Use of turbulent model to calculate the vibration and radiation responses of a panel, with practical suggestions for reducing sound level

Abstract The problem of acoustic radiation of panels excited by random pressure fluctuation of the turbulent boundary layer has been further investigated. In the past, experimental investigators have concentrated only on certain phases of the general problem; for example, the statistical behavior of the pressure field (Willmarth and Wooldridge, [1]) or the motion of the panel (el Baroudi, [15]). Recently the author presented a comprehensive set of experimental results [4, 5] that includes the most pertinent statistical information concerning the forcing function (pressure fluctuation) and the response functions of the panel motion, as well as the radiation field. An even more recent consideration has been of a model that contained fluctuation on the convection velocity itself. The main purpose of this paper is to show, by a relatively simple function representation of the space-time correlation of the wall pressure fluctuation incorporated in the Lyons-Dyer method [22], that the motion and radiation intensity of a simply supported panel agree reasonably well with the experiment when edge restraints and damping are taken into account. The most striking feature of the excitation mechanism is the so-called coincidence, which has profound effects on the response of the structure and power radiations. If, under certain conditions, a mismatch occurs between wave speeds on the panel and the pressure field, panel displacement and acoustic radiation are reduced. Such a mismatch is caused by a turbulence pressure eddy that normally decays faster than the mode's wavelength on the structure. Remarkable changes in power level have been obtained by varying the edge conditions of the panel boundaries. Practical ways of minimizing the acoustic power radiation are demonstrated.