Vibroacoustic analysis of a fluid-loaded cylindrical shell excited by a rotating load

A modal analysis study is presented to evaluate the vibroacoustic behaviour of a cylindrical thin elastic shell of finite length, extended by two semi-infinite perfectly reflecting cylinders. The shell is immersed in a stationary and non-viscous fluid extending up to infinity, and excited by a constant point load travelling continuously along the circumferential direction at a rotating speed Q. An expression of modal displacement amplitude of the submerged shell is given, which shows that the shell is exclusively excited only when the circumferential mode order n equals the harmonic order N of the rotating load. For this rotating excitation, the vibration and radiation critical speeds are identified. Extensive numerical results are also presented to illustrate the comparison of vibration and sound radiation ability in two different fluids, which show that the behaviour of the shell in water is very different from that of the one in air.