Measurements of the Evolution of Scalar Disturbance Spectra and Heat Transfer Rates on a Flared Cone at Mach 6

A 91-6 flared cone model has been tested in a blowdown Mach 6 wind tunnel. The FLDI optical diagnostic was used to probe the boundary layer on the model and study density fluctuations. The second-mode instability and its harmonics were observed in spectral data and studied in a transitioning boundary layer. IR thermography was used to measure the heat transfer rates at various Reynolds numbers. The heat transfer data were compared to FLDI measurements in the transitional region to better understand how transitional features in heat transfer data compare with the off-body spectral information from the FLDI measurements. Furthermore, any potential link between the turbulent and second-mode wavepacket amplitudes obtained from FLDI measurements band-pass filtered at specific frequencies and the heat transfer observations on the model are being explored.