ScholarWorks@한국철도기술연구원

초록

Compression waves generated due to piston action of a high-speed train entering tunnel is a well-established phenomenon. However, this process is accompanied by the emission of an impulse wave from the tunnel entrance, known as the entry impulse wave (EIW). The EIW’s amplitude is directly proportional to the pressure gradient of the entry compression wave. While EIWs are weaker than the micro-pressure waves discharged from the tunnel exit, they can potentially cause environmental disturbances, especially at higher train speeds. The current study uses numerical and aero-acoustical analyses to understand the characteristics of EIW under varying conditions, including train speed, blockage ratio, and tunnel length. Results show that the maximum value of the EIW gradually increases with increase in train speeds and higher blockage ratios. In longer tunnels, the higher acoustic impedance value results in an exponential rise in the amplitude of the entry impulse wave (EIW).