Numerical Solution Method for the Safe Critical Wind Speed of Aerodynamic Braking of High-Speed Trains under Random Crosswind Loads

Abstract

The present invention relates to the fields of high-speed train aerodynamics and train wind resistance braking, and specifically relates to a numerical solution method for the safety critical wind speed of high-speed train wind resistance braking under the action of random crosswind loads. Starting from the safety braking control of a high-speed train equipped with a wind resistance braking device during the high-speed operation stage in a random crosswind environment, a high-speed train model equipped with a wind resistance braking device that meets different operating conditions and operating test conditions is constructed, a random wind model and a wind speed correction strategy are established. Through the multi-body dynamics simulation calculation of high-speed train wind resistance braking under the action of random crosswind loads, according to the maximum overturning coefficient of the vehicle, and considering the safety operation margin of random crosswinds, a theoretical evaluation and numerical solution method for the safety critical wind speed of wind resistance braking are scientifically given, which can provide strong reference and technical support for the development and application of the wind resistance braking systems of wheel-rail trains and high-speed maglev trains with a speed of 400+ km / h.

Description

Technical Field

[0001] The present invention relates to the fields of high-speed train aerodynamics and train wind resistance braking, and particularly relates to a numerical solution method for the safety critical wind speed of high-speed train wind resistance braking under the action of random crosswind loads. Background Art

[0002] In the research and development of the next-generation high-speed train technology with a speed of 400+ km / h, the development and utilization of aerodynamics have been widely concerned. As a non-adhesive supplementary braking method for high-speed trains during auxiliary braking or emergency braking at high speeds, wind resistance braking uses a wind resistance braking plate device arranged on the vehicle body surface to increase air resistance to generate braking force. It has the advantages of being clean and energy-saving, highly reliable, and having a large braking benefit in the high-speed section, and can effectively make up for the deficiency of adhesive braking force under high-speed driving conditions.

[0003] In recent years, domestic and foreign research and development and application of high-speed train wind resistance braking devices have carried out continuous exploratory theoretical research and on-line tests. Japan earliest carried out the application exploration of high-speed train wind resistance braking in the 1960s of the 20th century, and gradually carried out the aerodynamic calculation and mechanism optimization design of the wind resistance braking device for the MLU002N maglev train under the condition of a speed of 500 km / h. In June 2005, JR East Japan successfully assembled the "cat ear" type aerodynamic braking device on the E954 type Fastech360S and Fastech360Z high-speed trains, and at the same time completed the performance test of the wind resistance braking plate at a speed of 400 km / h. The results showed that the wind resistance braking device has high reliability and application value during emergency braking. After that, Japan explored aspects such as the opening method, driving method, structural strength, and effect of shortening the braking distance of the wind resistance braking device. At present, Japan still continues the research on wind resistance braking, and the ALFAGX Shinkansen train installed with the wind resistance braking device began trial operation in February 2020. In China, more research on the structural design and installation layout of wind resistance braking devices has been carried out in the past decade. The most classic at the present stage is the structural composition and conventional layout of the "butterfly" type wind resistance braking device. From the analysis of operation safety and stability, this device is currently a relatively preferred one. At the same time, many studies have also been carried out in numerical simulation and wind tunnel tests, but basically focused on the aerodynamic characteristics analysis of the wind resistance braking device, and there is little research on the vehicle-track dynamics characteristics of high-speed trains equipped with wind resistance braking devices under the action of wind loads.

[0004] The air resistance braking takes air as the main braking power source during the high-speed operation stage of high-speed trains, and effectively supplements the basic braking of high-speed trains. Its braking smoothness and safety are directly affected by the external wind environment. When a high-speed train equipped with an air resistance braking device is running, as the crosswind intensity increases, the crosswind effect becomes more prominent, the aerodynamic performance of the high-speed train deteriorates sharply, and the aerodynamic lateral force and lift both increase non-linearly. The aerodynamic load it receives seriously affects the dynamic performance of the train vehicle track, and may lead to train derailment, overturning and casualties. Random wind is one of the most uncertain factors affecting the running stability of high-speed trains and poses a serious threat to the running safety of high-speed trains. As an auxiliary braking in the high-speed stage, the air resistance braking device has an optimal applicable speed range above 350 km / h. The higher the running speed, the greater the effective braking force, and the more obvious the subsequent crosswind effect. At this time, the main measure to reduce this threat is to decelerate, and decelerating directly affects the braking efficiency of the air resistance braking device. Therefore, it is a necessary condition for the development and application of the air resistance braking device to evaluate the running safety and stability of high-speed trains equipped with the air resistance braking device under the action of random wind, propose a numerical solution method for the safety critical wind speed of the air resistance braking of high-speed trains under the action of random crosswind loads, and clarify the safety braking wind speed threshold in the random wind environment. Summary of the Invention

[0005] In order to evaluate the running safety and stability of high-speed trains equipped with air resistance braking devices under the action of random wind and clarify the safety braking wind speed threshold in the random wind environment, the present invention proposes a numerical solution method for the safety critical wind speed of the air resistance braking of high-speed trains under the action of random crosswind loads.

