Study On The Operation Stability Of Multiple Units Running In Or Out Of Tunnel Or Wind-shelter Under Crosswind

Crosswind has great influence on the stability of train operation.Especially with the continuous improvement of train speed and carbody lightweight,the problem of train running stability is more prominent under crosswind.When multiple units are running in or out of tunnel or wind-shelter,complex airflow characteristics at the entrance and exit of tunnel or wind-shelter will threaten the running stability of train.It should be noticed that the Lanzhou-Xinjiang High-speed Railway through the famous wind zone in Xinjiang,therefore,it is significant to study the operation stability of multiple units in and out of tunnel and wind-shelter under crosswind.The development of high-speed train in China and abroad were reviewed,and the research status of the operation stability of high-speed train in crosswind was summarized,The basic theory of multi rigid-body dynamics was briefly introduced,and a brief description of the three methods for formulating the differential equations of vehicle was gave out.The basic rules of high speed train system modeling were expounded,and the model diagrams of vehicle physical model were provided.The Multi-body dynamics software SIMPACK was briefly introduced,the Wheel/Rail module of SIMPACK and Wheel/Rail module’s basic modeling theory were stressed.The rules and assumptions for train modeling were listed,and the DOF of vehicle system model was analyzed.The bogie structures of multiple units A and multiple units B were presented,and the three car system dynamics models of multiple units A and multiple units B are constructed using SIMPACK as well.The nonlinear critical speeds of multiple units A and multiple units B models were calculated,and the track spectrum of Beijing-Tianjin railway line was adopted as the track irregularity.The difference between the coordinate system used in aerodynamic calculation and the system dynamics was analysised,and the application method of aerodynamic load was elaborated.Finally,the safety indexes of high speed train and the limits were introduced.The calculated aerodynamic load data were imported in the multiple units A and multiple units B system dynamics models.With the models,the operation stability of Multiple Unit runs in or out of tunnel or wind-shelter under crosswind was studied.The results show that under typical operating condition,multiple units A and multiple units B can stably exit wind-shelter.During multiple units A and multiple units B entering wind-shelter,the stability status of middle car of multiple units B’s operation is not good,while multiple units A’s operation status is stable and operational safety index values are similar to the values that when multiple units A entering wind-shelter.The aerodynamic loads act on the carbody are more violent when Multiple Units operating in and out of tunnels.The middle car of multiple units B and the tail car of multiple units A are not stable.When multiple units B multiple units run out of wind-shelter under different operating conditions,the dynamic performance of the middle car and the tail car is getting worse when the wind angles are 30 o and 90 o,the dynamic performance of the head car is gradually improved with the increase of wind angle,however the dynamic performance of vehicle is gradually getting worse with the increase of wind speed.The overturning coefficient,the wheelset load reduction ratio,the coefficient of derailment and the lateral wheelset force when the wind speed at the range of 30 to 40m/s.The dynamic performance of the middle car and the tail car is getting worse with the increase of train speed,while the head car’s dynamic performance is gradually improved.When the train speed is over 200km/h,the deterioration degree of the dynamic performance of the middle car and the tail car is increasing.The results also illustrate that influence of crosswind on the performance of running stability of Multiple Units under crosswind is mainly determained by the side force and rolling moment,and the influence of other forces and moments on the dynamic performance of multiple units A is greater than that of multiple units B.The present work on multiple units A and multiple units B multiple units running in or out of tunnel or Wind-shelter under crosswind may provide a reference to the stable operation of multiple units under crosswind.