Wind resistance braking operation safety assessment method for high-speed train in gust environment

Abstract

The invention relates to the field of high-speed train aerodynamics and train wind resistance braking, in particular to a high-speed train wind resistance braking operation safety assessment method in a gust environment. The wind resistance braking operation safety and derailment boundary of a high-speed train assembled with a wind resistance braking device in a strong gust environment are taken as targets, and a double-index dynamic gust model is established according to a gust space-time distribution state on the basis of testing an aerodynamic load coefficient of the high-speed train under the action of multi-working-condition stable wind; a high-speed vehicle and rail coupling dynamic derailment model considering the gust effect is established, and through high-speed train wind resistance braking multi-body dynamics simulation calculation, under the condition that all derailment judgment criterion limit value indexes and safety margin of high-speed train wind resistance braking operation are comprehensively considered, the high-speed train wind resistance braking multi-body dynamic derailment model is established on the basis of a wind tunnel test and a numerical simulation mode. The wind resistance braking operation safety evaluation method for the high-speed train in the gust environment is scientifically provided, and the method has important practical significance for determining the derailment and operation safety domain of the wind resistance braking vehicle of the high-speed train in the gust environment.

Description

Technical Field

[0001] The invention relates to the fields of high-speed train aerodynamics and train windage braking, and in particular to a method for evaluating the operation safety of high-speed train windage braking in a gust environment. Background Art

[0002] In the technical research and development of the next generation of high-speed trains with a speed of 400+km / h, the development and utilization of aerodynamics has always received extensive attention. Wind resistance braking is a non-adhesion supplementary braking method for high-speed trains during auxiliary braking or emergency braking at high speeds. It uses wind resistance brake plates on the surface of the vehicle body to increase air resistance to generate braking force. It has the advantages of being clean and energy-saving, highly reliable, and having large braking benefits in high-speed sections. It can effectively make up for the lack of adhesion braking force under high-speed driving conditions.

[0003] In recent years, both at home and abroad, continuous theoretical research and online tests have been carried out on the development and application of wind resistance brakes for high-speed trains. Japan first explored the application of wind resistance brakes for high-speed trains in the 1960s, and gradually carried out aerodynamic calculations and mechanism optimization designs of wind resistance brakes for MLU002N maglev trains at a speed of 500 km / h. In June 2005, JR East successfully installed "cat ear" aerodynamic brakes on E954 Fastech360S and Fastech360Z high-speed trains, and completed the performance test of wind resistance brake plates running at 400 km / h. The results showed that the wind resistance brake has high reliability and application value in emergency braking. Since then, Japan has explored the opening method, driving method, structural strength and effect of shortening the braking distance of wind resistance brakes. At present, Japan is still continuing its research on wind resistance brakes, and the ALFAGX Shinkansen train equipped with wind resistance brakes began trial operation in February 2020. In the past 10 years, China has also conducted a lot of research on the structural design and installation layout of wind resistance brakes. At present, the most classic is the structural composition and conventional layout of the "butterfly-type" wind resistance brake. From the perspective of operational safety and stability, this device is currently the preferred one. At the same time, many studies have been carried out in numerical simulation and wind tunnel testing, but they are basically focused on the analysis of the aerodynamic characteristics of wind resistance brakes. There is little research on the track dynamics characteristics of high-speed train vehicles equipped with wind resistance brakes under gust loads.

[0004] Wind resistance braking uses air as the main braking power source during the high-speed operation of high-speed trains, and effectively supplements the basic braking of high-speed trains. Its braking stability and safety are directly affected by the external wind environment. When a high-speed train equipped with a wind 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 increase nonlinearly. Strong gusts are one of the natural disasters that threaten the safety of high-speed train operation. In recent years, strong gusts have caused many major train derailment accidents. With the rapid expansion of the global high-speed railway network, the probability of high-speed trains encountering strong gusts during operation is increasing, especially when passing through coastal and desert windy areas. Once encountering strong gusts, the aerodynamic performance of high-speed trains deteriorates rapidly, and the prominent crosswind effect may cause train derailment, overturning and casualties, and the losses caused are immeasurable.

[0005] At present, with the increase of the speed of the new generation of high-speed trains and the popularization of lightweight design technology of the car body, the aerodynamic lateral force acting on the train body in the gust environment will be greatly increased, and the stability brought by the train's own mass will be rapidly reduced, further enhancing the sensitivity of the train operation safety to the crosswind and overturning risk. Therefore, the present invention studies the typical "hat-shaped" gust model that may be encountered during the operation of the high-speed train, establishes a dynamic derailment model of train and track coupling under the action of gusts, and comprehensively analyzes the dynamic response, derailment mechanism, and key influencing factors of high-speed vehicles under strong gusts by solving the corresponding critical wind speed curves of multiple operating conditions, and gives a speed 400km / h high-speed train operation safety speed threshold considering multiple key influencing factors and derailment evaluation criteria, proposes a high-speed train wind resistance braking operation safety assessment method in a gust environment, and determines the derailment and operation safety domain of high-speed train wind resistance braking vehicles in a gust environment, which is one of the technical problems to be solved in the development and application of wind resistance braking devices. Summary of the invention

[0006] In order to evaluate the operation safety and stability of high-speed trains equipped with wind resistance brakes in gusty environments and determine the derailment and operation safety domain of high-speed train wind resistance brakes in gusty environments, the present invention proposes an operation safety evaluation method for high-speed train wind resistance brakes in gusty environments.

