Finite Element Study of the Vibroacoustic Response of a Structure, Excited by a Turbulent Boundary Layer

The vibration and the acoustic field generated by a structure submerged in fluid, under a turbulent boundarylayer flow is investigated. This investigation aims at improving numerical models predicting the radiated noise.The studied structure is a plate over a cavity, clamped on the leading edge and with other edges free.The apparatus is immerged in an hydrodynamic tunnel, a turbulent flow is generated on it's upper side andthe cavity is filled with fluid at rest. The vibroacoustic behaviour is mesured with a laser doppler scanningvibrometer and an acoustic transducer in the cavity.Experimental results are compared to a finite element modelization. Modal behaviour of the FSI problemis described through a modal analysis based on the (U,p,&_phi;) formulation with CODE_ASTER. The pressurefield is computed as a sum of plane waves and harmonical analysis are performed for each term of the sum.Spectrum models are used to include the spatial correlation in the sum.The validity of the model is assed by comparing numerical and experimental data for different spectrummodels. A good reproduction of the behaviour of the plate is obtained in terms of defflection shapes andspectral levels.