Linear arrays of powered resonance tube actuators for aeroacoustic control

Abstract

Experiments were conducted to characterize the performance of a linear array of powered resonance tube actuators developed jointly by Boeing and IIT. The actuator is an adaptation of the Hartmann whistle and devices of this type have been shown to be effective in suppressing flow generated acoustic tones that commonly occur in aircraft applications, such as impingement tones and cavity resonances (Raman et al., AIAA Paper 2000-1930; Stanek et al., AIAA Paper 2000-1905). The goal of this characterization is to provide a database that can be used to compare the performance of these actuators with other actuator designs (such as piezoelectric actuators) and to optimize the design of these actuators. Optimization involves modifying the geometric parameters of the actuator in order to get the maximum acoustic control with minimum input mass flow rate. In order to accomplish these tasks, detailed measurements of the fluctuating velocity and pressure were made at numerous locations in the flowfield at the actuator exit. Results indicate that the actuation could produce frequencies ranging from 4352 to 11<th>070 Hz (for the 1/2 inch depth tube chosen). Amplitudes were as high as 156 dB in the vicinity of actuation. [Work supported by Boeing/DARPA.]