Experimental and theoretical study of shock wave propagation through double-bend ducts

The complex flow and wave pattern following an initially planar shock wave transmitted through a double-bend duct is studied experimentally and theore tically/numerically. Several different double-bend duct geometries are inve stigated in order to assess their effects on the accompanying flow and shoc k wave attenuation while passing through these ducts. The effect of the duc t wall roughness on the shock wave attenuation is also studied. The main ho w diagnostic used in the experimental part is either an interferometric stu dy or alternating shadow-schlieren diagnostics. The photos obtained provide a detailed description of the flow evolution inside the ducts investigated . Pressure measurements were also taken in some of the experiments. In the theoretical/numerical part the conservation equations for an inviscid, perf ect gas were solved numerically. It is shown that the proposed physical mod el (Euler equations), which is solved by using the second-order-accurate, h igh-resolution GRP (generalized Riemann problem) scheme, can simulate such a complex, time-dependent process very accurately. Specifically, all wave p atterns are numerically simulated throughout the entire interaction process . Excellent agreement is found between the numerical simulation and the exp erimental results. The efficiency of a double-bend duct in providing a shoc k wave attenuation is clearly demonstrated.