Attenuation of weak shock waves along pseudo-perforated walls |
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Authors: | A Sasoh K Matsuoka K Nakashio E Timofeev K Takayama P Voinovich T Saito S Hirano S Ono Y Makino |
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Institution: | (1) Shock Wave Research Center, Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-77, Japan , JP;(2) Nihon SiliconGraphics-Cray K.K., P.O.Box 5011, Yebisu Garden Place, 4-20-3, Ebisu, Shibuya, Tokyo 150, Japan , JP;(3) East Japan Railway Co., Tokyo Kotsu Kaikan 7th Floor, 2-10-1 Yuraku-cho, Chiyoda-ku, Tokyo 100, Japan , JP |
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Abstract: | In order to attenuate weak shock waves in ducts, effects of pseudo-perforated walls were investigated. Pseudo-perforated
walls are defined as wall perforations having a closed cavity behind it. Shock wave diffraction and reflection created by
these perforations were visualized in a shock tube by using holographic interferometer, and also by numerical simulation.
Along the pseudo-perforated wall, an incident shock wave attenuates and eventually turns into a sound wave. Due to complex
interactions of the incident shock wave with the perforations, the overpressure behind it becomes non-uniform and its peak
value can locally exceed that behind the undisturbed incident shock wave. However, its pressure gradient monotonically decreases
with the shock wave propagation. Effects of these pseudo-perforated walls on the attenuation of weak shock waves generated
in high speed train tunnels were studied in a 1/250-scaled train tunnel simulator. It is concluded that in order to achieve
a practically effective suppression of the tunnel sonic boom the length of the pseudo-perforation section should be sufficiently
long.
Received 23 June 1997 / Accepted 16 September 1997 |
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Keywords: | :Weak shock waves Sonic boom Railway tunnel Wall perforation Holographic interferometry |
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