[0006] To achieve the above technical objectives, the present invention is implemented by adopting the following technical solutions:

[0007] A numerical solution method for the safety critical wind speed of the air resistance braking of high-speed trains under the action of random crosswind loads. The method starts from the safety braking control of the air resistance braking of high-speed trains equipped with air resistance braking devices during the high-speed operation stage in a random crosswind environment, constructs a high-speed train model equipped with air resistance braking devices that meets different operating conditions and operating test conditions, establishes a random wind model and a wind speed correction calculation method, and through the multi-body dynamics simulation calculation of the air resistance braking of high-speed trains under the action of random crosswind loads, determines the safety critical wind speed of the air resistance braking considering the safety crosswind margin according to the maximum overturning coefficient of the vehicle. The specific numerical solution method for the safety critical wind speed of the air resistance braking of high-speed trains under the action of random crosswind loads includes the following steps:

[0008] 1) Determination of the aerodynamic force coefficients of high-speed trains equipped with air resistance braking devices corresponding to different wind direction angles

[0009] 11) Geometric model

[0010] 111) Air resistance braking device model

[0011] The air resistance braking device adopts a plate structure that can meet the two-way braking operation. The longitudinal layout spacing between adjacent air resistance braking plates on the roof of the high-speed train is greater than or equal to 5m. The response time of a single-piece plate-type air resistance braking plate from opening to the stable braking working position is less than or equal to 0.5s. The normal working windward angle range of the single-piece plate-type air resistance braking plate is 75°, and it should meet the braking work evaluation requirements for any windward angle. The overall vehicle layout of the air resistance braking device adapts to the relevant technical requirements of the Chinese standard EMU train. The installation base of the air resistance braking device is required to achieve a smooth fit and transition after being installed with the streamlined outer shape of the train. One set of air resistance braking device is installed on the top of each vehicle. The air resistance braking device of the middle car is installed near the center position of the vehicle. The longitudinal installation position of the corresponding air resistance braking device of the middle car has an error of less than 2.5m on the premise of avoiding the roof air conditioner, pantograph, various antenna devices and ultra-high voltage cable devices. The air resistance braking devices of the head car and the tail car are respectively installed in the first 1 / 2 position section of the smooth section of the roof behind the corresponding driver's cab. When establishing the air resistance braking device model, structures with a full size less than 25mm can be ignored;

[0012] 112) Train model

[0013] The train model refers to the body streamlined characteristics and appearance of the Chinese standard EMU train, and adopts the actual formation length model. The train model requires horizontal symmetry processing. The outer contour characteristics of the body side, roof and bottom are required to be retained completely. Consider the bogie, pantograph, windshield, roof and bottom air conditioner equipment structure models, and conduct model simplification processing, ignoring the detailed structures such as windows and door handles; When establishing the train model, structures with a full size less than 25mm can be ignored;

[0014] 113) Line model

[0015] The calculation uses a long and open straight-line track, equipped with a full-size subgrade model and rail model that match the train model. The subgrade model adopts a long straight single-track ballastless track, and the track model adopts a standard gauge. The length of the track model is greater than or equal to the total longitudinal length of the calculation domain. The distance from the rail top to the bottom of the model is less than or equal to 1m. The bottom surface of the track model is at the same height as the bottom surface of the calculation domain. The embankment height of the subgrade model is 0. The error of the train model relative to the rail top is not more than 50mm;

[0016] 12) Calculation domain and boundary conditions

[0017] The minimum computational size of the computational domain is set as a hexahedron with length × width × height = (L + 24H) × 24H × 8H, where L is the full length of the high-speed train equipped with the wind resistance braking device for the test, and H is the characteristic height of the high-speed train equipped with the wind resistance braking device. The characteristic height is equal to the sum of the height of the test train and the maximum characteristic height of the wind resistance braking device; the upstream of the model in the length direction of the computational domain is greater than 8H, the downstream of the model in the length direction of the computational domain is greater than 16H, the upstream flow domain of the computational domain is greater than 8H, the downstream flow domain of the computational domain is greater than 16H. The two inlet boundary conditions of the computational domain are defined as velocity inlets, the two outlet boundary conditions of the computational domain are defined as pressure outlets, the surfaces of the car body and the wind resistance braking device are non-slip wall boundary conditions, the upper side of the computational domain is set as a non-slip smooth wall boundary condition, and the lower side (ground) of the external flow field is set as a moving wall boundary, and the magnitude and direction of the moving speed are the same as the incoming flow speed;

[0018] 13) Turbulence model and computational settings

[0019] In the numerical solution of the critical wind speed of the high-speed train equipped with the wind resistance braking device under the action of random crosswind loads, detached eddy simulation or large eddy simulation methods are used for turbulence simulation; when the wind resistance braking speed is greater than or equal to 300 km / h, the air is calculated according to the compressible model; the calculation parameters of environmental temperature, atmospheric pressure, and air density are set according to the actual working conditions of the wind resistance braking operation environment; the convergence criterion needs to satisfy that the order of magnitude of the normalized residuals of the flow field parameters is less than 10 -4 , and at the same time, the variation amplitude of the surface pressure on the windward side and the leeward side of the wind resistance braking plate is less than 2.5%;