[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0008] A method for evaluating the operation safety of wind resistance braking of high-speed trains in a gusty environment is provided. The method takes the wind resistance braking operation safety and derailment boundary of a high-speed train equipped with a wind resistance braking device in a strong gust environment as the target. Based on the wind tunnel test aerodynamic load coefficient under the action of multiple working conditions of a high-speed train under steady wind, a double exponential dynamic gust model is created according to the spatiotemporal distribution state of the gust, and a dynamic derailment model of a high-speed vehicle and track coupling under the action of gusts is established. Through multi-body dynamics simulation calculation of wind resistance braking of high-speed trains under the action of gust loads, various derailment evaluation criteria indicators of high-speed trains are comprehensively compared and calculated. Under the condition of considering the safety margin, the derailment and operation safety domain of the wind resistance braking vehicle of the high-speed train in a gust environment is determined. The method for evaluating the operation safety of wind resistance braking of high-speed trains in a specific gust environment includes the following steps:

[0009] 1) Determination of aerodynamic loads on high-speed trains equipped with windage brakes

[0010] 11) Test model: The test model of the high-speed train equipped with a wind resistance brake device adopts a standard vehicle model consisting of a lead car with the worst running stability in a windy environment and a half-section auxiliary car body, and the lead car is equipped with a set of wind resistance brake devices; the wind resistance brake device is installed in the front 1 / 2 position section of the roof smooth section behind the driver's cab of the lead car; when establishing the wind resistance brake device model, structures with a full size less than 25mm can be ignored; the standard ground configuration model is a single-line ballastless track;

[0011] 12) Determination method: The aerodynamic load of a high-speed train equipped with a wind resistance brake can be determined by wind tunnel test or computer numerical simulation;

[0012] 13) Test determination content: Based on the standard vehicle model and the standard ground configuration model described in step 11), the aerodynamic load coefficients of the wind resistance brake device corresponding to the working posture under the action of uniform wind at different slip angles of 0° to 90° are calculated respectively, including the longitudinal force coefficient, lateral force coefficient, lift coefficient, rolling moment coefficient, nodding moment coefficient, and sideslip moment coefficient, and the sideslip angle-coefficient table is completed. The calculation origin of the aerodynamic load coefficient is located at the center of the longitudinal direction of the two bogies and the intersection of the track centerline and the track surface; the calculated gradient of the slip angle is not greater than 5°, and the general form of the slip angle-coefficient table is as follows:

[0013] Side slip angle Longitudinal force coefficient Lateral force coefficient Lift coefficient Rolling moment coefficient Nodding torque coefficient Cornering moment coefficient 0° 5° 10° … 85° 90°

[0014] 2) Dynamic gust model establishment

[0015] The hat-shaped gust model is used in the calculation to approximate the dynamic wind field. The hat-shaped gust model is described by spatial distribution. When the train running speed is constant, the spatial distribution can also be equivalently converted into time distribution. The time and space distribution calculation of the hat-shaped gust model includes solving the time constant and the longitudinal and transverse wind speeds relative to the line.

[0016] The time constant T is calculated by the power spectral density of the longitudinal component, and the formula is as follows:

[0017]

[0018] Where: is the average time constant; S u (n) is the power spectrum density; n is the frequency range of the calculated or measured data, and n is calculated as [1 / 3000Hz, 1Hz]; v mean is the average wind speed, and v is calculated mean =v max G, where G is the gust factor, G = 1.4016; σ u is the standard deviation of wind speed; f u is the dimensionless frequency; is the turbulence integral scale, and the statistical value measured at a ground height of 4 m is used for calculation;

[0019] Longitudinal wind speed u relative to the line x , lateral wind speed u y Calculated by time constant and wind direction angle, the formula is as follows:

[0020]

[0021] Where: β is the distance from the wind load action point to the maximum gust amplitude; w is the wind direction angle;

[0022] The correlation of gusts is expressed by a coherence function, which satisfies the following exponential decay curve:

[0023]

[0024] Where: Coh represents the coherence function; C ux , C uy All are coefficients, and C is used for calculation. ux =5, C uy =16;

[0025] According to the dynamic gust wind speed v w The gust wind speed v is calculated by adding the steady wind speed and the fluctuating wind speed w , the formula is as follows:

