A method and system for determining the aerodynamic clearance of a high-speed maglev tunnel

Abstract

The application relates to the technical field of high-speed rail transit tunnel aerodynamics design, and discloses a high-speed maglev transit tunnel clearance area aerodynamic determination method and system, which comprises the following steps: acquiring a time history curve of external pressure of a high-speed maglev train when the train passes through a tunnel at a preset running speed; calculating a time history curve of internal pressure based on the time history curve of external pressure and a whole train time constant; identifying a most unfavorable working condition which plays a decisive role in tunnel clearance area design according to a composite comfort standard; determining a tunnel clearance area required for meeting a single limited value by iterative solution under the most unfavorable working condition; and determining a final minimum tunnel clearance area from all 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. The application can realize economic and reasonable tunnel clearance area design which meets comfort requirements, and establishes a related mapping database to provide guidance for engineering design.

Description

Technical Field

[0001] This invention relates to the field of aerodynamic design technology for high-speed rail transit tunnels, specifically to a method and system for aerodynamically determining the clearance area of ​​a high-speed maglev transit tunnel. Background Technology

[0002] As a representative of the new generation of rail transit, the high-speed maglev train's ultra-high-speed operation causes aerodynamic effects when the train passes through tunnels that far exceed those of traditional wheel-rail trains. In particular, the rapid pressure fluctuations caused by the transmission of tunnel pressure waves into the carriage seriously affect the comfort of passengers' ears, causing physiological reactions such as ear fullness, ear pain, and even tinnitus, becoming a key factor restricting the riding experience.

[0003] Currently, the industry mainly addresses this issue through two approaches: first, increasing the tunnel clearance area to reduce the intensity of aerodynamic effects; and second, improving vehicle airtightness when tunnel clearance area is limited. However, both methods have limitations. Simply increasing the tunnel clearance area significantly improves comfort but also significantly increases tunnel construction costs, resulting in poor economic efficiency. While over-reliance on high vehicle airtightness can compensate for insufficient tunnel area to some extent, vehicle manufacturing processes are complex, and compromises still need to be made regarding tunnel clearance area. Existing technologies often lack a systematic consideration of the complex coupling relationship between vehicle airtightness, various comfort standards, and tunnel length when determining tunnel clearance area. Specifically, existing methods fail to provide an effective way to comprehensively balance and accurately match the relationship between these three factors, considering the differences in tunnel clearance area requirements for comfort indicators at different time scales (such as short-term pressure change rate and extreme values ​​of total pressure change), and the "most unfavorable" performance of aerodynamic effects at different tunnel lengths. Therefore, how to scientifically construct the optimal matching relationship between the airtightness and comfort standards of the vehicle body and the clearance area of ​​the tunnel, so as to achieve the economic rationality of the project construction while meeting the comfort of passengers, is a key technical problem that urgently needs to be solved in the field of high-speed maglev transportation.

[0004] Therefore, this invention proposes an aerodynamic method and system for determining the clearance area of ​​high-speed maglev transportation tunnels to address the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an aerodynamic method and system for determining the clearance area of ​​high-speed maglev transportation tunnels. This method solves the problem that when determining the clearance area of ​​high-speed maglev transportation tunnels, it is difficult to fully consider all potential worst-case conditions under composite comfort standards, which may lead to conservative design results or comfort risks.

[0006] To address the aforementioned technical problems, this invention provides a closed-loop determination method and system that couples vehicle body airtightness, composite comfort standards, and tunnel geometric parameters. This method can identify multiple most unfavorable operating conditions controlled by different comfort indices and iteratively solve for the minimum tunnel clearance area that satisfies all constraints.

[0007] The first aspect of this invention provides an aerodynamic method for determining the clearance area of ​​a high-speed maglev transportation tunnel, the method comprising: First, the time-history curves of the external pressure of the high-speed maglev train passing through the tunnel at a preset operating speed are obtained. This step can be calculated using a one-dimensional compressible unsteady non-entropic flow model or a three-dimensional computational fluid dynamics simulation method. When using a one-dimensional compressible unsteady non-entropic flow model, a corresponding pressure loss coefficient is introduced based on the specific shape of the train, its formation, and the blockage ratio between the train and the tunnel, to simulate the impact of complex train shapes and blockage ratios on the external pressure during the calculation.

