Aided Engineering Measures On The Tunnel Aerodynamic Effects

Obvious pressure fluctuation in tunnel and micro-pressure wave radiated from the exit of the tunnel, which are caused by a train entry into a tunnel at a high speed, will make serious impact on driving safety, passenger riding comfort and environment around a tunnel. Therefore, it is basic question that must be considered when related to the high-speed railway-tunnel designs and whether exist tunnels adapt to the speed-raising of train.In order to simulate the complex airflow inner tunnel truly, the Navier-Stokes equations with three dimensional, compressible and unsteady viscous fluid were taken as the control equations, the movement between train and tunnel, and two tains was implemented by adopting the technology named slippage grid. Then, the assistant measures which can alleviate the tunnel aerodynamics effect were studied systemicly combining with the model experiment, and some important conclusions were gained as following:The aerodynamic effect was alleviated effectively because of the assistant estalishments of tunnel (shaft, cross passage). Air pressure amplitude of measuring points on train surface and tunnel wall is approximately proportional to the square of running speed of the train, and micro- pressure wave is approximately proportional to the cube of running speed of train after setting the assistant establishments.The position, cross-section area and number of the shaft take an important role in decreasing the areodynamics pressure amplitude, and there are the idealist values for the three above,which are nearly ralational to parameter of the tunnel, the type and running speed of train. For example, when the train at the speed of 200km/h passes through the tunnel which cross-section area is 59m~2, and length is 986 meter, the idealist area of the shaft is 14m~2, and idealist number is 3.As similar as the shaft, the cross-section aera, spacing of cross passage and the spacing of parallel tunnel have significant influence on aerodynamics effects. There are also the idealist values for three above, and which are nearly ralational to the parameter of the tunnel, the type and running speed of train. The influence on pressure of measuring points on train surface and tunnel wall caused by the change of the cross passage shape is not obvious. However, for the micro-pressure, The alleviating effect of the cross passage with circle shape is better than the arched shape', and the former can decrease more 11.2% than the latter.