[0026] v w =v mean +2.5σ u Coh

[0027] The minimum wind speed of the dynamic gust model can only approach the average wind speed v infinitely. mean , when calculating wind speed and vmean When the error between is less than 1%, it can be considered that the exponential decay reaches the lower limit, and the complete distribution of the dynamic gust model can be obtained by symmetric processing about the longitudinal y axis;

[0028] 3) Establishment of vehicle-track coupling model

[0029] In the vehicle model, the car body, bogie and wheelset can be regarded as rigid bodies, and their longitudinal, lateral, sinking and floating, rolling, nodding and shaking degrees of freedom are considered respectively, and a multi-rigid body vehicle system model with multiple degrees of freedom is established; the car body and the bogie are connected by a secondary suspension, and the wheelset and the bogie are connected by a primary suspension, and the nonlinear characteristics of the secondary lateral shock absorber, anti-snaking shock absorber and lateral stopper are fully considered; the car body and the wind resistance brake device are integrated and embedded in the lateral center position of the roof of the car body. The vehicle layout of the wind resistance brake device is adapted to the relevant technical requirements of the Chinese standard EMU train. The installation base of the wind resistance brake device is required to achieve a smooth fit transition with the streamlined shape of the train after installation; the wheel-rail creep is nonlinear, and the solution of the wheel-rail normal force adopts the Hertz nonlinear elastic contact theory, and the wheel-rail creep force is calculated according to the Kalker linear theory and nonlinear correction is made; the influence of track unevenness excitation on the safety of train wind resistance braking operation under gusts is not considered;

[0030] 4) Gust aerodynamic load loading and calculation

[0031] 41) Gust aerodynamic load loading: When calculating, the wind load is simplified into a concentrated force system acting on the vehicle body, which at least includes longitudinal force, lateral force, lift, rolling moment, nodding moment, and yaw moment. The action point of the concentrated force system is located at the center of the longitudinal direction of the two bogies and the intersection of the track centerline and the track surface, which is consistent with the calculation origin of the aerodynamic load coefficient in step 13);

[0032] 42) Calculation of gust aerodynamic loads: The aerodynamic force and aerodynamic moment are calculated as follows:

[0033]

[0034] At the same time, the vector relationship between the synthetic wind speed slip angle, wind speed, vehicle speed and wind direction angle satisfies the following formula:

[0035]

[0036] Where: v t is the train running speed; w is the wind direction angle; ρ is the air density; v a is the resultant velocity; β(t) is the slip angle, which is related to time t; are respectively the aerodynamic force and moment coefficient, which are related to the sideslip angle β(t); S is the characteristic cross-sectional area of ​​the train; d is the characteristic length of the train; the characteristic cross-sectional area of ​​the train and the characteristic length of the train are calculated by taking the unified standard value according to the test model;

[0037] 5) Derailment and operation safety domain determination of high-speed train wind resistance braking vehicles under gusts

[0038] 51) Selection of safety evaluation criteria for wind resistance braking of high-speed trains: The safety evaluation criteria for wind resistance braking of high-speed trains under gusts should at least include the wheel-rail vertical force P, wheel-rail lateral force Q, wheel-axle lateral force H, derailment coefficient Q / P, wheel load reduction rate ΔP / P, overturning coefficient D, and vehicle body lateral displacement Y. c 、Rolling angle displacement of vehicle body φ c ;

[0039] 52) Determination of the most dangerous derailment wheelset under gusts: According to the motion posture of each wheelset of the train under the action of wind load, determine the wheelset of the vehicle that will derail first corresponding to each evaluation criterion during the gust loading time;

[0040] 53) Determination of high-speed train derailment and safety area: Based on the most dangerous derailment wheel determined in step 52), according to the high-speed train windage braking operation safety evaluation criteria proposed in step 51), the high-speed train windage braking derailment and safety area under the combined effect of three key factors: vehicle speed, wind speed, and wind direction angle are comprehensively calculated, and the train windage braking operation safety critical surface and derailment critical surface containing vehicle speed, wind speed, and wind direction angle are drawn to determine the windage braking operation safety area, warning area, and derailment area;

[0041] 6) Verification of the evaluation method: Compare the derailment and safety areas in the gusty environment with the test train in the non-wind resistance braking operation state to determine whether there is an area where the wind resistance braking operation exceeds the limit range. If so, return to recalculate and determine.

[0042] Preferably, the spatiotemporal distribution of the dynamic gust model can be divided into 6 stages, namely: t0<t<t1 is a windless state, t1<t<t2 is a linear rising state, t2<t<t3 is an average wind speed state, t3<t<t5 is an exponential rise and decay state, t5<t<t6 is an average wind speed state, and t6<t<t7 is a linear decay state. The calculation formula is as follows:

[0043]

[0044] Where: v w (t) is the dynamic gust wind speed function; t0, t1, t2 t7 are time points.

