Wall pressure fluctuations and radiated sound from turbulent boundary layer on flat plate and axi-symmetric body

초록

The wall pressure fluctuations of a turbulent boundary layer over a flat plate and axi-symmetric bodies have been investigated in an anechoic wind tunnel facility. To improve spectra characteristics in a high frequency range, a 1/8" pressure-type microphone sensor, which has a pin-holed cap of various diameters, was employed in this experiments. The measured wall pressure spectra for the flat plate in terms of three types of scaling parameters were in good agreement with other experimental and numerical results. The axi-symmetric bodies considered in this study gave the hemispherical or ellipsoidal noses on which the near-field pressure fluctuations were investigated in a laminar separation region, a turbulent shear layer, and a fully developed turbulent boundary at a Reynolds number of . While the significant increases of energy level especially in the low frequency region can be noticed downstream of the laminar separations on all nose models among three regions, the region positive events are most dominant in the turbulent shear layer region. The dipole sounds from the laminar separation zone were found to radiate to a far-field effectively. The characteristics of the turbulent boundary layer and wall pressure fluctuations were also measured in an axial cylinder flow at and and reported in this study.