Effect of In-Plane Forces on Sound Radiation From Convected, Fluid Loaded Plates

The purpose of this work is to study the effects that plane stress has on the acoustic radiation from structures subjected to convected fluid loading. It is well established that fluid flow can have significant effects on structural acoustic behavior, along with the fact that induced coupling between discrete modes of vibration becomes significant as flow velocity increases. Work in this area has been confined to flows in air, over unloaded structures, with the effects on sound radiation efficiency, kinetic energy, and sound power radiation quantified and compared for various flow speeds. Theoretical development of the equations governing the vibration of a simply-supported plate subjected to in-plane forces in an infinite baffle and a semi-infinite flowing medium is presented along with a method for coupling these systems. Computational results are presented illustrating the effect of coupling on the sound power radiated from the plate in both subsonic and supersonic flows, for a variety of stress loading cases. It is shown that the state of stress in the plate affects the radiation efficiency of the plate, and that increasing stress eliminates a frequency shift in radiated sound power shown to exist for both subsonic and supersonic flow in previous work.