Journal ArticleDOI
Attenuation of weak shock waves along pseudo-perforated walls
Akihiro Sasoh,Kei Matsuoka,K. Nakashio,E. Timofeev,Kazuyoshi Takayama,P. Voinovich,T. Saito,S. Hirano,S. Ono,Y. Makino +9 more
TLDR
In this paper, the effects of 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.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.read more
Citations
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Journal ArticleDOI
Numerical study of shock-wave mitigation through matrices of solid obstacles
TL;DR: In this paper, the authors analyze the control mechanism for shock propagation and attenuation in complex inhomogeneous and porous medium, particularly at lower effective flow area, where the frictional forces are expected to be important.
Journal ArticleDOI
Experimental investigation on the shock-wave load attenuation by geometrical means
TL;DR: In this article, the authors investigated the effect of the obstacle geometry on the load development in a single-obstacle setup and found that the effect becomes dominant when the blockage ratio (i.e., ratio of the non-open area to the overall cross section) is large.
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Oblique tunnel portal effects on train and tunnel aerodynamics based on moving model tests
TL;DR: In this article, the effects of oblique tunnel portals on train and tunnel aerodynamics using a 1:20 scale moving model device were investigated using a pressure sensor and micro-pressure wave measured using pressure sensors.
Journal ArticleDOI
A moving model rig with a scale ratio of 1/8 for high speed train aerodynamics
TL;DR: In this paper, a train model in a moving model rig (MMR) was developed for the acceleration, testing, and deceleration of a high speed train model along opposite directions, and two train models weighing 265 and 106 kilograms can be accelerated to speeds of 401 and 507 km/h, respectively, within a brake distance of 70 m.
Journal ArticleDOI
Influence of tunnel aerodynamic effects by slope of equal-transect ring oblique tunnel portal
TL;DR: In this paper, the authors used a three-dimensional, compressible, turbulence model to investigate the alleviation effect on tunnel aerodynamics of equal-transect ring oblique tunnel portals with different slope values.
References
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Proceedings ArticleDOI
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Journal ArticleDOI
Experimental investigation on tunnel sonic boom
TL;DR: In this article, a 1∶300 scaled train tunnel simulator was constructed and simulation experiments were carried out using this facility to investigate the generation of weak shock wave in train tunnels and the emission of the resulting sonic boom from the train tunnel exit and to search for methods for the reduction of these sonic booms.