Development of a high bandwidth Hartmann–Whistle type actuator

Abstract

There is current interest in using Hartmann–Whistle type powered resonance tube actuators for aeroacoustic control. Previous experiments (Raman et al. (2000, 2001) AIAA 2000-1930; Stanek et al. (2000) AIAA 2000-1905) have shown that such actuators with no moving parts are very effective in the suppression of flow impingement and cavity noise. However, fixed geometry actuators can only produce effective actuation over a small range of frequencies. Our idea is to use a variable depth powered resonance tube actuator where the depth of the resonance tube and the distance between the supply jet and the resonance tube can be controlled actively during the experiment. The experimental setup consists of a 1/4′′ diameter jet facing the open end of the resonance tube that is closed at the other end. The tube depth is changed by a computer controlled piston fitted inside the tube. Microphone and pressure sensors located at various locations in the vicinity of actuation were used to measure the frequency and amplitude of the fluctuations produced by this device. Due to the high amplitudes of pressure within the resonance tube the linear eigenfrequencies do not predict the measured frequencies. [Work supported by AFOSR.]