Updating of wavenumber-frequency spectrum models by a phased array measurement

Abstract

This study mainly presents the updating of wavenumber-frequency spectrum models (W-F models) based on spatial correlation measurement by a phased array technique, which is critical for the evaluation of the structural vibration caused by a turbulent boundary layer. Measurements are carried out in a wind tunnel, and the effect of background noise on identifying the spatial correlations of pressure fluctuations is discussed. To improve the resolution of the beam map used to estimate the spatial correlation by the beamforming algorithm, focusing functions are introduced to accelerate beam focusing. Then, broadband fluctuations and flow-speed effects on spatial correlation identification are discussed to estimate the adaption scope of the phased array technique. To update W-F models of wall pressure fluctuations, the subsection approaching method (SAM) is employed to extract the power spectrum of wall pressure fluctuations based on the identified spatial correlation. The investigated results reveal that the spatial correlation of wall pressure fluctuations caused by the turbulent boundary layer obeys a statistical law but does not constitute an exact math expression, which further validates the necessity of the phased array technique in spatial correlation identification.