Non-intrusive generation of instability waves in a planar hypersonic boundary layer

The aim of this work is to show the possibility of non-intrusively exciting second-mode instability waves with arbitrary frequency and amplitude in a hypersonic, planar boundary layer, by means of optical methods. Surface heat flux sensors were used to measure natural and artificially excited instability waves on a flat plate at zero angle of attack. The measurements were made using a stream-wise array of flush-mounted high-frequency heat flux sensors. In addition, surface pressure sensors were applied and show the instability waves, as well. The possibility to generate such waves by locally heating the model surface is shown.