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A MODEL FOR THE VIBRO-ACOUSTIC RESPONSE OF PLATES EXCITED BY COMPLEX FLOWS

✍ Scribed by F. HAN; L.G. MONGEAU; R.J. BERNHARD


Publisher
Elsevier Science
Year
2001
Tongue
English
Weight
598 KB
Volume
246
Category
Article
ISSN
0022-460X

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✦ Synopsis


A model was developed and applied for predicting the vibration response of structures excited by complex vortical turbulent #ows. Computational #uid dynamic (CFD) methods were utilized to model the #ow over the structure. The computations allowed the general #ow patterns to be identi"ed and the mean properties of the #ow "eld to be calculated. The spectral characteristics of the dynamic wall pressure #uctuations were obtained from an empirical database developed from genetically similar #ows. The Corcos model was used to characterize the dynamic surface pressure cross-spectra. The power input into the structure was estimated accounting for the non-uniform dynamic pressure loading on the structure. The energy #ow analysis (EFA) method was then used to predict the high-frequency structural vibration response and the radiated sound power. The frequency limit of the accuracy of the model was established. The model was applied to the case of a clamped rectangular homogeneous panel excited by vortical #ows. The model predictions were veri"ed experimentally for the case of an aluminium panel installed in a low-speed wind tunnel downstream of three-dimensional vortex generators. The wall pressure #uctuations, the plate transverse vibration velocity, and the acoustic pressure radiated from the plate were measured over a range of mean #ow velocities. The measured surface pressure spectra beneath the coherent #ow structures formed behind the vortex generators were found to be similar to those behind uniform fences at high frequencies. This con"rmed that high-frequency wall pressure #uctuations depend on "ne grain turbulence rather than on the large-scale #ow structures. The measured panel vibration responses, and the radiated acoustic pressure levels were found to agree well with model predictions at frequencies above the model predictability threshold. The proposed modelling approach o!ers the opportunity to develop tools that could assist the vibro-acoustic design of complex #ow-excited systems such as vehicles, or #uid machinery.


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