Interior noise field of a viscoelastic cylindrical shell excited by the TBL pressure fluctuations:Ⅰ. production mechanism of the noise
-
摘要: 用波数-频率谱传递函数描述包括粘弹性圆柱壳和流体负荷在内的整个系统,导出了TBL(湍流边界层)压力起伏激励下管内噪声场互谱函数的一般表示式。存在着两种噪声产生机理:一种是压力起伏的迁移峰通过柱壳直接传递,另一种是压力起伏激励桂亮共振产生再辐射。在低频情况下。后一种机理产生的噪声起主要作用。通过求解带有流体负荷的圆柱壳的频散方程,得到复K平面上两个Stoneley型极点。它们是低频条件下管内噪声的主要源。最后,用数值积分方法计算了柱壳半径、壳厚、材料吸收及流速等因素对噪声降低值的影响。Abstract: Applying the wavenumber frequency transfer function to describe the whole system including the elastic cylindrical shell and the fluid loading, a general expression of the cross spectrum of the interior noise induced by the TBL (Turbulent Boundary Layer) pressure fluctuations is derived. There are two production mechanisms of the noise: direct transfer of the convective ridge of the pressure fluctuations through the shell, and reradiation of resonance modes excited by pressure fluctuations. At low frequencies the noise produced by the latter mechanism is dominant. Solving the frequency equation of the cylindrical shell with liquid loading, the two Stoneley-type poles in the complex K plane are presented. They are major sources of the reradiation of shell at low frequencies. Finally, effects of the shell radius, shell thickness, material absorption and flow speeds on the noise reduction are computed by numerical integration.
-
计量
- 文章访问数: 73
- HTML全文浏览量: 3
- PDF下载量: 15
下载:
