Measurements of Turbulent Boundary Layer Wall Pressures

초록

We examine the problem in which viscoelastic compliant thin plates are subject to pressure fluctuations under transitional or turbulent boundary layer. Measurements are presented of the frequency spectra of the near-field pressure and radiated sound by compliant surface. A visco-elastically-painted plate of 1mm thick over an acoustic board of 4mm thick were placed over a rigid surface in an anechoic wind tunnel. The wall pressure autospectra and streamwise wavenumber-frequency spectra were non- dimensionalized and compared to see the attenuation effects of compliant coatings. Streamwise velocity and wall pressure measurements showed that compliant-coated wall highly attenuated the convective wall pressure energy when the convective wavenumber (kch) was 3.0 or more. The sound source localization on the compliant walls was applied to the measurement of radiated sound by using an acoustic mirror system.