Review of Flight and Wind-Tunnel Measurements of Boundary-Layer Pressure Fluctuations

Abstract

A review is presented of available data on boundary-layer pressure fluctuations from flight and wind-tunnel investigations. The wind-tunnel data include flatplate pressure-fluctuation spectra and space-time correlations. The flight data include pressure-fluctuation spectra and “equivalent acoustic spectra,” the acoustic fields that would produce the same response as the aerodynamic fields. General trends are indicated by the results, and good agreement is found between flight and wind-tunnel measurements. Of particular interest is the fact that wind-tunnel measurements show the same scatter as flight measurements, in spite of the fact that wind-tunnel flow conditions are much better controlled and boundary-layer parameters are generally measured rather than estimated. For intercomparison purposes, the same normalization procedure has been used with all of the data. This has required the development of engineering curves by which boundary-layer parameters may be estimated. [Work sponsored by NASA-Langley.]