Design and testing of an acoustic-to-flow energy conversion device*

A unique concept for the direct conversion of acoustic energy to kinetic energy in a boundary layer was developed and demonstrated. The device used a cavity with the upper surface constructed from a stretched membrane that was exposed to an incident sound field. A pitched orifice was located downstream of the membrane, which functioned as a synthetic jet. The membrane was acoustically excited in order to energize the periodic jet flow. A 2-degree-of-freedom design calculation was used to predict the natural frequencies of the device. Hot-wire measurements in an anechoic wind tunnel facility indicated a significant increase in mean and RMS velocity in the region downstream of the orifice when the device was exposed to an incident tonal acoustic pressure. The device has potential application as an aircraft engine acoustic liner that can improve internal aerodynamic performance.