Jinshuo Zhu
Sean F. Wu
Dept. of Mech. Eng., Wayne State Univ., Detroit, MI 48202
Asymptotic formulations are derived to estimate the dynamic response of a fluid-loaded infinite plate subject to a line force excitation in mean flow. Analysis shows that mean flow may have significant effects on the plate flexural waves when the excitation frequency is above the plate coincidence frequency, moderate effects around the coincidence frequency, and little effects below the coincidence frequency. This is because at high frequencies, most of plate vibration energy is converted to acoustic energy. Since mean flow can greatly modify the radiated acoustic pressure, the effect of mean flow on plate flexural vibration becomes obvious. At low frequencies, there is no sound radiation and most of plate vibration energy stays close to the surface. Consequently, the effect of mean flow on plate vibration is greatly reduced. The asymptotic behaviors of the branch cut integrals at large distances from the point of excitation are also investigated. It is shown that the leading terms of the branch cut integrals decay with distances along the plate surface. The presence of mean flow suppresses the amplitude of the disturbance propagating in the upstream direction, but enhances that of the disturbance propagating in the downstream direction. [Work supported by ONR.]