Aerodynamic Characteristics And Dynamic Analysis Of Heavy Duty Freight Train Under Cross Wind

Now in our country,the train speed increases continuously,the strong wind environment especially the influence caused by the cross wind on the safe operation of the train is more and more significant,the heavy train in some areas of the Daqin Line has high winds,including the cross wind will greatly affect the operation state of the trains,and even cause the derailment accident.In this thesis,the heavy duty truck under cross wind is studied deeply,and the operation safety of the train is analyzed and studied by using the basic theory of fluid dynamics and multi-body system dynamics.In this thesis,3D design software SLIDWORKS is used to establish the train geometry model according to the real size of heavy duty train 1:1,and the model is imported into CFD(fluid dynamics)software FLUENT.After repair and simplification,the train CFD model is established.Using the Standard k-ε turbulence model to simulate and calculate the aerodynamic load of heavy-haul train at different speed and wind speed under cross wind,the flow field characteristics around the car body under the same working condition are analyzed and studied.It is found that there are obvious differences in the variation degree of aerodynamic load between the locomotive locomotive and the truck body under the same working condition due to the difference of geometric shape.It is found that the order of aerodynamic load in each working condition is: locomotive > truck 1> truck 2> truck 3.The aerodynamic load of each vehicle increases significantly with the increase of train speed and cross wind speed.Combined with the distribution diagram of train flow field,the distribution and variation trend of aerodynamic load are explained.Then,based on the theory of multi-body dynamics,the kinematic relationship and articulated type between the train connections during real train operation are analyzed,and the multi-body system dynamics model of heavy duty truck grouping is established by using MBSD(multi-body dynamics)software UM.The aerodynamic load measured by CFD model was applied to the multi-body dynamics model to study the linear and curved dynamic safety indexes of heavy duty trucks under two conditions of empty and heavy vehicles under cross-wind environment.The four dynamic indexes of derailment coefficient,wheel weight load reduction rate,axle lateral force and lateral stability were selected for the study.The simulation analysis was carried out when the speed of the train was 60～120k M/h and the wind speed was 10～25m/s.It was found that the safety indexes increased significantly with the increase of speed and wind speed when the train was in a straight line.Under the same working condition,the safety indexes of truck 1 among the three trucks were the lowest,and the safety indexes of the empty truck were generally greater than those of the heavy car model under the same working condition.When the wind speed is 25m/s,the wheel weight reduction rate index of truck 1 and truck 2 in empty condition exceeds the limit value,and there is the risk of derailment.In curve working condition,each dynamic index increases significantly compared with that in straight working condition and also increases with the increase of speed and wind speed.In the same working condition,the safety of truck 1 is the lowest,and the operation safety of heavy truck is higher than that of empty car.The maximum safe cross wind speed of empty and heavy car in line with the safety limit is analyzed and studied under each curve working condition.The research shows that:under the linear and curved lines,the influence of cross wind on the dynamic performance index of heavy duty train is more obvious,and the influence is the most obvious in the curve condition,so it is necessary to consider the influence caused by cross wind when studying the dynamic performance index of heavy duty train.