Spectral analysis of phase-shifting measurements of crossflow waves

Computing amplitudes of periodic components in a measured signal is commonly encountered in data analysis. When this process is hampered by low-resolution data, it is sometimes possible to exploit certain qualities of the data to mitigate these limitations. In this work, spectral analysis of crossflow vortices measured in flight tests using multi-element hotfilm sensors is accomplished despite restrictive sensor counts. The vortices are nominally steady but subject to randomly changing phase shifts that can be computed to form well-resolved sets of data. The reliability and efficiency of this analysis are tested via Monte Carlo simulation and the uncertainties in detected wavelengths are quantified. This analysis technique is applied to in-flight measurements of crossflow instabilities in swept-wing boundary layers.