[0045] As a preferred embodiment, the index limit values ​​corresponding to the wind resistance braking operation safety judgment criteria respectively meet the following requirements: wheel-rail vertical force P≤170kN; wheel-rail lateral force Q≤0.4(P st1 +P st2 ), P st1 ,P st2 are the static loads of the left and right wheels respectively, and P is taken as st1 +P st2 The train axle weight is 17t; the wheel axle lateral force H≤(10+P0 / 3), P0 is the static axle weight; the derailment coefficient Q / P≤0.8; the wheel load reduction rate ΔP / P≤0.8; the overturning coefficient D=(P2-P1) / (P2+P1)≤0.8, P1 and P2 are the wheel-rail pressures on the inner and outer rail sides of the vehicle respectively; the vehicle body lateral displacement Y c and the vehicle body roll angle displacement φ c The corresponding safety index limits are determined by testing the vehicle technical standards.

[0046] The beneficial effects of the present invention are as follows: the method aims at the wind resistance braking operation safety and derailment boundary of a high-speed train equipped with a wind resistance braking device in a strong gust environment, based on testing the aerodynamic load coefficient of the high-speed train under the action of multi-operating conditions of stable wind, creating a double-exponential dynamic gust model according to the spatiotemporal distribution state of the gust, establishing a dynamic derailment model of the high-speed vehicle and track coupling under the action of the gust, through the multi-body dynamics simulation calculation of the wind resistance braking of the high-speed train under the action of the gust load, and taking into account the limit value index and safety margin of each derailment evaluation criterion of the wind resistance braking operation of the high-speed train, a scientific method for evaluating the operation safety of the wind resistance braking of the high-speed train in a gust environment is given based on two methods of wind tunnel test and numerical simulation, which has important practical significance for determining the derailment and operation safety domain of the wind resistance braking vehicle of the high-speed train in the gust environment, and can provide a strong technical guarantee for the development and application of the wind resistance braking system of the wheel-rail train with a speed of 400km / h+ and the high-speed maglev train. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a flow chart of the method for safety assessment of wind resistance braking operation of high-speed trains in a gust environment of the present invention;

[0048] Figure 2 A wind tunnel test and numerical simulation calculation model and ground configuration for determining aerodynamic loads of a high-speed train equipped with a wind resistance brake device of the present invention;

[0049] Figure 3 It is a schematic diagram of the time-space distribution of the hat-shaped gust model of the present invention;

[0050] Figure 4 A schematic diagram of the relationship between aerodynamic load loading and vector for a high-speed train equipped with a windage brake device according to the present invention;

[0051] Figure 5 A diagram of a high-speed train vehicle-track coupling model equipped with a windage braking device according to the present invention;

[0052] Figure 6 This is the overall structure diagram of a typical windage brake device for the adaptation test of the present invention;

[0053] Figure 7 The layout diagram of the wind resistance brake device of the present invention on the roof of a standard marshaling high-speed train;

[0054] Figure 8 The present invention is a diagram illustrating an example of a curve of the vehicle wind resistance braking operation safety limit index changing with gust loading time (v t =200km / h,β w =90°,v max =15m / s);

[0055] Fig. 9 The present invention is a diagram illustrating an example of a curve of the vehicle wind resistance braking operation safety limit index changing with vehicle speed (β w =90°);

[0056] Fig.10 The present invention is used to calculate the corresponding vehicle wind resistance braking derailment / safety area in a hat-shaped gust environment using the method described in the present invention. DETAILED DESCRIPTION

[0057] The present invention will be further described below in conjunction with the accompanying drawings:

[0058] like Figure 1 As shown in the figure, the wind resistance braking operation safety assessment method for high-speed trains in gusty environments takes the wind resistance braking operation safety and derailment boundary of high-speed trains equipped with wind resistance braking devices in strong gust environments as the target, based on the wind tunnel test aerodynamic load coefficient of high-speed trains under multi-condition stable wind, a double exponential dynamic gust model is created according to the spatiotemporal distribution of gusts, and a dynamic derailment model of high-speed vehicles and tracks coupled with gusts is established. Through multi-body dynamics simulation calculation of wind resistance braking of high-speed trains under gust loads, comprehensive comparison and calculation of various derailment evaluation criteria indicators of high-speed trains are performed, and the derailment and operation safety domain of wind resistance braking vehicles of high-speed trains in gusty environments is determined while considering the safety margin; the wind resistance braking operation safety assessment method for high-speed trains in specific gust environments includes the following steps:

[0059] 1) Determination of aerodynamic loads on high-speed trains equipped with wind resistance brakes (Wind tunnel test and numerical simulation calculation model and ground configuration reference for determination of aerodynamic loads on high-speed trains equipped with wind resistance brakes) Figure 2 )