[0020] 2) Random wind model and wind speed calculation

[0021] 21) Definition of random wind model data: According to the train speed v tr , average wind speed U mean , yaw angle β, and surface roughness length h z0 calculate the random wind speed; determine the reference height h z = 4 m;

[0022] The standard deviation σ u of the longitudinal instantaneous velocity component u of the random wind satisfies the following formula:

[0023]

[0024] In the formula: κ is the von Karman coefficient, and 0.4 is taken for the calculation; h z is the height from the ground; A is a constant related to the surface roughness length h z0 ;

[0025] The standard deviation σ v of the lateral instantaneous velocity component v of the random wind satisfies the following formula:

[0026]

[0027] Where: h BL is the boundary layer height;

[0028] The longitudinal turbulent integral scale x L u Satisfies the following equation:

[0029] x L u = Cz m

[0030] Where: C and m are coefficients, and their values depend on the surface roughness length h z0 ; z is the spatial position in the z direction of the model;

[0031] 22) Calculation of wind power spectral density

[0032] The dimensionless power spectral density of the pulsating wind speed component u of the relative moving point in the random wind model Is calculated and determined by the following equation:

[0033]

[0034] Where: Is the dimensionless wind speed frequency based on the longitudinal integral scale in the Cooper theory corresponding to the velocity component u; Is the dimensionless wind speed frequency based on the synthetic integral scale in the Cooper theory corresponding to the velocity component u; Is the dimensionless quantity of the synthetic turbulent integral scale of the velocity component u in the x y direction; c u Is the coefficient in the Cooper theory corresponding to the velocity component u;

[0035] The dimensionless power spectral density of the pulsating wind speed component v of the relative moving point in the random wind model Is calculated and determined by the following equation:

[0036]

[0037] Where, Is the dimensionless wind speed frequency based on the longitudinal integral scale in the Cooper theory corresponding to the velocity component v; Is the dimensionless wind speed frequency based on the synthetic integral scale in the Cooper theory corresponding to the velocity component v; Is the dimensionless quantity of the synthetic turbulent integral scale of the velocity component v in the x y direction; c v Is the coefficient in the Cooper theory corresponding to the velocity component v;

[0038] 23) Aerodynamic admittance function

[0039] Aerodynamic admittance function H of lift, drag and nodding moment of a high-speed train equipped with a wind resistance braking device 2 (f) = 1; Aerodynamic admittance function H of lateral force and rolling moment 2 (f) satisfies the following equation:

[0040]

[0041] In the formula: f is the wind speed frequency; L is the length of the train equipped with a wind resistance braking device; h is the height of the train equipped with a wind resistance braking device; γ uu (Δr, f) is the square root coherence function; y and z are the spatial positions of the model in the y and z directions respectively;

[0042] 3) Aerodynamic force calculation of a high-speed train equipped with a wind resistance braking device under random crosswind loads

[0043] Based on the aerodynamic admittance function described in step 2), according to the modified quasi-steady assumption, determine the lateral air volume U of the modified wind speed TC (t) and the longitudinal air volume v of the modified wind speed T (t), and calculate the aerodynamic force of a high-speed train equipped with a wind resistance braking device under random wind action; The calculation formula for the aerodynamic force of a high-speed train equipped with a wind resistance braking device under random crosswind loads is:

[0044]

[0045] In the formula: t is the time; ρ is the calculated air density; β is the yaw angle; C is the aerodynamic force coefficient; v rel-TC (t) is the modified relative wind speed; where in the above formula β(t) respectively satisfy the following equations:

[0046]

[0047] In the formula: v T is the wind speed component along the line direction relative to the moving point; U T is the wind speed component perpendicular to the line relative to the moving point;

[0048] 4) Creation of a multi-body dynamics model of a high-speed train equipped with a wind resistance braking device under random crosswind loads

[0049] The construction of the multi-body dynamics model of a high-speed train equipped with a wind resistance braking device should include the mass, moment of inertia during the opening process, and center of gravity position of the wind resistance braking device; At the same time, it should at least include the mass, moment of inertia, and center of gravity position of the car body, bogie, and wheelset; Consider the position of the suspension device and its vertical, lateral, and longitudinal stiffness, vertical and lateral damping;

[0050] 5) Determination of critical wind speed

[0051] 51) Calculate and obtain the time history curve of the wheel-rail vertical force under different working conditions;

[0052] 52) Calculate the overturning coefficient through the time history curve of the wheel-rail vertical force and perform a 2 Hz low-pass filter;

[0053] 53) Calculate and determine the most unfavorable bogie and the maximum overturning coefficient;

[0054] 54) Judgment of the maximum overturning coefficient of the most unfavorable bogie:

[0055] The safety index D of the maximum overturning coefficient corresponding to the most unfavorable bogie of the high-speed train equipped with the wind resistance braking device under the action of random crosswind load max is evaluated according to the following formula:

