VORTEX STRUCTURAL POWER-FLOW IN A THIN-PLATE AND THE INFLUENCE ON THEACOUSTIC FIELD

This article examines the characteristics of real vibrational power fl ow in a simply supported rectangular panel under the action of feedfor ward vibration control, induced by a control source input which is sli ghtly suboptimal such that the primary source is producing a slight am ount of real vibrational power, and the control source is absorbing th e same amount. It is found that the path of the power flow is a combin ation of translations and rotations, the rotations induced by the inte rference of two modes which produces a ''vortex generating block.'' A qualitative formula for predicting the number of power flow vortices, as well as the discussion of the vortex period, is put forward. A nove l method to induce a vortex at an arbitrary location of the plate is a lso shown, which may have practical applications in controlling the pa th of vibrational power flow in systems of large extent. Moreover, the influence of the induced vortex power flow on the plate onto the acou stic intensity distribution is investigated, showing that the rotation al direction of the vortex on the plate is not always the same with th at of the acoustic intensity in the near field.