| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 92 === In this study, the problem of a planar reflected shock/vortex interaction near an open-ended duct is considered. The reflected shock is developed after exiting the duct and impinging on a flat plate that is downstream of the duct. Two cases associated with the shock diffraction around the duct end are investigated for understanding the detailed flow structure and noise production due to the reflected shock/vortex interaction. One is a 90-degree diffraction; the other is a 180-degree diffraction. An Euler solver with a high-resolution scheme of weighted essential non-oscillation is used to study these complicated flow problems. The Euler solver is validated for the accuracy of numerical solutions with experimental data. For the study of the reflected shock/vortex interaction, the techniques of computational shadowgraph, schlieren image, and interferography are used. Detailed flow structures of reflected shock/vortex interactions are reported for different incident shock Mach numbers. An interesting result of a stagnant reflected shock wave downstream of the duct end is found for an incident shock Mach number equal to or greater than 1.4. For the incident shock Mach number below this critical value, the reflected shock will eventually enter the duct. Finally, the corresponding ring vortex is included for comparison with the planar case. It is found that the pressure increase at the vortex center due to the reflected shock in the axi-symmetric problem is less than that in the corresponding planar case .
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