Multistep train nose for reducing micro-pressure waves

Abstract

The peak value of a micro-pressure wave radiating from tunnel portals of high-speed railways depends on the shape of the train nose. Previous studies have shown that a train nose shape with a small gradient of cross-sectional area distribution, except at the tip and end, is effective at reducing micro-pressure waves. Using acoustic theory, this study showed that multistep train noses are more effective at reducing micro-pressure waves than the previously suggested nose shapes. Moreover, the multistep noses were optimized using the response surface method and computational fluid dynamics techniques for axisymmetric compressible airflow. In addition, model experiments were performed to verify the usefulness of the optimized multistep noses. The optimized multistep noses reduced the peak values of the micro-pressure wave by over 5% compared to the previous noses. Thus, this study theoretically, numerically, and experimentally suggests new optimal nose shapes that can better reduce micro-pressure waves than existing shapes.