Abstract:

The results of numerical experiments associated with examining the potential performance of active blankets attached to the interior of a payload fairing to reduce the interior acoustic levels are presented. These studies are carried out using a finite-element--infinite-element model of the full fluid-structure system. In this model, the main rocket body is modeled as a finite cylinder with an attached rib-stiffened fairing. The interior fluid is modeled with finite acoustic elements while the entire exterior fluid is modeled with finite and infinite acoustic elements. Examined first is the broadband nature of the interior acoustic response due to a high-order acoustic field developed as a result of a point acoustic source located at the base of the rocket and laterally separated by approximately one rocket length. Next, control simulations are performed that impose a specific acoustic impedance at the interface between the structure and the fluid, thus simulating the acoustic boundary control (ABC) approach. Finally, the performance of an acoustic boundary control implementation is examined for several specific acoustic impedances together with some simple antisound configurations. [Work supported by the Office of Naval Research.]