Reducing Micro-pressure Waves Using Train Nose Optimization Based on Linear Acoustic Theory

Abstract

The shapes of train noses have been optimized for several decades to reduce the peak values of the micro-pressure waves radiating from tunnel portals of high-speed railways. This study optimized the shapes of multistep noses using three transfer functions based on the theory of compact Green's function (W_T ), experimental results (W_E ), and the average value of W_T and W_E (W_M ). Model experiments were performed to measure the maximum pressure gradients of compression waves generated by each train nose entering a tunnel for offset running. For optimized train noses based on W_T or W_E , the values of the maximum pressure gradient could not be sufficiently reduced, and the pressure gradient waveforms were not trapezoidal. Although the optimized noses based on W_M reduced the maximum pressure gradients considerably, the maximum pressure gradient values were larger than those for the optimized noses based on the computational fluid dynamics.