MODELING VIBRO-ACOUSTICS OF A STRAIGHT IMPELLER UNDER EXCITATION

摘要

Vibration-induced noise is an important measure of noise abatement for turbo-machinery with different scales. The blade is typically represented as to be the main component to study the vibro-acoustics. In this paper, a typical plastic plate, excited at tip and fixed at hub, is designed for research on noise radiation by vibration. The physical model is developed as well as the mathematical model with coupling between FEM structural dynamics and BEM acoustic prediction. The natural frequency and associated eigenvalue and displacement are calculated as input for acoustic prediction. The sound pressure field along plane of plate and the spherical surface is presented to demonstrate that there exists strong directivity for the sound produced by vibration along span wise. At the near-field, sound pressure field is influenced by vibration plate and exhibits a square-type distribution, while at far-field, the spherical surface is found and the pressure is gradually decreased with the distance increases. In principle, the aim for this study is to investigate the vibro-acoustics for multiple plate fixed on cylinder with rotation. The effects of the variable phase angle between different plate, rotating speed, excitation harmonic frequency and amplitude will be further studied and the results will be more valuable in understanding the mechanisms of vibro-acoustics. And this work will be done in the future.