[0008] Secondly, based on the obtained external pressure time history curve and the preset vehicle time constant, the internal pressure time history curve is calculated. This calculation step specifically involves using the external pressure time history curve and the vehicle time constant as inputs, and performing a step-by-step recursive calculation using the following formula: ; In the formula, For the next moment of vehicle interior pressure, The current pressure inside the car. This represents the pressure value on the time-history curve of the external pressure at the current moment. The time constant of the whole vehicle The time step is the vehicle time constant. This can be determined by conducting a static pressure relief test on a specific train, specifically by measuring the time required for the pressure inside the train to naturally decrease from a preset high pressure value to a preset low pressure value.

[0009] Next, based on a preset composite comfort standard, multiple most unfavorable operating conditions are identified. This composite comfort standard includes limits on pressure changes over multiple different time intervals and limits on the extreme values ​​of pressure changes over any given time period. This identification step first compares the pressure changes calculated from the in-car pressure time-history curves for all train carriages to determine the most unfavorable carriage with the largest pressure change. Then, for each limit value in the composite comfort standard, a critical tunnel length is independently determined that maximizes the pressure change corresponding to that limit value, thereby identifying multiple most unfavorable operating conditions controlled by different comfort indices.

[0010] Then, under the working condition consisting of each of the aforementioned limiting values ​​and the corresponding critical tunnel lengths, the tunnel clearance area is iteratively adjusted to solve for the single-index tunnel clearance area required to satisfy the limiting value. Specifically, this solution step involves: using the limiting value as the convergence target, comparing the calculated pressure change with the convergence target in each iteration, and adjusting the tunnel clearance area value for the next iteration based on the comparison result. This process is repeated until the difference between the calculated pressure change and the convergence target satisfies a preset convergence criterion.

[0011] Finally, the maximum value among all the calculated single-index tunnel clearance areas is taken as the minimum tunnel clearance area that satisfies the composite comfort standard. This step is specifically accomplished using the following formula: ; In the formula, To minimize the tunnel clearance area, For the first A single index representing the required tunnel clearance area at a given critical tunnel length. This represents the total number of limit values ​​included in the composite comfort standard.

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

[0013] A second aspect of the present invention provides an aerodynamic system for determining the clearance area of ​​a high-speed maglev transportation tunnel, the system comprising: The pressure acquisition module is used to acquire the time history curve of the external pressure of the high-speed maglev train when it passes through the tunnel at a preset operating speed; The pressure calculation module is used to calculate the in-vehicle pressure time history curve based on the external pressure time history curve and the preset vehicle time constant. The working condition identification module is used to calculate multiple pressure changes corresponding to the in-vehicle pressure time history curve based on multiple limiting values ​​included in the preset composite comfort standard, and for each limiting value, determine the critical tunnel length that makes the corresponding pressure change reach the maximum. The area iteration module is used to solve for the single index tunnel clearance area required to meet the limit value by iteratively adjusting the tunnel clearance area under the working condition consisting of each limit value and the corresponding critical tunnel length. The area determination module is used to take the maximum value among all the solved single-index tunnel clearance areas as the minimum tunnel clearance area that meets the composite comfort standard.

[0014] This invention provides an aerodynamic method and system for determining the clearance area of ​​a high-speed maglev transportation tunnel. It offers the following advantages: 1. This invention independently explores and determines the critical tunnel length that maximizes the corresponding pressure change for each limit value in a composite comfort standard. This invention can accurately identify multiple most unfavorable operating conditions controlled by different comfort indices. This method overcomes the limitations of traditional design methods that rely on a single or estimated most unfavorable operating condition, 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. This invention achieves refined determination of the tunnel clearance area by iteratively solving for the required tunnel clearance area to meet a single index under multiple identified most unfavorable working conditions, and finally taking the maximum value as the design basis. This method ensures that the final determined minimum tunnel clearance area not only meets all comfort constraints, but also avoids unnecessary increases in construction costs due to overly conservative estimates, thereby optimizing engineering economy while ensuring comfort.

[0016] 3. This invention constructs a complete design closed loop by tightly coupling the vehicle time constant, which represents the vehicle's sealing performance, the composite comfort standard defining the riding experience, and tunnel geometric parameters. By systematically analyzing the pressure changes in the most unfavorable carriage, this invention ensures that the final tunnel design fully meets the pressure change indicators most sensitive to the human body, thereby providing more comprehensive and reliable comfort guarantees for passengers of high-speed maglev trains.

