Study On Aerodynamic Performance Of High-speed Trains Through The Tunnel

With the continuous raising of train speed, the aerodynamic problems caused by the train entering into a tunnel become more and more serious. The compression wave and expansion wave induced by train entering into a tunnel makes significant pressure fluctuations inside the tunnel, it will directly affect the comfort of passengers, safety and stability of train、surrounding environment of the tunnel. In addition, the excessive pressure will have a great influence on the strength of train material. The aerodynamics and calculation of multi-body system dynamics were combined to study aerodynamic performance of high-speed train under the tunnel. Besides the influence of aerodynamic load on structure strength was analyzed.First of all, based on the three-dimensional time related viscous compressible fluid Reynolds average Navier-Stokes equations and k-e two-equations turbulent model, flow field calculational model of single train passing through tunnel and two trains passing by in tunnel was built by using CFD software FLUENT, then analyses the influence of speed and length of train on the pressure and force. Secondary, based on the theory of multi-body system dynamics, using software SIMPACK to build a multi-body system dynamic model, on which the aerodynamic loads are dealt with as external loads to study the influence of speed of train, length of train, different traffic on the safety and stability of train. Finally, loading the transient aerodynamic pressure onto the surface of train, then analyses the influence of aerodynamic load on structure strength, and get the response time curve of train.This study can give the following results:1. During the train pass through the tunnel, propagation and reflection of compression wave and expansion wave result in the complex change of pressure; the amplitude of pressure and square of speed is approximately inversely proportional relationship;2. The length of train has great effect of aerodynamic performance on the tail of train, but no effect on the head of train;3. During the two trains passing by in tunnel with350km/h, the pressure of amplitude on the train is about eight times of trains passing by on the open ground; the safety and stability of train is better than that of passing by on the open ground;4. Lateral displacement and stress of sidewall of train changes intensely under the transient aerodynamic pressure, and the amplitude of windows is larger than that of doors.