Investigation on Unsteady Interaction Phenomena of Shock Waves and Turbulent Boundary Layers in Supersonic Internal Flows

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Experimental and numerical investigations on the supersonic internal flows with shock waves, i.e., so called Pseudo-Shock Wave ( PSW) phenomena in rectangular ducts related to scramjet engine isolators and intakes, were conducted. Experimental results are summarized as follows:(1) The location, internal structure and characteristic of the Mach 2 and 4 PSWs were investigated by color shlieren photographs and duct wall pressure fluctuation measurements. As the results, it was revealed that in the case of uniform flow Mach number M∞= 2, λ-type PSW with symmetric geometry occurs in the square duct. In the case of Mach number M∞= 4, an X-type PSW occurs in the duct, and an asymmetric flow which deviates greatly to top or bottom wall appears.(2) In the case of M_∞= 2, large wall pressure fluctuations due to the PSW oscillations occur under the first shock wave of the PSW, while in the case of M_∞= 4, the large wall pressure fluctuations occur under the first and second shock waves of the PSW … More .(3) The wall shear stresses in PSWs were visualized qualitatively by shear-sensitive liquid crystal, and measured quantitatively by the hand made shear stress transducer. As the results, it was revealed that in the case of Mach 4 PSW reverse flows exist in the top wall boundary layer separation region, and that the separated boundary layer on the top wall is reattached, and how the magnitude of the wall shear stress change in the PSW. It was also revealed that the bottom wall boundary layer separates widely in the PSW and the reverse flow exist in the separation region.Numerical simulations were carried out using the Harten-Yee second order TVD scheme and the Baldwin-Lomax turbulence model. Numerical results are summarized as follows:(4) The computational results for the Mach 2 PSW are in good agreement with the experimental results.(5) In the case of Mach 4 PSW, the several differences were found between the computational results and experiments due to asymmetric characteristics in the experiment which could not be reproduced in the simulation. However, the computational results are valuable for understanding the complex asymmetric phenomena. Less