[0017] 4. By establishing a mapping database between composite comfort standards, critical tunnel length, vehicle time constant, and minimum tunnel clearance area, this invention transforms 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 tunnel design under different routes, vehicle types, or comfort requirements in the future, enhancing the flexibility and foresight of the design. Attached Figure Description

[0018] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a flowchart of the tunnel clearance area calculation procedure of the present invention; Figure 3 This is an example diagram of the external pressure-time history curve of the high-speed maglev train according to the present invention; Figure 4 This is an example diagram of the pressure-time history curve inside the high-speed maglev train according to the present invention. Figure 5This is a schematic diagram illustrating the influence of different carriages on in-vehicle pressure comfort according to the present invention. Figure 6 This is a schematic diagram illustrating the variation of the maximum change in vehicle interior pressure over 1 second with tunnel length according to the present invention. Figure 7 This is a schematic diagram illustrating the variation of the maximum change in vehicle interior pressure over 3 seconds with tunnel length according to the present invention. Figure 8 This is a schematic diagram illustrating the variation of the maximum change in vehicle interior pressure over 10 seconds with tunnel length according to the present invention. Figure 9 This is a schematic diagram illustrating the variation of the maximum change in vehicle interior pressure over 60 seconds with tunnel length according to the present invention. Figure 10 This is a schematic diagram illustrating the variation of the maximum pressure inside the vehicle at any time with tunnel length according to the present invention. Figure 11 This is a schematic diagram illustrating the distribution characteristics of tunnel clearance area under the UIC standard of this invention; Figure 12 This is a schematic diagram illustrating the distribution characteristics of tunnel clearance area under the maglev standard of this invention.

[0019] Among them, 10 is the pressure acquisition module; 20 is the pressure calculation module; 30 is the working condition identification module; 40 is the area iteration module; and 50 is the area determination module. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] See attached document Figure 1 , Figure 1 This is a schematic flowchart illustrating the aerodynamic determination method for the clearance area of ​​a high-speed maglev transportation tunnel according to an embodiment of the present invention. The present invention provides an aerodynamic determination method for the clearance area of ​​a high-speed maglev transportation tunnel, which may include the following steps: S1. Obtain the time history curve of external pressure of a high-speed maglev train when it passes through a tunnel at a preset operating speed; S2. Based on the external pressure time history curve and the preset vehicle time constant, calculate the internal pressure time history curve. S3. Based on the multiple limiting values ​​included in the preset composite comfort standard, calculate the multiple pressure changes corresponding to the in-vehicle pressure time history curve, and for each of the limiting values, determine the critical tunnel length that makes the corresponding pressure change reach the maximum. S4. Under the working condition consisting of each of the aforementioned limiting values ​​and the corresponding critical tunnel length, the tunnel clearance area is iteratively adjusted to obtain the single index tunnel clearance area required to satisfy the limiting values. S5. Take the maximum value among all the solved single-index tunnel clearance areas as the minimum tunnel clearance area that satisfies the composite comfort standard.

[0022] This invention also provides an aerodynamic system for determining the clearance area of ​​a high-speed maglev transportation tunnel, which is used to perform the above-described method. The system may include: The pressure acquisition module 10 is used to acquire the time history curve of the external pressure of the high-speed maglev train when it passes through the tunnel at a preset operating speed. The pressure calculation module 20 is used to calculate the in-vehicle pressure time history curve based on the external pressure time history curve and the preset vehicle time constant. The working condition identification module 30 is used to calculate multiple pressure changes corresponding to the in-vehicle pressure time history curve based on multiple limiting values ​​included in the preset composite comfort standard, and for each limiting value, determine the critical tunnel length that makes the corresponding pressure change reach the maximum. The area iteration module 40 is used to solve for the single index tunnel net area required to satisfy the limit value by iteratively adjusting the tunnel net area under the working condition consisting of each limit value and the corresponding critical tunnel length. The area determination module 50 is used to take the maximum value among all the solved single index tunnel clearance areas as the minimum tunnel clearance area that meets the composite comfort standard.

