Three-Dimensional Normal Shock-Wave/Boundary-Layer Interaction in a Rectangular Duct

摘要

The three-dimensional flow structure induced by normal shock-wave/turbulent boundary-layer interaction in a constant-area rectangular duct is investigated by a laser-induced-fluorescence method. This diagnostic system uses an argon-ion laser as a light source, and the target gas is dry nitrogen with iodine seeded as a fluorescence material. The Mach-number distributions in the duct are obtained from the measured fluorescence intensity, and the three-dimensional flow pattern in the expansion region downstream of the initial shock wave is clarified. In addition to this, the region having locally higher Mach number near the duct corners is observed immediately behind the shock wave, and the three-dimensional shape of the boundary layers is found. These flow characteristics are reproduced by solving the Navier-Stokes equations numerically. The calculated result reveals that the complicated shock-wave configuration is formed at the duct corner because of the interaction of two bifurcated shock waves developed on the two perpendicularly adjacent walls. The simple flow model is also constructed by considering this interaction. This model can explain very well the three-dimensional flow characteristics.