[0056]

[0057] In the formula: P0 is the average wheel-rail vertical force of the train without excitation; P i1 is the wheel-rail vertical force on the unloading side of the first wheel pair of the bogie; P j1 is the wheel-rail vertical force on the unloading side of the second wheel pair of the bogie;

[0058] 55) According to the maximum overturning coefficient D max inversely deduce and determine the critical wind speed v of the high-speed train equipped with the wind resistance braking device under the action of random crosswind load w_max ;

[0059] 6) Determination of the safety critical wind speed of the wind resistance braking

[0060] The safety critical wind speed v of the wind resistance braking of the high-speed train under the action of random crosswind load w_secu satisfies: v w_secu = v w_max -Δv, where Δv is the wind speed margin for side wind safety braking, and the value of Δv is calculated as not less than 5 m / s.

[0061] Preferably, the maximum characteristic height of the wind resistance braking device ranges from 0.25 to 0.50 m.

[0062] Preferably, in step 3), the lateral air volume U TC (t) of the corrected wind speed is calculated according to the following formula:

[0063]

[0064] In the formula: U TC is the corrected U T ; f n is the nth harmonic frequency; n is the general harmonic component of the wind speed spectrum; n max is UTC (t) The maximum harmonic order; ω0 is the fundamental frequency; φ n is the random phase;

[0065] The longitudinal air volume v of the corrected wind speed T (t) is calculated according to the following formula:

[0066]

[0067] In the formula: j n is the nth harmonic phase of v T (t); v T (f n ) is the nth harmonic amplitude obtained from the moving point turbulent power spectral density.

[0068] Preferably, the multi-body dynamics model further includes a non-linear system including wheel-rail contact geometry, wheel-rail creep, primary and secondary suspension systems, lateral buffers, and anti-hunting dampers; among which, the train dynamics parameters under the full-load state are used in the calculation, and the wheelset, bogie, and carbody are all regarded as rigid bodies, the elastic deformation of the rail is not considered, and the track irregularity excitation is not considered.

[0069] Preferably, when calculating the random phase φ n and the nth harmonic phase j of v T (t), the average value of multiple repetitions is taken, and the expanded uncertainty is 2 times the standard deviation. n The beneficial effects of the present invention are as follows: The numerical solution method for the wind resistance braking safety critical wind speed of a high-speed train under the action of a random crosswind load constructs a high-speed train model equipped with a wind resistance braking device under different operating conditions and operating test conditions in a random crosswind environment. Through the multi-body dynamics simulation calculation of the train, considering the random crosswind safety operation margin, a scientific theoretical evaluation method for the wind resistance braking safety critical wind speed is given, which can provide strong reference and technical support for the development and application of the wind resistance braking systems of wheel-rail trains with a speed of 400+ km / h and high-speed maglev trains.

[0070] Description of the Drawings Description of the Drawings

[0071] Figure 1 is the flow chart of the numerical solution method for the wind resistance braking safety critical wind speed of a high-speed train under the action of a random crosswind load according to the present invention;

[0072] Figure 2 is the schematic diagram of the relationship between the position of the calculation model and the load vector according to the present invention;

[0073] Figure 3 is the overall structure diagram of a typical wind resistance braking device adapted for testing according to the present invention;

[0074] Figure 4Layout diagram of the adapted air resistance braking device of the present invention on the roof of a standard formation high-speed train;

[0075] Figure 5 Multi-body dynamics model diagram of a high-speed train equipped with an air resistance braking device of the present invention. Specific embodiments

[0076] The present invention will be further described below with reference to the accompanying drawings:

[0077] As Figure 1 shown, a numerical solution method for the safe critical wind speed of the air resistance braking of a high-speed train under the action of a random crosswind load. The method starts from the safe braking control of the air resistance braking of a high-speed train equipped with an air resistance braking device during the high-speed operation stage in a random crosswind environment, constructs a high-speed train model equipped with an air resistance braking device that meets different operating conditions and operating test conditions, establishes a random wind model and a wind speed correction calculation method, and through the multi-body dynamics simulation calculation of the air resistance braking of a high-speed train under the action of a random crosswind load, determines the safe critical wind speed of the air resistance braking according to the maximum overturning coefficient of the vehicle, considering the safety crosswind margin; the specific numerical solution method for the safe critical wind speed of the air resistance braking of a high-speed train under the action of a random crosswind load includes the following steps:

[0078] 1) Determination of the aerodynamic coefficient of a high-speed train equipped with an air resistance braking device corresponding to different wind direction angles (reference for the spatial vector relationship between the coordinate system of the calculation model space position and the wind load action Figure 2 )

[0079] 11) Geometric model

[0080] 111) Air resistance braking device model (reference for the overall structure of a typical adapted air resistance braking device Figure 3 )