[0060] 11) Test model: The test model of the high-speed train equipped with a wind resistance brake device adopts a standard vehicle model consisting of a lead car with the worst running stability in a windy environment and a half-section auxiliary car body. The lead car is equipped with a set of wind resistance brake devices. The overall structure of a typical wind resistance brake device is referenced Figure 6 ; The wind resistance brake device is installed in the front 1 / 2 position section of the roof smooth section behind the driver's cab of the lead vehicle; when establishing the wind resistance brake device model, the structure with a full size less than 25mm can be ignored; the standard ground configuration model is a single-line ballastless track;

[0061] 12) Determination method: The aerodynamic load of a high-speed train equipped with a wind resistance brake can be determined by wind tunnel test or computer numerical simulation;

[0062] 13) Test determination content: Based on the standard vehicle model and the standard ground configuration model described in step 11), the aerodynamic load coefficients of the wind resistance brake device corresponding to the working posture under the action of uniform wind at different slip angles of 0° to 90° are calculated respectively, including the longitudinal force coefficient, lateral force coefficient, lift coefficient, rolling moment coefficient, nodding moment coefficient, and sideslip moment coefficient, and the sideslip angle-coefficient table is completed. The calculated slope of the slip angle is not greater than 5°; the calculation origin of the aerodynamic load coefficient is located at the center of the longitudinal direction of the two bogies and the intersection of the track centerline and the track surface (the relationship between the calculation model space position coordinate system and the space vector under the action of wind load is referenced). Figure 4 ).

[0063] 2) Dynamic gust model establishment

[0064] The hat-shaped gust model is used in the calculation to approximate the dynamic wind field. The hat-shaped gust model is described by spatial distribution. When the train speed is constant, the spatial distribution can also be equivalently converted into time distribution. The temporal and spatial distribution calculation of the hat-shaped gust model includes solving the time constant and the longitudinal and transverse wind speeds relative to the line. The temporal and spatial distribution of the hat-shaped gust model is as follows: Figure 3 As shown;

[0065] The time constant T is calculated by the power spectral density of the longitudinal component, and the formula is as follows:

[0066]

[0067] Where: is the average time constant; S u (n) is the power spectrum density; n is the frequency range of the calculated or measured data, and n is calculated as [1 / 3000Hz, 1Hz]; v mean is the average wind speed, and v is calculated mean =v max G, where G is the gust factor, G = 1.4016; σ uis the standard deviation of wind speed; f u is the dimensionless frequency; is the turbulence integral scale, and the statistical value measured at a ground height of 4 m is used for calculation;

[0068] Longitudinal wind speed u relative to the line x , lateral wind speed u y Calculated by time constant and wind direction angle, the formula is as follows:

[0069]

[0070] Where: x is the distance from the wind load point to the maximum gust amplitude; β w is the wind direction angle;

[0071] The correlation of gusts is expressed by a coherence function, which satisfies the following exponential decay curve:

[0072]

[0073] Where: Coh represents the coherence function; C ux , C uy All are coefficients, and C is used for calculation. ux =5, C uy =16;

[0074] According to the dynamic gust wind speed v w The gust wind speed v is calculated by adding the steady wind speed and the fluctuating wind speed w , the formula is as follows:

[0075] v w =v mean +2.5σ u Coh

[0076] The minimum wind speed of the dynamic gust model can only approach the average wind speed v infinitely. mean , when calculating wind speed and v mean When the error between is less than 1%, it can be considered that the exponential decay reaches the lower limit, and the complete distribution of the dynamic gust model can be obtained by symmetric processing about the longitudinal y axis;

[0077] The temporal and spatial distribution of the dynamic gust model can be divided into 6 stages, namely: t0<t<t1 is a windless state, t1<t<t2 is a linear rising state, t2<t<t3 is an average wind speed state, t3<t<t5 is an exponential rising and decaying state, t5<t<t6 is an average wind speed state, and t6<t<t7 is a linear decaying state. The calculation formula is as follows:

[0078]

[0079] Where: v w(t) is the dynamic gust wind speed function; t0, t1, t2 t7 are time points.

[0080] 3) Establishment of vehicle-track coupling model

[0081] like Figure 5 As shown, in the vehicle model, the car body, bogie and wheelset can be regarded as rigid bodies, and their longitudinal, lateral, sinking and floating, rolling, nodding and shaking 6 degrees of freedom are considered respectively, and a multi-rigid body vehicle system model with multiple degrees of freedom is established; the car body and the bogie are connected by a secondary suspension, and the wheelset and the bogie are connected by a primary suspension, and the nonlinear characteristics of the secondary lateral shock absorber, anti-snaking shock absorber and lateral stop are fully considered; the car body and the wind resistance brake device are integrated and embedded in the lateral center position of the roof of the car body. The whole vehicle layout of the wind resistance brake device is adapted to the relevant technical requirements of the Chinese standard EMU train. The installation base of the wind resistance brake device is required to achieve a smooth fit transition with the streamlined shape of the train after installation. The layout position of the wind resistance brake device on the roof of the head car is referenced Figure 7 ; Wheel-rail creep is nonlinear, and the solution of the wheel-rail normal force adopts the Hertz nonlinear elastic contact theory. The wheel-rail creep force is calculated according to the Kalker linear theory and nonlinear correction is made; the impact of track unevenness excitation on the safety of train wind resistance braking operation under gusts is not considered.

