for the internal pressure to drop from a preset high pressure value to a preset low pressure value is measured.

5. The method for determining the aerodynamic clearance of a high-speed maglev tunnel according to claim 1, wherein, Before step S3, it also includes: The pressure change amounts of all carriages of the train are compared to determine the most unfavorable carriage with the maximum pressure change amount, and for each limit value, a critical tunnel length that makes the corresponding pressure change amount of the most unfavorable carriage reach a maximum value is determined.

6. The method for determining the aerodynamic clearance of a high-speed maglev tunnel according to claim 1, wherein, In step S3, the step of calculating a plurality of pressure change amounts corresponding to the time history curve of the internal pressure according to a plurality of limit values contained in a preset composite comfort standard, and determining a critical tunnel length that makes the corresponding pressure change amount reach a maximum value for each limit value comprises: The composite comfort standard contains a plurality of different time intervals and a pressure change extreme value at any time; And for each limit value in the composite comfort standard, a critical tunnel length that makes the corresponding pressure change amount reach a maximum value is independently determined, so as to identify a plurality of most unfavorable working conditions controlled by different comfort indexes.

7. The method for determining the aerodynamic clearance of a high-speed maglev tunnel according to claim 1, wherein, In step S4, the step of adjusting the tunnel clearance area through iteration to solve the single-index tunnel clearance area required for the limit value comprises: The pressure variation obtained by calculation is compared with the convergence target in each iteration, and the value of the tunnel clearance area is adjusted according to the comparison result, until the difference between the pressure variation and the convergence target meets the preset convergence criterion, with the defined value as the convergence target.

8. The method for determining the aerodynamic clearance of a high-speed maglev tunnel according to claim 1, wherein, The step S5 includes: With the set of all solved single-index tunnel clearance areas as input, the minimum tunnel clearance area is determined by the following formula : ； wherein is the minimum tunnel clearance area, is the first is the single index tunnel clearance area required at the critical tunnel length corresponding to the first limiting value, is the total number of limiting values included in the composite comfort criterion.

9. The method for determining the aerodynamic clearance of a high-speed maglev tunnel according to claim 1, wherein, The method further includes: A mapping database is established between the composite comfort standard, the critical tunnel length, the whole vehicle time constant and the determined minimum tunnel clearance area.

10. A high-speed maglev transportation tunnel clearance area aerodynamic determination system, applied to the method of any one of claims 1-9, characterized in that, It includes: The pressure acquisition module is configured to acquire a time history curve of the external pressure of the high-speed maglev train when the high-speed maglev train passes through the tunnel at a preset running speed; The pressure calculation module is configured to calculate a time history curve of the internal pressure based on the time history curve of the external pressure and a preset whole vehicle time constant; The working condition recognition module is configured to calculate a plurality of pressure variations corresponding to the time history curve of the internal pressure according to a plurality of limit values included in the preset composite comfort standard, and determine a critical tunnel length that maximizes the corresponding pressure variation for each limit value; The area iteration module is configured to adjust the tunnel clearance area by iteration under a working condition formed by each limit value and the critical tunnel length corresponding thereto, and solve a single-index tunnel clearance area required to meet the limit value; The area determination module is configured to take the maximum value of all the single-index tunnel clearance areas solved as the minimum tunnel clearance area that meets the composite comfort standard.

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