[0081] The air resistance braking device adopts a plate-type structure that can meet the two-way braking operation. The longitudinal layout spacing between adjacent air resistance braking plates on the roof of the high-speed train is greater than or equal to 5 m. The response time of a single-piece plate-type air resistance braking plate from opening to the stable braking working position is less than or equal to 0.5 s. The normal working windward angle range of the single-piece plate-type air resistance braking plate is 75°, and it should meet the braking work evaluation requirements for any windward angle; the overall vehicle layout of the air resistance braking device adapts to the relevant technical requirements of the Chinese standard EMU train, such as Figure 4As shown in the figure, the installation base of the air resistance braking device is required to achieve a smooth fit and transition after being installed with the streamlined shape of the train. One set of air resistance braking device is installed on the top of each vehicle. The air resistance braking device of the middle vehicle is installed near the center position of the vehicle. The longitudinal installation position of the corresponding air resistance braking device of the middle vehicle has an error of less than 2.5 m on the premise of avoiding the roof air conditioner, pantograph facilities, various antenna devices and UHV cable devices; the air resistance braking devices of the head vehicle and the tail vehicle are respectively installed in the first 1 / 2 position section of the smooth section of the roof behind the corresponding driver's cab; when establishing the air resistance braking device model, structures with a full size less than 25 mm can be ignored;

[0082] 112) Train model

[0083] The train model refers to the body streamlined characteristics and appearance shape of the Chinese standard EMU train, and adopts the actual formation length model. The train model is required to be processed for horizontal symmetry. The complete external contour characteristics are required to be retained on the side, roof and bottom of the car body. The structure models of bogies, pantographs, windshields, roof and bottom air conditioning equipment are considered, and model simplification is carried out. Details such as windows and door handles are ignored; when establishing the train model, structures with a full size less than 25 mm can be ignored.

[0084] 113) Line model

[0085] The calculation uses a long and open straight-line track, and is equipped with a full-size subgrade model and a rail model that match the train model. The subgrade model uses a long straight single-track ballastless track, and the track model uses a standard gauge. The length of the track model is greater than or equal to the total longitudinal length of the calculation domain. The distance from the rail top to the bottom of the model is less than or equal to 1 m. The bottom surface of the track model is at the same height as the bottom surface of the calculation domain. The embankment height of the subgrade model is 0. The error of the train model relative to the rail top is not more than 50 mm.

[0086] 12) Calculation domain and boundary conditions

[0087] The minimum computational size of the computational domain is set as a hexahedron with length × width × height = (L + 24H) × 24H × 8H, where L is the total length of the high-speed train equipped with the air resistance braking device for testing, and H is the characteristic height of the high-speed train equipped with the air resistance braking device. The characteristic height is equal to the sum of the height of the test train and the maximum characteristic height of the air resistance braking device; the upstream of the model in the length direction of the computational domain is greater than 8H, the downstream of the model in the length direction of the computational domain is greater than 16H, the upstream area of the windward side of the computational domain is greater than 8H, the downstream area of the leeward side of the computational domain is greater than 16H. The two inlet boundary conditions of the computational domain are defined as velocity inlets, the two outlet boundary conditions of the computational domain are defined as pressure outlets, the surfaces of the car body and the air resistance braking device are set as non-slip wall boundary conditions, the upper side of the computational domain is set as a non-slip smooth wall boundary condition, and the lower side (ground) of the external flow field is set as a moving wall boundary, and the magnitude and direction of the moving speed are the same as the oncoming flow velocity; the value range of the maximum characteristic height of the air resistance braking device is 0.25 - 0.50 m.

[0088] 13) Turbulence model and calculation settings

[0089] In the numerical solution of the critical wind speed of the high-speed train equipped with the air resistance braking device under the action of random crosswind loads, the turbulence simulation adopts the detached eddy simulation or large eddy simulation method; when the air resistance braking speed is greater than or equal to 300 km / h, the air is calculated according to the compressible model; the calculation parameters of environmental temperature, atmospheric pressure, and air density are set according to the actual working conditions of the air resistance braking operation environment; the convergence criterion needs to satisfy that the order of magnitude of the normalized residuals of the flow field parameters is less than 10 -4 , and at the same time, the change amplitude of the surface pressure on the windward side and the leeward side of the air resistance braking plate is less than 2.5%;

[0090] 2) Random wind model and wind speed calculation: including the definition of random wind model data, the calculation of wind power spectral density, and the determination of the aerodynamic admittance function.

[0091] 3) Aerodynamic force calculation of the high-speed train equipped with the air resistance braking device under the action of random crosswind loads

[0092] Based on the aerodynamic admittance function described in step 2), according to the modified quasi-steady hypothesis, the lateral air volume U TC (t) of the modified wind speed and the longitudinal air volume v T (t) of the modified wind speed are determined, and the aerodynamic force of the high-speed train equipped with the air resistance braking device under the action of random wind is calculated; the aerodynamic force calculation formula of the high-speed train equipped with the air resistance braking device under the action of random crosswind loads is:

[0093]

[0094] In the formula: t is time; ρ is the calculated air density; β is the yaw angle; C is the aerodynamic force coefficient; v rel-TC (t) is the modified relative wind speed; where in the above formula β(t) satisfies the following equations respectively:

[0095]

[0096] where: v T is the wind speed component in the line direction relative to the moving point; U T is the wind speed component perpendicular to the line relative to the moving point.