[0082] 4) Gust aerodynamic load loading and calculation

[0083] 41) Gust aerodynamic load loading: When calculating, the wind load is simplified into a concentrated force system acting on the vehicle body, which at least includes longitudinal force, lateral force, lift, rolling moment, nodding moment, and yaw moment. The action point of the concentrated force system is located at the center of the longitudinal direction of the two bogies and the intersection of the track centerline and the track surface, which is consistent with the calculation origin of the aerodynamic load coefficient in step 13);

[0084] 42) Calculation of gust aerodynamic loads: The aerodynamic force and aerodynamic moment are calculated as follows:

[0085] Where: i = x, y, z

[0086] At the same time, the vector relationship between the synthetic wind speed slip angle, wind speed, vehicle speed and wind direction angle satisfies the following formula:

[0087]

[0088] Where: v t is the train running speed; w is the wind direction angle; ρ is the air density; v a is the resultant velocity; β(t) is the slip angle, which is related to time t; are the aerodynamic force and moment coefficients respectively, which are related to the sideslip angle β(t); S is the characteristic cross-sectional area of ​​the train; d is the characteristic length of the train; the characteristic cross-sectional area and the characteristic length of the train are calculated using unified standard values ​​based on the test vehicle model.

[0089] 5) Derailment and operation safety domain determination of high-speed train wind resistance braking vehicles under gusts

[0090] 51) Selection of safety evaluation criteria for wind resistance braking of high-speed trains: The safety evaluation criteria for wind resistance braking of high-speed trains under gusts should at least include the wheel-rail vertical force P, wheel-rail lateral force Q, wheel-axle lateral force H, derailment coefficient Q / P, wheel load reduction rate ΔP / P, overturning coefficient D, and vehicle body lateral displacement Y. c 、Rolling angle displacement of vehicle body φ c ;

[0091] The index limits corresponding to the safety judgment criteria for wind resistance braking operation are as follows: wheel-rail vertical force P≤170kN; wheel-rail lateral force Q≤0.4(P st1 +P st2 ), P st1 , P st2 are the static loads of the left and right wheels respectively, and P is taken as st1 +P st2 The train axle weight is 17t; the wheel axle lateral force H≤(10+P0 / 3), P0 is the static axle weight; the derailment coefficient Q / P≤0.8; the wheel load reduction rate ΔP / P≤0.8; the overturning coefficient D=(P2-P1) / (P2+P1)≤0.8, P1 and P2 are the wheel-rail pressures on the inner and outer rail sides of the vehicle respectively; the vehicle body lateral displacement Y c and the vehicle body roll angle displacement φ c The corresponding safety index limits are determined by testing the vehicle technical standards.

[0092] 52) Determination of the most dangerous derailment wheelset under gusts: According to the motion posture of each wheelset of the train under the action of wind load, determine the wheelset of the vehicle that will derail first corresponding to each evaluation criterion during the gust loading time;

[0093] 53) Determination of high-speed train derailment and safety area: Based on the most dangerous derailment wheel determined in step 52), according to the high-speed train windage braking operation safety evaluation criteria proposed in step 51), the high-speed train windage braking derailment and safety area under the combined effect of three key factors: vehicle speed, wind speed, and wind direction angle are comprehensively calculated, and the train windage braking operation safety critical surface and derailment critical surface including vehicle speed, wind speed, and wind direction angle are drawn to determine the windage braking operation safety area, warning area, and derailment area.

[0094] 6) Verification of the evaluation method: Compare the derailment and safety areas in the gusty environment with the test train in the non-wind resistance braking operation state to determine whether there is an area where the wind resistance braking operation exceeds the limit range. If so, return to recalculate and determine.

[0095] The method of the present invention is used to calculate the t =200km / h,β w =90°,v max =15m / s, the change of the vehicle wind resistance braking operation safety limit index with gust loading time is as follows Figure 8 As shown in the figure, the vehicle wind resistance braking operation safety limit index changes with vehicle speed as shown in the figure. Fig. 9 As shown; considering the three key factors of vehicle speed, wind speed and wind direction angle, the method of the present invention is used to calculate the derailment / safety domain of the vehicle during the wind resistance braking operation under the hat-shaped gust environment. Fig.10 shown.

[0096] It should be noted that the directions or positional relationships indicated by “front”, “rear”, “left”, “right”, etc. mentioned in this document are based on the positional relationships 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 element referred to must have a specific direction, be constructed or operate in a specific direction. Therefore, it cannot be understood as a limitation on the technical solution, and the connection relationship may refer to a direct connection relationship or an indirect connection relationship. The professional terminology symbols in this document are given corresponding marks and explanations in the order of appearance, and are only explained once, and the same applies to the meanings, explanations or descriptions represented by the symbols with the same marks that appear later (including the drawings in the specification).