[0023] See attached document Figure 1 , Figure 1 This is a schematic flowchart illustrating the aerodynamic determination method for the clearance area of ​​a high-speed maglev transportation tunnel according to an embodiment of the present invention. The various steps in the technical solution of the present invention will be described in detail below.

[0024] Step S1 involves obtaining the external pressure time history curve of the high-speed maglev train as it passes through a tunnel at a preset operating speed. This pressure time history curve serves as the foundational input data for all subsequent comfort analyses. This curve can be obtained through two technical approaches: three-dimensional computational fluid dynamics simulation or a one-dimensional compressible unsteady isentropic flow model.

[0025] When employing three-dimensional computational fluid dynamics simulation, an accurate three-dimensional geometric model incorporating the train and tunnel is established, and the Navier-Stokes equations are solved under specified boundary conditions. This method can accurately simulate the train entering and exiting the tunnel, the complex flow field structure surrounding it during operation within the tunnel, and the resulting pressure wave propagation and superposition process. Because it reflects realistic flow details, the calculated external pressure time history curves obtained by this method have high accuracy, making it suitable for design verification phases or for detailed analysis of specific operating conditions.

[0026] When rapid calculation and selection of a large number of different parameters (such as various combinations of tunnel lengths and clearance areas) are required, a one-dimensional compressible unsteady non-entropic flow model can be used. This model simplifies the unsteady flow within the tunnel into a one-dimensional problem along the tunnel axis, and solves the one-dimensional gas dynamics equations using numerical methods such as the characteristic line method. This method is computationally efficient and can quickly obtain the propagation and evolution of pressure waves within the tunnel.

[0027] One-dimensional flow models cannot account for the local flow effects caused by complex train shapes. To improve the computational accuracy of the one-dimensional model and enable it to reflect the impact of complex train shapes and congestion ratios on pressure, this method introduces a pressure loss coefficient. This coefficient is used to calibrate the one-dimensional model based on specific train parameters, including train shape (such as the streamlined design of the lead and tail cars), formation (such as the concave and convex structures at the car connections), and the congestion ratio between the train and the tunnel (i.e., the ratio of the train's maximum cross-sectional area to the tunnel's net area).

[0028] The pressure loss coefficient is used in the governing equations of the one-dimensional compressible unsteady isentropic flow model to equivalently represent the pressure loss at the front and rear of the train, the surface of the car body, and in the annular space between the train and the tunnel wall. These pressure losses are essentially caused by aerodynamic phenomena resulting from the complex train shape and blockage ratio. The 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 accurate external pressure time history curve that conforms to the actual physical process while maintaining its high computational efficiency, especially in terms of the steepness of the pressure wave waveform and the magnitude of the peak value, significantly improving the accuracy of the calculation results.

[0029] See attached document Figure 1 and attached Figure 4 After obtaining the external pressure time history curve, step S2 calculates the internal pressure time history curve based on this curve. The change in internal pressure is the result of external pressure waves being transmitted into the passenger compartment through gaps in the vehicle structure, and its rate of change is directly related to the overall sealing performance of the vehicle body.

[0030] In this invention, the overall sealing performance of a vehicle is quantified using the vehicle time constant. The vehicle time constant is a comprehensive indicator that reflects the time required for the pressure inside the vehicle to respond to changes in the external pressure when a pressure difference exists between the inside and outside of the vehicle. A larger value indicates better airtightness, slower pressure changes inside the vehicle, and a stronger attenuation effect on external pressure fluctuations.

[0031] Based on the acquired external pressure time history curve and the preset vehicle time constant, the internal pressure is calculated using a lumped parameter model. This model treats the vehicle compartment as a cavity and performs hourly recursive calculations using the following formula: ; In the formula, For the next moment of vehicle interior pressure, The current pressure inside the car. This represents the pressure value on the time-history curve of the external pressure at the current moment. It is a natural constant. The time constant of the whole vehicle Let be the time step. This formula describes the cabin pressure within any tiny time step, consisting of two parts: one part is the natural decay of the cabin pressure from the previous moment, and the other part is the result of the infiltration of external pressure into the cabin at the current moment. Through continuous iterative calculations, the complete cabin pressure time history curve can be obtained, as shown in the attached figure. Figure 4 As shown.

