Abstract

Shock wave / boundary layer interactions are an important feature of high-speed flow that occur in supersonic and hypersonic aircraft inlets, aircraft control surfaces, missile base flows, nozzles, and rotating machinery. These interactions are often associated with severe boundary layer separation, which is highly unsteady, and exhibits high fluctuating pressure and heat loads. The unsteady motions are characterized by a wide range of frequencies, including low-frequency motions that are about two orders of magnitude lower than the integral-scale fluctuations in the upstream boundary layer. The low-frequency motions are particularly problematic for aircraft structures as they can excite high-amplitude vibration of thin panels, which can lead to fatigue and failure. In this seminar, we will discuss experimental research on various types of shock wave / boundary layer interactions that we have conducted over the past 20 years. The discussion will focus on the use of high-speed PIV and pressure sensitive paint to investigate the physical mechanisms that drive the separated flow unsteadiness in 2D and 3D interactions.