[0097] Obviously, those skilled in the art can make various changes and modifications 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 their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for safety assessment of wind resistance braking operation of high-speed trains in gusty environments, characterized by: The method aims at the wind resistance braking operation safety and derailment boundary of a high-speed train equipped with a wind resistance braking device in a strong gust environment, based on testing the aerodynamic load coefficient of the high-speed train under the action of stable wind in multiple working conditions, creating a double-exponential dynamic gust model according to the spatiotemporal distribution state of the gust, establishing a dynamic derailment model of the high-speed vehicle and track coupling under the action of gusts, and comprehensively comparing and calculating the various derailment evaluation criteria indicators of the high-speed train through multi-body dynamics simulation calculation of the wind resistance braking of the high-speed train under the action of gust loads, and determining the derailment and operation safety domain of the wind resistance braking vehicle of the high-speed train in the gust environment under the consideration of the safety margin; The safety assessment method for high-speed train wind resistance braking operation in a specific gust environment includes the following steps: 1) Determination of aerodynamic loads on high-speed trains equipped with windage brakes 11) Test model: The test model of the high-speed train equipped with a wind resistance brake device adopts a standard vehicle model consisting of a lead car with the worst running stability in a windy environment and a half-section auxiliary car body, and the lead car is equipped with a set of wind resistance brake devices; the wind resistance brake device is installed in the front 1 / 2 position section of the roof smooth section behind the driver's cab of the lead car; when establishing the wind resistance brake device model, structures with a full size less than 25mm can be ignored; the standard ground configuration model is a single-line ballastless track; 12) Determination method: The aerodynamic load of a high-speed train equipped with a wind resistance brake can be determined by wind tunnel test or computer numerical simulation; 13) Test determination content: Based on the standard vehicle model and the standard ground configuration model described in step 11), the aerodynamic load coefficients of the wind resistance brake device corresponding to the working posture under the action of uniform wind at different slip angles of 0° to 90° are calculated respectively, including the longitudinal force coefficient, lateral force coefficient, lift coefficient, rolling moment coefficient, nodding moment coefficient, and sideslip moment coefficient, and the sideslip angle-coefficient table is completed. The calculation origin of the aerodynamic load coefficient is located at the center of the longitudinal direction of the two bogies and the intersection of the track centerline and the track surface; the calculation gradient of the slip angle is not greater than 5°; the general form of the sideslip angle-coefficient table is as follows: 2) Dynamic gust model establishment The hat-shaped gust model is used in the calculation to approximate the dynamic wind field. The hat-shaped gust model is described by spatial distribution. When the train running speed is constant, the spatial distribution can also be equivalently converted into time distribution. The time and space distribution calculation of the hat-shaped gust model includes solving the time constant and the longitudinal and transverse wind speeds relative to the line. The time constant T is calculated by the power spectral density of the longitudinal component, and the formula is as follows: Where: is the average time constant; S u (n) is the power spectrum density; n is the frequency range of the calculated or measured data, and n is calculated as [1 / 3000Hz, 1Hz]; v mean is the average wind speed, and v is calculated mean =v max / G, where G is the gust factor, G = 1.4016; σ u is the standard deviation of wind speed; f u is the dimensionless frequency; is the turbulence integral scale, and the statistical value measured at a ground height of 4 m is used for calculation; Longitudinal wind speed u relative to the line x , lateral wind speed u y Calculated by time constant and wind direction angle, the formula is as follows: Where: β is the distance from the wind load action point to the maximum gust amplitude; w is the wind direction angle; The correlation of gusts is expressed by a coherence function, which satisfies the following exponential decay curve: Where: Coh represents the coherence function; C ux , C uy All are coefficients, and C is used for calculation. ux =5, C uy =16; According to the dynamic gust wind speed v w The gust wind speed v is calculated by adding the steady wind speed and the fluctuating wind speed w , the formula is as follows: v w =v mean +2.5σ u Coh The minimum wind speed of the dynamic gust model can only approach the average wind speed v infinitely. mean , when calculating wind speed and v mean When the error between is less than 1%, it can be considered that the exponential decay reaches the lower limit, and the complete distribution of the dynamic gust model can be obtained by symmetric processing about the longitudinal y axis; 3) Establishment of vehicle-track coupling model In the vehicle model, the car body, bogie and wheelset can be regarded as rigid bodies, and their longitudinal, lateral, sinking and floating, rolling, nodding and shaking degrees of freedom are considered respectively, and a multi-rigid body vehicle system model with multiple degrees of freedom is established; the car body and the bogie are connected by a secondary suspension, and the wheelset and the bogie are connected by a primary suspension, and the nonlinear characteristics of the secondary lateral shock absorber, anti-snaking shock absorber and lateral stopper are fully considered; the car body and the wind resistance brake device are integrated and embedded in the lateral center position of the roof of the car body. The vehicle layout of the wind resistance brake device is adapted to the relevant technical requirements of the Chinese standard EMU train. The installation base of the wind resistance brake device is required to achieve a smooth fit transition with the streamlined shape of the train after installation; the wheel-rail creep is nonlinear, and the solution of the wheel-rail normal force adopts the Hertz nonlinear elastic contact theory, and the wheel-rail creep force is calculated according to the Kalker linear theory and nonlinear correction is made; the influence of track unevenness excitation on the safety of train wind resistance braking operation under gusts is not considered; 4) Gust aerodynamic load loading and calculation 41) Gust aerodynamic load loading: When calculating, the wind load is simplified into a concentrated force system acting on the vehicle body, which at least includes longitudinal force, lateral force, lift, rolling moment, nodding moment, and yaw moment. The action point of the concentrated force system is located at the center of the longitudinal direction of the two bogies and the intersection of the track centerline and the track surface, which is consistent with the calculation origin of the aerodynamic load coefficient in step 13); 42) Calculation of gust aerodynamic load: aerodynamic force F i (t) and aerodynamic moment M i (t) is calculated as follows: Where: i = x, y, z At the same time, the vector relationship between the synthetic wind speed slip angle, wind speed, vehicle speed and wind direction angle satisfies the following formula: Where: v t is the train running speed; β w is the wind direction angle; ρ is the air density; v a is the resultant velocity; β(t) is the slip angle, which is related to time t; are respectively the aerodynamic force and moment coefficient, which are related to the sideslip angle β(t); S is the characteristic cross-sectional area of ​​the train; d is the characteristic length of the train; the characteristic cross-sectional area of ​​the train and the characteristic length of the train are calculated by taking the unified standard value according to the test model; 5) Derailment and operation safety domain determination of high-speed train wind resistance braking vehicles under gusts 51) Selection of safety evaluation criteria for wind resistance braking of high-speed trains: The selection of safety evaluation criteria for wind resistance braking of high-speed trains under gusts should at least include the wheel-rail vertical force P, wheel-rail lateral force Q, wheel-axle lateral force H, derailment coefficient Q / P, wheel load reduction rate ΔP / P, overturning coefficient D, and vehicle body lateral displacement Y. c 、Rolling angle displacement of vehicle body φ c ; 52) Determination of the most dangerous derailment wheelset under gusts: According to the motion posture of each wheelset of the train under the action of wind load, determine the wheelset of the vehicle that will derail first corresponding to each evaluation criterion during the gust loading time; 53) Determination of high-speed train derailment and safety area: Based on the most dangerous derailment wheel determined in step 52), according to the high-speed train windage braking operation safety evaluation criteria proposed in step 51), the high-speed train windage braking derailment and safety area under the combined effect of three key factors: vehicle speed, wind speed, and wind direction angle are comprehensively calculated, and the train windage braking operation safety critical surface and derailment critical surface containing vehicle speed, wind speed, and wind direction angle are drawn to determine the windage braking operation safety area, warning area, and derailment area; 6) Verification of the evaluation method: Compare the derailment and safety areas in the gusty environment with the test train in the non-wind resistance braking operation state to determine whether there is an area where the wind resistance braking operation exceeds the limit range. If so, return to recalculate and determine.

