난류유동장 내에 놓인 탄성을 갖는 박판의 방사소음에 대한 실험적 연구

초록

The structural modes driven by the low-wavenumber components of smooth elastic wall pressure provide a relatively weak coupling between the flow and the wall motions. If the elastic thin plate has any resonant mode whose wavenumber of resonance coincides with ω/Uc, the power will be transmitted to those modes of vibration by the flows. We examine the problem in which the elastic thin plate is subject to pressure fluctuations under turbulent boundary layer. Measurements are presented of the frequency spectra of the near- and far-field pressures contributed by the various wave modes. Their dependence on elastic properties of thin plate is discussed, e.g. mass density of thin plate and tension applied to the plate. Dispersion equation for wave motions of elastic plate was used to investigate the effect of bending waves of relatively low wave numbers on radiated sound. Also the contribution of scattering noise among lots of sources on elastic thin plate is analyzed by using acoustic mirror system.