[0032] The overall vehicle time constant is a key input parameter, and its value needs to accurately reflect the actual sealing level of the train. One method to determine this constant is to conduct a static pressure relief test. This test is conducted with the train stationary. First, the sealed carriage is pressurized until the internal pressure reaches a preset high pressure value (e.g., 4 kPa relative to atmospheric pressure). Then, pressurization is stopped and the pressure relief measurement channel is opened. The time required for the internal pressure to naturally decrease from the preset high pressure value to a preset low pressure value (e.g., 1 kPa relative to atmospheric pressure) is recorded. This time is defined as the static time constant of that specific train.

[0033] In actual operation, due to the airflow effect on the train body surface during high-speed travel, its dynamic airtightness differs from that in static operation. Therefore, the whole-vehicle time constant (also known as the dynamic time constant) used in calculating in-vehicle pressure is usually obtained by correcting the static time constant. One established method is to multiply the static time constant by a correction factor (e.g., taking 1 / 2 to 1 / 3), or to determine its specific value based on relevant technical standards or empirically verified relationships. In this way, it can be ensured that the in-vehicle pressure time history curve used for calculation more closely reflects the pressure changes of the train under actual operating conditions.

[0034] See attached document Figure 5 To be continued Figure 10 After obtaining the time-history curve of the in-vehicle pressure, step S3 is to identify several of the most unfavorable working conditions that play a decisive role in the design of the tunnel clearance area based on the preset composite comfort standard.

[0035] First, the composite comfort standard upon which this method is based is a set of indicators consisting of multiple independent limit values, used to comprehensively evaluate passenger auditory comfort. This standard typically includes limits on the amount of pressure change inside the vehicle over different time intervals, such as the maximum pressure change within one second (…). ), Maximum pressure change within 3 seconds ( ), Maximum pressure change within 10 seconds ( These indicators primarily reflect the impact of the rate of pressure change on the human body. Furthermore, the standard also includes limits on the extreme values ​​of pressure change over any given time period. This is used to control the overall magnitude of pressure changes. Each limit value corresponds to a dimension of comfort evaluation.

[0036] To ensure the rigor of the analysis, the most unfavorable car in the train formation needs to be identified before performing operational condition identification. Due to the propagation and reflection characteristics of pressure waves in the train tunnel system, the pressure history experienced by cars at different locations on the train varies, resulting in differences in the amount of pressure change within them. The steps to determine the most unfavorable car include: For all train carriages, the pressure variations defined in the aforementioned composite comfort standard were calculated based on their respective in-car pressure time-history curves. Subsequently, the same pressure variation was compared across all carriages, and the carriage with the largest value was identified. (See Appendix) Figure 5 By comparison, it can be determined that the car with the largest pressure change under multiple pressure change indicators is the most unfavorable car, and subsequent analysis will be conducted on this car.

[0037] The core of this step lies in identifying multiple worst-case scenarios controlled by different comfort indices. A worst-case scenario is defined by a pair of parameters: a comfort limit and the critical tunnel length at which the pressure change corresponding to that limit reaches its theoretical maximum. Studies have shown that the maximum values ​​of different pressure change indices do not occur at the same tunnel length.

[0038] Therefore, this method independently searches for the critical tunnel length for each comfort constraint. Specifically, while keeping train parameters, operating speed, and initial tunnel clearance constant, steps S1 and S2 are repeated for a series of different tunnel lengths to calculate the pressure changes of the most unfavorable carriage at each tunnel length.

[0039] See attached document Figure 6 To be continued Figure 10 The curves showing the variation of each pressure change with tunnel length were plotted. By analyzing these curves, the critical tunnel length at which each pressure change reaches its peak can be determined. For example, from the attached... Figure 7 and attached Figure 8 It can be observed that, and The critical tunnel length is the same (e.g., 2km), while from the attached Figure 9 It was observed that, The critical tunnel length is a different value (e.g., 10 km). Through this process, it is possible to identify tunnels with different comfort indices (…). , , The system controlled multiple most unfavorable operating conditions (such as a 3-second pressure change condition under a 2km tunnel length, a 60-second pressure change condition under a 10km tunnel length, etc.). This identification process laid the foundation for subsequent targeted iterative solutions for the tunnel clearance area.

