Profiles of streamwise velocity and fluctuations in a hypersonic turbulent boundary layer using acetone tagging velocimetry

Acetone tagging velocimetry (ATV) with nominally 1% mole fraction acetone seeding was conducted in a shock-tunnel-generated hypersonic turbulent boundary layer over a hollow-cylinder-flare at M e = 6.05 , T w / T r = 0.65 , Re θ = 8925 , and Re τ = 408 . This single-laser tagging velocimetry experiment measured streamwise velocity and fluctuations, u ¯ and u RMS ′ , had a repetition rate of 50 kHz, and did not require the use of an image intensifier. The ATV data are non-dimensionalized via the van Driest transformation and compares well with the literature down to y + ≈ 3 ; this is into the viscous sublayer. The Morkovin-scaled fluctuations matched the literature for y + > 10 ; however, below y + ≈ 10 , it appears that the noise introduced by the measurement technique, in addition to the velocity differences being small near the wall, rendered the ATV-measured Morkovin-scaled fluctuations below y + = 10 not useful.