Numerical study of volute casing vibro-acoustics in a marine centrifugal fan

A numerical parametric optimization of a vibro-acoustic coupling method that considered the influence of vibro-acoustic coupling was carried out to investigate the casing vibrations and feathers of vibrational noise induced by unsteady flow of the marine centrifugal fan at the best-efficiency point (BEP). There are three important aspects of this method. First, an unsteady flow-field with a whole impeller-volute configuration was solved to obtain the source of the vibro-acoustics. Second, a fluid-structure-acoustic coupled method was implemented to study the volute vibrations and behaviours of vibrational noise. Besides, the generation mechanism of vibrational noise of the volute casing was also revealed. Moreover, the positions of the noise source of the volute casing was studied and revealed applying the panel acoustic contribution analysis (PACA) method. Third, the panel thicknesses of the volute casing (such as front-panel thickness [FT], side-panel thickness [ST], and back-panel thickness [BT]) were defined as design variables, and the outlet acoustical power of the volute casing surface was also defined as an optimal target function. Then, the parametric analysis method was used to explore the parametric relationship between the two. Fan aerodynamic performance, volute casing surface fluctuations, and vibrations were validated by experiments, and showed good agreement. The parametric analysis provides a reasonable range of values of three panel thicknesses that result in minimal vibrational sound radiation.