[0040] See attached document Figure 2 , Figure 2 This is a flowchart illustrating the iterative solution steps for tunnel clearance area according to an embodiment of the present invention. After identifying multiple most unfavorable operating conditions consisting of each comfort constraint and its corresponding critical tunnel length, step S4 determines the tunnel clearance area required to satisfy a single constraint under each operating condition through iterative solution.

[0041] This solution process is a reverse engineering process. For each identified worst-case scenario, the corresponding comfort constraint is a known convergence target, while the unknown quantity to be solved is the tunnel clearance area. This process is implemented through an iterative loop until the difference between the calculated pressure change and the convergence target satisfies a preset convergence criterion.

[0042] Taking one of the most unfavorable working conditions as an example, the specific implementation of this iterative solution includes the following operations: First, an initial tunnel clearance area is set for the first round of calculations. Using this tunnel clearance area, the critical tunnel length corresponding to this working condition, and other preset parameters as inputs, steps S1 and S2 are executed completely to calculate the time history curve of the in-car pressure in the most unfavorable carriage, and the pressure change corresponding to this working condition (e.g., the maximum pressure change within 3 seconds) is extracted from it.

[0043] Next, the calculated pressure change is compared with the comfort limit (i.e., convergence target) corresponding to the operating condition.

[0044] Then, based on the comparison results, the value of the tunnel clearance area is adjusted 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 its value needs to 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 its value needs to 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 Newton's method).

[0045] This iterative cycle continues. In each iteration, it is necessary to determine whether the difference between the calculated pressure change and the convergence target satisfies the preset convergence criterion. This convergence criterion can be expressed as: ; In the formula, This represents the pressure change calculated in the current iteration. This is the comfort limit value corresponding to this working condition, i.e., the convergence target; Let a pre-defined, sufficiently small positive number serve as the convergence tolerance.

[0046] The iteration process terminates when the above convergence criterion is met. The tunnel clearance area used in the current iteration round is determined as the tunnel clearance area required to meet this single indicator (i.e., the single indicator tunnel clearance area).

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

[0048] After obtaining the tunnel clearance area of ​​all individual indicators through step S4, step S5 determines a final design value from these solved area values, which serves as the minimum tunnel clearance area that can meet the composite comfort standard.

[0049] The principle behind this decision is that the final designed tunnel clearance area must simultaneously meet every constraint value in the composite comfort standard. Since different constraints and their corresponding worst-case scenarios place different demands on the tunnel clearance area, one scenario may require a larger area to meet its constraints, while another may have a relatively lenient area requirement. To ensure that all constraints are met, the selected final tunnel clearance area must not be less than any of the individual single-criteria tunnel clearance areas. Therefore, to optimize engineering economy while meeting all comfort requirements, the maximum value among all single-criteria tunnel clearance areas should be selected. The scenario corresponding to this maximum value is the controlling scenario in the entire design process.

[0050] Specifically, using the set of all single-index tunnel clearance areas solved in step S4 as input, the minimum tunnel clearance area that satisfies the composite comfort standard is determined by the following formula: ; In the formula, The final determined minimum tunnel clearance area; It is a set consisting of all the single-index tunnel clearance areas obtained in step S4; It is the first in the composite comfort standard A single index, the tunnel clearance area, is obtained by iterative solution under a given critical tunnel length and a specified limit. It is the total number of limit values ​​included in the composite comfort standard.

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

[0052] To further illustrate the technical solution provided by the present invention, a specific embodiment will be described below.

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

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

[0055] This embodiment 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 does not exceed 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 does not exceed 300 Pa, 800 Pa, and 1000 Pa, respectively, and the extreme pressure change within any time period does not exceed 1500 Pa.

[0056] Meanwhile, to study the impact on vehicle body sealing performance, this embodiment selected multiple vehicle time constants for calculation, for example, Take 83 seconds, 100 seconds, and 125 seconds respectively.

[0057] See attached document Figure 3 First, using a one-dimensional compressible non-entropic flow model, and inputting the initial parameters for the train, its operation, and the tunnel, the time-history curves of the external pressure at each carriage location are calculated. (Appendix) Figure 3 The pressure changes at one of the locations are shown.

[0058] See attached document Figure 4 Based on the obtained external pressure time history curve and the selected vehicle time constant (e.g., =83 seconds), using the aforementioned formula for calculating the pressure inside the car, the time history curve of the pressure inside the car of each carriage of the train is obtained by recursively calculating step by step.

