Investigation on dynamic performance of high-speed trains under tunnel and crosswind environment considering car-body flexibility based on a CFD-MBD co-simulation method

The dynamic performance of railway vehicles is significantly impacted by sudden-changed aerodynamic loads. To investigate the dynamic performance of high-speed trains (HSTs) under tunnel and crosswind environments considering the car-body flexibility, an intensive study is conducted. First, a train–track interaction dynamic model with a flexible car body is established in SIMPACK for dynamic response analysis. Concurrently, an aerodynamic model for calculating the distribution of aerodynamic loads is found in FLUENT to determine forces and moments applied to each part of the car body. Then, the two models are coupled utilizing a co-simulation method developed based on the User Data Protocol (UDP). Finally, a case study is carried out, involving a train passing through tunnels subjected to crosswinds. The results reveal that the distribution of aerodynamic loads on the car-body affected by crosswind is time-variant and non-even. Interestingly, the dynamic simulation results are almost unaffected by the method used to allocate the loads on the car body. Variations in the aerodynamic loads affected by crosswinds lead to flexible first-order diamond mode vibration of the car body at around 8.5[Formula: see text]Hz when exiting the tunnel. As the crosswind speed continues to increase, vibrations at frequencies of 18.2[Formula: see text]Hz and 24.2[Formula: see text]Hz will be enhanced, corresponding to the bending mode and combined mode of the car body. However, similar flexible vibrations are insignificant when the vehicle enters the tunnel. In addition, the vertical wheel–rail interaction obtained by the dynamic model with a rigid car body is slightly greater than that with a flexible car body.