湍流边界层激励下加筋平板振声响应特性研究

船舶、汽车和飞机等高速运动时,其外壳受湍流边界层壁面脉动压力激励而产生的内场声辐射成为该类交通工具自噪声的重要成分。基于模态叠加法计算结构振动响应。采用湍流壁面脉动压力功率谱Corcos模型,计算了外侧气流或水流湍流边界层激励下简支平板振动及内场辐射声,计算值与解析解和试验值吻合良好,验证了算法的有效性。采用湍流壁面脉动压力功率谱改进型Corcos模型,研究了外侧水流湍流边界层激励下平板及板格的振声响应特性,结果表明:水流马赫数低,壁面脉动压力迁移波数大于平板结构弯曲波数,壁面脉动压力波数-频率谱的迁移脊对平板的激励作用可以忽略;横向或纵向加筋对板格振动速度自功率谱级基本无影响;减小板格宽度与长度之比,适当增大板格流向长度可使平板振动辐射声功率在2 000 Hz以上明显降低。

Vbration & acoustic response characteristics of a stiffened plate stimulated by turbulent boundary layer wall pressure fluctuation

While transportation vehicles such as ships，auto-mobiles and airplanes travel fast，the inward sound radiated by their outer surface vibration would become a vital part of the self-noise，this kind of vibration is induced by turbulent boundary layer wall pressure fluctuation．Structural vibration responses were calculated based on the modal summation．The Corcos model was used to estimate the power spectra of the turbulent boundary layer wall pressure fluctuation in the calculation of the vibration and inward sound radiation of a simply supported plate stimulated by outer air or water flow turbulent boundary layer.The calculation results fit well with analytical and experimental ones，which proves the validity of the method．Moreover, an improved Corcos model was used to estimate once more the power spectra，and the vibration and inward sound radiation characteristics of the simply supported plate stimulated by outer water flow turbulent boundary layer were investigated．The results indicate that, attributing to the low Mach number of the water flow，the convective wave number of wall fluctuating pressure is far greater than the plate structure flexural wave number，thus the stimulation caused by the convective ridge of the wave number-frequency spectra of wall fluctuating pressure could be neglected.Span-wise or stream-wise stiffeners do little effect on plate velocity auto-spectra.Decreasing the panel aspect ratio and properly increasing the panel stream-wise length would cause evident decrease on the plate radiated sound power above 2 000 Hz．