2. The method for safety assessment of wind resistance braking operation of high-speed trains in gusty environments according to claim 1 is characterized in that: The temporal and spatial distribution of the dynamic gust model can be divided into 6 stages, namely: t0<t<t1 is a windless state, t1<t<t2 is a linear rising state, t2<t<t3 is an average wind speed state, t3<t<t5 is an exponential rising and decaying state, t5<t<t6 is an average wind speed state, and t6<t<t7 is a linear decaying state. The calculation formula is as follows: Where: v w (t) is the dynamic gust wind speed function; t0, t1, t2…t7 are time points.

3. The method for safety assessment of wind resistance braking operation of high-speed trains in gusty environments according to claim 1 is characterized in that: The index limits corresponding to the safety judgment criteria for wind resistance braking operation are as follows: wheel-rail vertical force P≤170kN; wheel-rail lateral force Q≤0.4(P st1 +P st2 ), P st1 , P st2 are the static loads of the left and right wheels respectively, and P is taken as st1 +P st2 The train axle weight is 17t; the wheel axle lateral force H≤(10+P0 / 3), P0 is the static axle weight; the derailment coefficient Q / P≤0.8; the wheel load reduction rate ΔP / P≤0.8; the overturning coefficient D=(P2-P1) / (P2+P1)≤0.8, P1 and P2 are the wheel-rail pressures on the inner and outer rail sides of the vehicle respectively; the vehicle body lateral displacement Y c and the vehicle body roll angle displacement φ c The corresponding safety index limits are determined by testing the vehicle technical standards.

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