Parametric study on far-field sound pressure radiation from an infinite FFS cylindrical shell

The far field sound radiation spectra of an infinite FFS(fluid-filled/submerged) cylindrical shell was studied when a simply harmonic point force applied on it. The formulae of the radial velocity of an infinite FFS cylindrical shell under the concentrated excitation in wave number domain were developed by using wave number domain approach (WDA). Then, the analytical expressions were derived for the far-field sound pressure radiating from the cylindrical shell by using Boundary Integral Equation(BIE). Here, the fluid is non-viscous, isotropic and irrotational coaxial flow. Based on it, the influences of parameters such as kinds of fluid, structural damping, direction of the force on the far field pressure were also investigated. It was shown that the pressure and the resonance frequency would increase with the fluid velocity increasing for downstream propagation. Furthermore, the motion of the light fluid, such as air, has little effect on the far field sound radiation spectrum. Increasing the structural damping is a useful method to control the sound radiation. This paper gives some guidelines on the optimized design of the agricultural mechanism for noise reduction.