[0059] See attached document Figure 5 To determine the most unfavorable car, various pressure variations defined under Standard A and Standard B were calculated for all eight cars. (Appendix) Figure 5 The figure shows a comparison of the maximum pressure values ​​at any time for different carriages under a given operating condition. As can be seen from the figure, the pressure changes inside the carriages increase towards the rear of the train along the direction of travel, with the 8th carriage (the last car) exhibiting the largest pressure changes in all aspects. Therefore, subsequent analyses will consider the 8th carriage as the most unfavorable carriage.

[0060] See attached document Figure 6 To be continued Figure 10 To identify multiple worst-case operating conditions, the tunnel length was systematically varied (e.g., from 0.5 km to 20 km) for the most unfavorable carriage, and the pressure changes defined by Standard A and Standard B were calculated under different vehicle time constants. (Appendix) Figure 6 To be continued Figure 10 The graphs show the maximum pressure change over 1 second, 3 seconds, 10 seconds, and 60 seconds, as well as the maximum pressure at any given time, as a function of tunnel length. As can be seen from the graphs, the maximum values ​​for different pressure change indices occur at different tunnel lengths. For example, in… At 83 seconds, the critical tunnel length for the maximum pressure change over 3 seconds and 10 seconds is 2 kilometers (see attached). Figure 7 and attached Figure 8 As shown in the attached diagram), the critical tunnel length for the maximum pressure change in 60 seconds is 10 kilometers. Figure 9 As shown in the figure), the maximum pressure at any given time continuously increases with the increase of tunnel length (as shown in the attached figure). Figure 10 (As shown).

[0061] After identifying the most unfavorable working conditions controlled by different comfort indices, an iterative solution for the tunnel clearance area using a single index is performed for each working condition. (Based on Standard B...) Taking a specific scenario of 83 seconds and a tunnel length of 10 kilometers as an example. In this scenario, the constraints to be met include no more than 300 Pa within 1 second, no more than 800 Pa within 3 seconds, no more than 1000 Pa within 10 seconds, and no more than 1500 Pa at any given time. By iteratively solving for these four constraints as convergence objectives, four single-indicator tunnel clearance areas can be obtained, for example, 56 square meters, 70 square meters, 85 square meters, and 170 square meters.

[0062] Finally, the maximum value among these four single indicators of tunnel clearance area, namely 170 square meters, is taken as the standard for this scenario (Standard B). =83 seconds, tunnel length 10 kilometers) minimum tunnel clearance area that meets composite comfort standards.

[0063] By repeating the entire process described above for all preset comfort standards, vehicle time constants, and tunnel lengths of interest, a database containing the mapping relationship between comfort standards, critical tunnel lengths, vehicle time constants, and the determined minimum tunnel clearance area can be established.

[0064] See attached document Figure 11 and attached Figure 12 This database can be presented in chart format. (Attached) Figure 11 This demonstrates the relationship between the final determined minimum tunnel clearance area and tunnel length and different vehicle time constants under Standard A. (Appendix) Figure 12 This demonstrates a similar relationship under Standard B. The database visually reveals the quantitative relationships between various design parameters. For example, under Standard B, when the vehicle time constant increases from 83 seconds to a higher value (such as 375 seconds or 450 seconds), the minimum required tunnel clearance area for a 15-kilometer-long tunnel can be significantly reduced from a higher value. This database provides engineers with direct technical support for making design decisions, allowing them to weigh comfort, vehicle manufacturing costs (reflected in the vehicle time constant), and tunnel construction costs (reflected in the tunnel clearance area).