[0097] 4) Creation of the multi-body dynamics model of a high-speed train equipped with a wind resistance braking device under the action of random crosswind loads (refer to Figure 5 )

[0098] The construction of the multi-body dynamics model of a high-speed train equipped with a wind resistance braking device should include the mass of the wind resistance braking device, the moment of inertia during the opening process, and the position of the center of gravity; at the same time, it should include at least the mass, moment of inertia, and position of the center of gravity of the car body, bogie, and wheel set; consider the position of the suspension device and its vertical, lateral, and longitudinal stiffness, vertical and lateral damping.

[0099] The multi-body dynamics model also includes non-linear systems such as wheel-rail contact geometry, wheel-rail creep, primary and secondary suspension systems, lateral buffers, and anti-hunting dampers; among them, the dynamic parameters of the train under the full-load state are used in the calculation, and the wheel set, bogie frame, and car body are regarded as rigid bodies, without considering the elastic deformation of the rail and the track irregularity excitation.

[0100] 5) Determination of the critical wind speed

[0101] 51) Calculate and obtain the time history curve of the wheel-rail vertical force under different working conditions;

[0102] 52) Calculate the overturning coefficient through the time history curve of the wheel-rail vertical force and perform 2Hz low-pass filtering;

[0103] 53) Calculate and determine the most unfavorable bogie and the maximum overturning coefficient;

[0104] 54) Evaluation of the maximum overturning coefficient of the most unfavorable bogie:

[0105] The safety index D of the maximum overturning coefficient corresponding to the most unfavorable bogie of a high-speed train equipped with a wind resistance braking device under the action of random crosswind loads max is evaluated according to the following formula:

[0106]

[0107] where: P0 is the average wheel-rail vertical force of the train without excitation; P i1 is the wheel-rail vertical force on the unloading side of the first wheel pair of the bogie; P j1 is the wheel-rail vertical force on the unloading side of the second wheel pair of the bogie;

[0108] 55) According to the maximum overturning coefficient D max Back-calculate to determine the critical wind speed v of the high-speed train equipped with the aerodynamic braking device under the action of random crosswind load w_max .

[0109] 6) Determination of the safety critical wind speed of aerodynamic braking

[0110] The safety critical wind speed v of the aerodynamic braking of the high-speed train under the action of random crosswind load w_secu Satisfies: v w_secu = v w_max -Δv, where Δv is the wind speed margin for crosswind safety braking, and the value of Δv is calculated as not less than 5 m / s.

[0111] It should be noted that the "front", "rear", "upper", "lower" and other indications of orientation or positional relationship mentioned in this document are based on the positional relationship shown in the drawings, and are only for the convenience of describing the technical solution and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed or operated in a specific orientation. Therefore, it cannot be understood as a limitation to the technical solution. The connection relationship can refer to a direct connection relationship or an indirect connection relationship. The professional term symbols in this document are given corresponding marks and explanations in the order of appearance, and only explained once. The meanings, explanations or descriptions represented by the same marked symbols appearing subsequently are equally applicable.

