Study of Aerodynamic Noise induced by Shock Waves in Supersonic Flows and Development of a Method for Reducing the Noise

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1. To accomplish the railway tunnel simulator, a fast opening gate valve was developed. we analyzed the performance of the fast opening gate valve by using a super high-speed video camera. The results show that the opening time of the gate valve decreases when the initial pressure in the actuating chamber increases. And the relation between the initial pressure in the actuating chamber and the characteristics of the compression wave such as the maximum pressure gradient was made clear.2. To study the ballast effect on distortion of pressure wave propagating in high-speed railway tunnel, we made a high-speed railway tunnel simulator using a fast opening gate valve. An experimental investigation was carried out to clarify the distortion of a propagating compression wave in a model tunnel with various porous material wall. Experimental data shows the possibility of the present alleviative method, and the effects of the porous material wall is clear.3. The compression waveform in the propagating process are studied numerically by second-order symmetric TVD method scheme, taking both fluid friction on the flat wall and the effect of the ballasted track into consideration. The waveform of the compression wave in the tunnel calculated by the present two-layer method is in good agreement with that of the field test data on both track tunnels, so that the present numerical method of calculation seems to be reasonable.