A COMPARISON OF MODELS FOR THE WAVE-NUMBER-FREQUENCY SPECTRUM OF TURBULENT BOUNDARY-LAYER PRESSURES (REPRINTED FROM PROCEEDINGS OF FIRST CEAS AIAA AEROACOUSTICS CONFERENCE, JUNE, 1995)/

Aircraft cabin noise due to the fuselage boundary layer is determined by, among other factors, the wavenumber-frequency spectrum of the fluc tuating boundary layer pressures, a quantity for which a number of mod els have been proposed. In this work predictions for the sound radiate d by a boundary layer driven plate are investigated, with a view to de termining which model is most appropriate to the cabin noise problem. It is found that, for the structural and boundary layer parameters typ ical of transport aircraft, the contributions of resonant, acousticall y inefficient plate modes dominate the radiated power. When these mode s are strongly driven by the boundary layer, their excitation levers a re determined by the ''convective peak'' of the wavenumber-frequency s pectrum (where most of the fluctuation energy lies), and the radiated sound is found to be sensitive to details of the shape and location of the peak, giving differing results for models normally thought to agr ee at this point. Otherwise, it is the sub-convective region of the wa venumber-frequency spectrum that is important, and differences between models here lead to corresponding discrepancies in radiated sound pre dictions. Since the first case is generally more problematic, one can conclude that a suitable model must above all describe the convective peak accurately; however, the extent to which existing alternatives do so remains unclear. (C) 1997 Academic Press Limited.