Spectral Analysis of Mach 6 Turbulent Boundary Layer over a Hollow Cylinder with FLDI and DNS

In this paper, we present a comparison of experimental measurements of density fluctuations over a hollow cylinder to DNS data at similar conditions and wall-normal positions. The experimental observations are made using a closely-spaced multiple beam-pair FLDI flow diagnostic incorporating a technique to improve the signal-to-noise ratio, thus allowing for data to be captured above 1 MHz. The power spectral density (PSD) and two-point space-time correlations and coherence spectra computed from FLDI and DNS data are compared. The PSD spectra are further compared with expected power-law scalings in specific regions. With few deviations, good agreement is generally observed between the FLDI and DNS results and applicable power-law scalings.