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 uRMS′ , 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.