[0065] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for aerodynamically determining the clearance area of ​​a high-speed maglev transportation tunnel, characterized in that, Includes the following steps: S1. Obtain the time history curve of the external pressure of the high-speed maglev train when it passes through the tunnel at a preset operating speed; wherein, a one-dimensional compressible unsteady non-entropic flow model is used for calculation, and the pressure loss coefficient is determined according to the train shape, formation and the blocking ratio between the train and the tunnel. The pressure loss coefficient is pre-calibrated by referring to the high-precision three-dimensional computational fluid dynamics simulation results or wind tunnel test data, and the pressure loss coefficient is introduced into the control equation of the one-dimensional compressible unsteady non-entropic flow model to equivalently represent the pressure loss at the front and rear of the train, the surface of the car body and the annular space between the train and the tunnel wall. S2. Based on the external pressure time history curve and the preset vehicle time constant, calculate the internal pressure time history curve of each carriage of the train. For all carriages of the train, calculate each pressure change amount defined in the preset composite comfort standard according to their respective internal pressure time history curves. Compare the same pressure change amount of all carriages, find the carriage with the largest value, and determine the carriage with the largest pressure change under multiple pressure change indicators as the most unfavorable carriage. Use the most unfavorable carriage as the analysis object for determining the critical tunnel length in step S3. S3. Based on the multiple limiting values ​​included in the preset composite comfort standard, calculate the multiple pressure changes corresponding to the time history curve of the in-vehicle pressure of the most unfavorable compartment. The composite comfort standard includes limits on pressure changes over multiple different time intervals and limits on extreme pressure changes over any time interval. For each limit value in the composite comfort standard, a critical tunnel length is independently determined to maximize the corresponding pressure change, thereby identifying multiple most unfavorable operating conditions controlled by different comfort indices. Each of the most unfavorable operating conditions consists of a limit value and a critical tunnel length that maximizes the pressure change corresponding to that limit value. S4. Under each of the most unfavorable working conditions, the tunnel clearance area is adjusted iteratively to solve for the single index tunnel clearance area required to meet the corresponding limit value. Using the limiting value corresponding to the most unfavorable working condition as the convergence target, in each iteration, the calculated pressure change is compared with the convergence target; if the calculated pressure change is greater than the convergence target, the tunnel clearance area is increased in the next iteration; if the calculated pressure change is less than the convergence target, the tunnel clearance area is decreased in the next iteration, until the difference between the pressure change and the convergence target satisfies the preset convergence criterion; S5. Take the maximum value among all the solved single-index tunnel clearance areas as the minimum tunnel clearance area that satisfies the composite comfort standard; using the set of all solved single-index tunnel clearance areas as input, determine the minimum tunnel clearance area using the following formula. : ； In the formula, To minimize the tunnel clearance area, For the first A single index representing the required tunnel clearance area at a given critical tunnel length. This represents the total number of limit values ​​included in the composite comfort standard.

2. The aerodynamic method for determining the clearance area of ​​a high-speed maglev transportation tunnel according to claim 1, characterized in that, Step S2, the step of calculating the in-vehicle pressure time history curve based on the external pressure time history curve and the preset vehicle time constant, includes: Using the external pressure time history curve and the vehicle time constant as input, the following formula is used for hourly recursive calculation: ； In the formula, For the next moment of vehicle interior pressure, The current pressure inside the car. This represents the pressure value on the time-history curve of the external pressure at the current moment. The time constant of the whole vehicle For time step.

3. The aerodynamic method for determining the clearance area of ​​a high-speed maglev transportation tunnel according to claim 2, characterized in that, The vehicle time constant The determination steps include: A static pressure relief test was conducted 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 was measured.

4. The aerodynamic method for determining the clearance area of ​​a high-speed maglev transportation tunnel according to claim 1, characterized in that, The method further includes: Establish a mapping database between the composite comfort standard, the critical tunnel length, the vehicle time constant, and the determined minimum tunnel clearance area.

5. A system for determining the aerodynamic clearance area of ​​a high-speed maglev transportation tunnel, applied to the method described in any one of claims 1-4, characterized in that, include: The pressure acquisition module is used to acquire the time history curve of the external pressure of the high-speed maglev train when it passes through the tunnel at a preset operating speed; The pressure calculation module is used to calculate the in-vehicle pressure time history curve based on the external pressure time history curve and the preset vehicle time constant. The working condition identification module is used to calculate multiple pressure changes corresponding to the in-vehicle pressure time history curve based on multiple limiting values ​​included in the preset composite comfort standard, and for each limiting value, determine the critical tunnel length that makes the corresponding pressure change reach the maximum. The area iteration module is used to solve for the single index tunnel clearance area required to meet the limit value by iteratively adjusting the tunnel clearance area under the working condition consisting of each limit value and the corresponding critical tunnel length. The area determination module is used to take the maximum value among all the solved single-index tunnel clearance areas as the minimum tunnel clearance area that meets the composite comfort standard.

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