On the sound produced by a synthetic jet device

Abstract

Synthetic jet is a quasi-steady jet of fluid generated by oscillating pressure drop across an orifice, produced by a piston-like actuator. A unique advantage of the synthetic jet is that it is able to transfer linear momentum without requiring an external fluid source, and has therefore attracted much research within the past decade. Principal applications include aerodynamic flow boundary-layer separation control, heat transfer enhancement, mixing enhancement, and flow-generated sound minimization.

In this thesis, the method of deriving the volume flux equation for a duct is first reviewed, combined with this method, a simplified synthetic jet model is presented, based on the principles of aerodynamic sound, the pressure fluctuation in the acoustic far field is predicted. This model is then been used to predict the minimum synthetic jet cavity resonance frequency, acoustic power, acoustic efficiency, root-mean-square jet speed, acoustic spectrum and their dependence on the following independent parameters: the duct length and radius, the aperture radius, the piston vibration frequency, and the maximum piston velocity.