[0112] Obviously, those skilled in the art can make various changes and deformations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and its equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. Numerical solution method for the safety critical wind speed of a high-speed train under random crosswind loads, characterized in that: Starting from the wind resistance braking safety braking control of a high-speed train equipped with a wind resistance braking device during the high-speed operation stage in a random crosswind environment, a high-speed train model equipped with a wind resistance braking device that meets different operating conditions and operating test conditions is constructed, a random wind model and a wind speed correction strategy are established, and through the multi-body dynamics simulation calculation of the wind resistance braking of a high-speed train under the action of a random crosswind load, the wind resistance braking safety critical wind speed is determined according to the maximum overturning coefficient of the vehicle, considering the safety crosswind margin. The specific numerical solution method for the wind resistance braking safety critical wind speed of a high-speed train under the action of a random crosswind load includes the following steps: 1) Determination of the aerodynamic coefficient of a high-speed train equipped with a wind resistance braking device corresponding to different wind direction angles: 11) Geometric model: 111) Wind resistance braking device model: The wind resistance braking device adopts a plate-type structure that can meet the two-way braking operation. The longitudinal layout spacing between adjacent wind resistance braking plates on the roof of the high-speed train is greater than or equal to 5m. The response time of a single-piece plate-type wind resistance braking plate from opening to the stable braking working position is less than or equal to 0.5s. The normal working windward angle range of the single-piece plate-type wind resistance braking plate is 75°, and it should meet the braking work evaluation requirements for any windward angle. The overall vehicle layout of the wind resistance braking device adapts to the relevant technical requirements of the Chinese standard EMU train. The installation base of the wind resistance braking device is required to achieve a smooth fit and transition after being installed with the streamlined outer shape of the train. One set of wind resistance braking device is installed on the top of each vehicle. The wind resistance braking device of the middle car is installed near the center position of the vehicle. The longitudinal installation position of the corresponding wind resistance braking device of the middle car has an error of less than 2.5m on the premise of avoiding the roof air conditioner, pantograph, various antenna devices, and ultra-high voltage cable devices. The wind resistance braking devices of the head car and the tail car are respectively installed in the first 1 / 2 position section of the smooth section of the roof behind the corresponding driver's cab. Structures with a full size less than 25mm can be ignored when establishing the wind resistance braking device model. 112) Train model: The train model refers to the body streamlined characteristics and appearance of the Chinese standard EMU train, and adopts the actual formation length model. The train model requires lateral symmetry processing. The side, roof, and bottom of the car body are required to retain the complete outer contour characteristics. Consider the bogie, pantograph, windshield, roof, and bottom air conditioner equipment structure models of the train, and perform model simplification processing, ignoring the detailed structures such as windows and door handles. Structures with a full size less than 25mm can be ignored when establishing the train model. 113) Line model: The calculation uses a long and open straight-line track, equipped with a full-size subgrade model and a rail model that match the train model. The subgrade model adopts a long straight single-track ballastless track, and the rail model adopts the standard gauge. The length of the rail model is greater than or equal to the total longitudinal length of the calculation domain. The distance from the rail top to the bottom of the model is less than or equal to 1m. The bottom surface of the rail model is at the same height as the bottom surface of the calculation domain. The embankment height of the subgrade model is 0. The error of the train model relative to the rail top is not greater than 50mm. 12) Calculation domain and boundary conditions: The minimum computational size of the computational domain is set as a hexahedron with length × width × height = (L + 24H) × 24H × 8H, where L is the total length of the high-speed train equipped with the wind resistance braking device during the test, and H is the characteristic height of the high-speed train equipped with the wind resistance braking device. The characteristic height is equal to the sum of the height of the test train and the maximum characteristic height of the wind resistance braking device; the upstream of the computational domain in the length direction of the model is greater than 8H, the downstream of the computational domain in the length direction of the model is greater than 16H, the upstream area of the computational domain facing the wind is greater than 8H, the downstream area of the computational domain on the leeward side is greater than 16H, the two inlet boundary conditions of the computational domain are defined as velocity inlets, the two outlet boundary conditions of the computational domain are defined as pressure outlets, the surfaces of the car body and the wind resistance braking device are non-slip wall boundary conditions, the upper side of the computational domain is set as a non-slip smooth wall boundary condition, and the lower side (ground) of the external flow field is set as a moving wall boundary, and the magnitude and direction of the moving speed are the same as the oncoming flow speed; 13) Turbulence model and computational settings: In the numerical solution of the critical wind speed of a high-speed train equipped with a wind resistance braking device under random crosswind loads, the turbulence simulation adopts the detached eddy simulation or large eddy simulation method; when the wind resistance braking speed is greater than or equal to 300 km / h, the air is calculated according to the compressible model; the calculation parameters of the environmental temperature, atmospheric pressure, and air density are set according to the actual working conditions of the wind resistance braking operation environment; the convergence criterion needs to satisfy that the order of magnitude of the normalized residuals of the flow field parameters is less than 10 -4 , and at the same time, the change amplitude of the surface pressure on the windward and leeward sides of the wind resistance braking plate is less than 2.5%; 2) Random wind model and wind speed calculation: 21) Definition of random wind model data: According to the train speed v tr , average wind speed U mean , yaw angle β, ground surface roughness length h z0 Calculate the random wind speed; Determine the reference height h z = 4m; Standard deviation σ of the longitudinal instantaneous velocity component u of random wind u Satisfies the following formula: where: κ is the von Karman coefficient, and 0.4 is taken for calculation; h z is the height from the ground; A is a constant related to the surface roughness length h z0 related; Standard deviation σ of the random wind's lateral instantaneous velocity component v v Satisfies the following formula: where: h BL is the boundary layer height; Longitudinal Turbulent Integral Scale x L u Satisfies the following equation: x L u = Cz m , where: C and m are coefficients, and their values depend on the surface roughness length h z0 ; z is the spatial position in the z direction of the model 22) Wind power spectral density calculation: Dimensionless power spectral density of the velocity component u of the pulsating wind speed at relatively moving points in the random wind model It is calculated and determined by the following formula: In the formula: is the dimensionless wind speed frequency based on the longitudinal integral scale in the Cooper theory corresponding to the velocity component u; is the dimensionless wind speed frequency based on the synthetic integral scale in the Cooper theory corresponding to the velocity component u; is the dimensionless quantity of the synthetic turbulent integral scale of the velocity component u in the xy direction; c u is the coefficient in the Cooper theory corresponding to the velocity component u; Nondimensional power spectral density of the pulsating wind speed component v of the relatively moving point in the random wind model It is calculated and determined by the following formula: In the formula, is the dimensionless wind speed frequency based on the longitudinal integral scale in the Cooper theory corresponding to the velocity component v; is the dimensionless wind speed frequency based on the composite integral scale in the Cooper theory corresponding to the velocity component v; is the dimensionless quantity of the composite turbulent integral scale of the velocity component v in the xy direction; c v is the coefficient in the Cooper theory corresponding to the velocity component v; 23) Aerodynamic admittance function: Aerodynamic admittance function \(H\) of lift, drag and nodding moment of a high-speed train equipped with a wind resistance braking device 2 (f) = 1; The aerodynamic admittance function \(H\) of lateral force and rolling moment 2 (f) satisfies the following formula: where: f is the wind speed frequency; L is the length of the train equipped with the wind resistance braking device; h is the height of the train equipped with the wind resistance braking device; γ uu (Δr,f) is the square root coherence function; y and z are the spatial positions of the model in the y and z directions respectively; 3) Aerodynamic force calculation of the high-speed train equipped with the wind resistance braking device under the action of random crosswind load: Based on the pneumatic admittance function described in step 2), according to the modified quasi-steady assumption, determine the lateral air volume U TC (t) of the modified wind speed and the longitudinal air volume v T (t) of the modified wind speed, and calculate the aerodynamic force of the high-speed train equipped with a wind resistance braking device under the action of random wind; the calculation formula for the aerodynamic force of the high-speed train equipped with a wind resistance braking device under the action of random crosswind load is: In the formula: t is time; ρ is the calculated air density; β is the sideslip angle; C is the aerodynamic coefficient; v rel-TC (t) is the corrected relative wind speed; among which in the above formula β(t) respectively satisfies the following formula: where: v T is the wind speed component in the line direction relative to the moving point; U T is the wind speed component perpendicular to the line relative to the moving point; 4) Creation of the multi-body dynamics model of the high-speed train equipped with the wind resistance braking device under the action of random crosswind load: The multi-body dynamics model of the high-speed train equipped with the wind resistance braking device should include the mass of the wind resistance braking device, the moment of inertia during the opening process, and the position of the center of gravity; at the same time, it should at least include the mass, moment of inertia, and position of the center of gravity of the car body, bogie, and wheelset; consider the position of the suspension device and its vertical, lateral, and longitudinal stiffness, vertical and lateral damping; 5) Determination of the critical wind speed: 51) Calculate and obtain the time history curve of the wheel-rail vertical force under different working conditions; 52) Calculate the overturning coefficient through the time history curve of the wheel-rail vertical force and perform a 2Hz low-pass filter; 53) Calculate and determine the most unfavorable bogie and the maximum overturning coefficient; 54) Evaluation of the maximum overturning coefficient of the most unfavorable bogie: The maximum overturning coefficient D corresponding to the most unfavorable bogie of a high-speed train equipped with a wind resistance braking device under random crosswind loads max The safety index is evaluated according to the following formula: Where: P0 is the average vertical wheel-rail force of the train without excitation; P i1 is the vertical wheel-rail force on the unloading side of the first wheel set of the bogie; P j1 is the vertical wheel-rail force on the unloading side of the second wheel set of the bogie; 55) According to the maximum overturning coefficient D max Back-calculate and determine the critical wind speed v of the high-speed train equipped with the aerodynamic braking device under the action of random crosswind loads w_max ; 6) Determination of the safety critical wind speed of the wind resistance braking: The safety critical wind speed v of the aerodynamic brake of a high-speed train under random crosswind loads w_secu satisfies: v w_secu = v w_max - Δv, where Δv is the wind speed margin for safety braking in crosswind, and the value of Δv is calculated as not less than 5 m / s.

