For the improvement of the sound environment around a portal of a high speed train tunnel, model experiments for the reduction of MPW (Micro-Pressure Wave) have been studied. In order to reduce the level of MPW, a control wave, that is a positive pressure, is generated at a side-branch in a model tunnel and is superposed on the incident wave front of a compression wave propagating through the tunnel. The method of active reduction of MPW and experimental equipment are shown. Characteristics of the wave forms of the compression wave and the control wave with suitably designed servo actuators were examined. The experimental results of the reduced level of MPW agreed well with numerical calculation results.
References
1.
VardyA. E., Reflection of Step-Wavefronts from Perforated and Flared Tube Extensions, Journal of Sound and Vibration59, 577–589, 1978
2.
MinoruKOBAYASHIYasufumiSUZUKIKatsuoriAKITSU and SatoruOZAWA, Analysis of Pressure Changes Developed Outside and Inside a Shinkansen Train Running through a Tunnel (in Japanese), Transactions of the Japan Society of Mechanical Engineers61–591, 256–262, 1995
3.
YamamotoA., Micro-Pressure Wave Radiated from Tunnel Exit (in Japanese), Physical Society of Japan1977, 4P-H4, 1977
4.
TatsuoMAEDA, Reduction of Micro-pressure Wave Radiated from Tunnel Exit by Branches in Tunnel, The Railway Technical Research Report of Japanese National Railways 1167, 1981
5.
SatoruOZAWA, Studies of Micro-pressure Wave Radiated from a Tunnel Exit (in Japanese), Railway Technical Research report of Japanese National Railways1121, 1–92, 1979
6.
SatoruOZAWAKyoichiTSUKAMOTOTatsuoMAEDA, Model Experiments on Devices to Reduce Pressure Wave (in Japanese), Railway Technical Research Report of Japanese National Railways990, 1976.
7.
SatoruOZAWAToshitakaUCHIDATatsuoMAEDA, Reduction of Tunnel Exit Boom by Hood at Tunnel Entrance (Experiments at Bingo Tunnel in Shinkansen), The Railway Technical Research Report of Japanese National Railways1054, 1977
8.
NishimuraMasaharuKondoMotoeIwamotoKengo and TujimotoYoshikazu, Active Attenuation of Impulsive Noise from a Railway Tunnel Exit, Inter Noise94, 1382–1388, 1994
9.
A Study of Negative Impulsive Wave Generator for Reducing Impulsive Noise (Improvement of Wave Strength) (in Japanese), Transactions of the Japan Society of Mechanical Engineers62–601, 1996
10.
Development of Active Silencer against Micro-Pressure Wave at Shinkansen Tunnel Exit (in Japanese), Katsushi MATSUBAYASHI, Toshifumi KOSAKA, Toshiya KITAMURA, Shinji YAMADA, The Acoustical Society of Japan, Report of the 1993 Autumn Meeting, 731–732, 1993
11.
KatsushiMATSUBAYASHIToshifumiKOSAKA, Researches and a Control Plan on Compression Wave and Micro-Pressure Wave at Shinkansen Tunnel Exit (in Japanese), Research Report 1994, Tokyo National College of Technology, 1994
12.
KatsushiMATSUBAYASHIToshifumiKOSAKAToshiyaKITAMURAShinjiYAMADA, On Generating System of Compression Wave for the Reduction of Micro-Pressure Wave, The Institute of Noise Control Engineering Japan, Proceedings of the 1996 Meeting, 375–378, 1996
13.
KatsushiMATSUBAYASHIAlanVARDYJimBROWN, Active Control of Incident Wave Front of Compression Wave in Tunnel to Reduce the Level of Micro-pressure Wave (in Japanese), Transactions of the Japan Society of Mechanical Engineers 68–673 C, 2002
14.
LiangMinKitamuraToshiyaMaedaTatsuoYamadaSatoshiKosakaToshifumiMiyataKatsufumji and YamadaShinji, Active Attenuation of Tunnel Pressure Wave with Negative Pressure Gradient Generated by Positive Pressure, The Journal of the Acoustical Society of Japan (E), Vol.16No.6, 363–369, 1995
