Shock wave/turbulent boundary layer interactions and control of shock-induced separation

Time: Thu 2019-05-23 10.30 - 11.30

Lecturer: Anne-Marie Schreyer (RWTH Aachen)

Location: Faxén, Teknikringen 8

Abstract: Shock-induced flow separation strongly influences the aerodynamic behavior of many aerospace applications, from transonic airfoils and supersonic air-breathing propulsion, to control surfaces on hypersonic vehicles. The associated highly unsteady flow field can cause inlet instability, severe local thermal loads, as well as buffeting and structural fatigue when pressure oscillations excite a resonant frequency. The importance of these flows in aerospace transportation motivated great efforts to understand the governing mechanisms in the flow and to develop methods that reduce the detrimental effects of separation. Micro vortex generators, either as robust and simple mechanical devices or as versatile air-jet vortex generators (AJVGs), have drawn recent attention. These devices introduce longitudinal vortex pairs into the boundary layer. The vortices entrain high-momentum fluid and increase turbulent mixing, which leads to smaller separation zones and a reduction of the associated unsteadiness. Micro vortex generators have many advantages: unlike with boundary-layer bleed, internal mass-flow rates in engines are not reduced and the parasitic drag is decreased compared with larger devices. AJVGs can even be turned off when not needed. Better understanding of these flows and control methods will thus contribute to preparing the ground for new exciting aerospace transportation concepts and affordable access to space.