Experimental and Numerical Studies on Vortical Flows Induced by Shock Wave Focusing over Parabolic Reflectors

• Main Authors: Wu, Long-Nany, 吳龍男
• Other Authors: Shen-Min Liang
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/59877377804938454098

博士 === 國立成功大學 === 航空太空工程學系 === 85 === The problem of a plane shock wave propagating in an air media over atwo-dimensional/axisymmetric parabolic reflectors is considered. Theshock wave after reflecting from the parabolic concave reflector formsa converging concave shock wave. The converging cancave reflected shockwave will focus at later time and results in a complicated flow fieldwith multiple vortices. The focused shock wave can greatly magnify thepressure and the temperature, and induce vortical flows. The purposeof this study is to investigate the phenomenon of vortical flowsinduced by shock wave focusing and to understand the mechanism of thevortex formation through Experimental Fluid Dynamic (EFD) and Computational Fluid Dynamic (CFD) method. The EFD technique is toemploy a shock tube equipment to generate planar incident shockwave, that reflects from parabolic reflector and focuses at gasdynamicfocus. The color schlieren optical photography is used to record theimages of the flow fields. The piezo-electric pressure transducers areused to measure the dynamic pressures. The implicit upwind TVD schemewith an improved flux limiter is used to simulate the problem ofinterest. The real-gas-effect is taken into account through a propercorrection of the specific heat ratio of air. The implosion phenomenonis also investigated.