VIBRATIONS INDUCED BY TURBULENT AIR FLOW EXCITA- TION IN A RECTANGULAR DUCT

Gas transport ductworks in industrial plants or air conditioning networks can be the subject of vibrations induced by the internal flow. Up to date, most studies on this matter have been carried out on circular ducts. This paper focuses on the vibratory response of a rectangular duct under an internal turbulent flow excitation on the basis of a modal analytical approach. The rectangular duct is modeled as an assembly of 4 coupled plates which are simply supported at each end. The excitation is a turbulent boundary layer whose aerodynamic component is modeled by the Corcos model. The impact of higher propagating modes to the duct response is also taken into account as the acoustic component. The related power spectral density of the wall fluctuating pressure field is determined experimentally. The global response of the structure is then quantified by the quadratic acceleration of the whole duct. Finally, comparisons between theoretical and experimental results are given for a 0.2×0.1×0.5 m3 duct made with 3 mm steel plates. Measurements have been performed in our laboratory and experimental results are shown for a flow speed of 30 m/s. As a result, a good correlation is observed between simulation and measurements.