2. The numerical solution method for the safety critical wind speed of the aerodynamic braking of a high-speed train under random crosswind loads according to claim 1, characterized in that: The value range of the maximum characteristic height of the wind resistance braking device is 0.25 - 0.50 m.

3. The numerical solution method for the safety critical wind speed of the aerodynamic braking of a high-speed train under random crosswind loads according to claim 1, characterized in that: In step 3), the crosswind volume U of the corrected wind speed TC (t) is calculated according to the following formula: Where: U TC is the corrected U T ; f n is the nth harmonic frequency; n is the general harmonic component of the wind speed spectrum; n max is the maximum harmonic order in U TC (t); ω0 is the fundamental frequency; φ n is the random phase; The longitudinal air volume v of the corrected wind speed T (t) is calculated according to the following formula: Where: j n is the nth harmonic phase of v T (t); v T (f n ) is the nth harmonic amplitude obtained from the moving point turbulent power spectral density.

4. The numerical solution method for the safety critical wind speed of the aerodynamic braking of a high-speed train under random crosswind loads according to claim 1, wherein: The multi-body dynamics model also includes non-linear systems such as wheel-rail contact geometry, wheel-rail creep, primary and secondary suspension systems, lateral buffers, and anti-hunting dampers; among them, the dynamic parameters of the train under the full-load state are used in the calculation, and the wheelset, bogie frame, and car body are all regarded as rigid bodies, the elastic deformation of the rail is not considered, and the track irregularity excitation is not considered.

5. The numerical solution method for the safety critical wind speed of the aerodynamic braking of a high-speed train under random crosswind loads according to claim 3, wherein: The random phase φ n and v T (t) of the nth harmonic phase j n When calculating, take the average value of repeated measurements multiple times, and the expanded uncertainty is 2 times the standard deviation.

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