Aerodynamics

Shock-Boundary-Layer Interactions

In supersonic flow whenever a shock and a boundary layer meet, they interact with each other. These so-called shock boundary-layer interactions can be found for example in jet engine inlets, compressors, rocket nozzles or trans- and supersonic wings.

The positive pressure gradient imposed by the shock thickens the local boundary layer and for a sufficiently strong shock it can even separate. This causes a very complex and unsteady flow field with a high bandwidth of frequencies. The motion of the reflected shock is particularly interesting because it oscillates at a relatively low frequency but with a high amplitude that can cause temperature spikes, panel flutter and even catastrophic damage to vehicles. The mechanism behind this motion is to this day not very well understood and thus makes designing supersonic vehicles quite challenging.

At the chair of Aerodynamics we contribute to the research in this field by using state of the art measurement technologies such as high-speed Schlieren/PIV and novel Piezo Foil Sensors that can measure pressure fluctuations at a high spatial and temporal resolution to analyze the low frequency unsteadiness. We investigate different configurations by altering the shock strength and boundary layer condition (Laminar/turbulent) and explore the effect of flow control on the interaction behavior.