2列マイクロフォンアレイを用いた乱流境界層における壁面圧力勾配変動の測定

Abstract

It is known that wall pressure fluctuations in a turbulent boundary layer are closely related to the turbulent flow structures. In this study, a two-rows 60ch microphone array has been developed to evaluate the wall pressure fluctuations and its spatial gradients. The measurements have been conducted in a turbulent boundary layer. The probability density functions (PDFs) of the wall pressure fluctuations exhibit intermittent characteristics and clear departure from the Gaussian distribution. In the PDFs of the wall pressure fluctuation gradient, the spanwise gradient indicates the symmetric profile as it is expected from the geometrical symmetry of the flow. On the other hand, although the streamwise gradient is considered to show the negative skewness because of the effect of the mean velocity gradient on the fluctuations of the spanwise vorticity flux, the PDFs of the present data show rather symmetric distributions.