Plasma synthetic jet actuators as a means of improving the performance of turbofan acoustic liners.

Abstract

A turbofan engine acoustic liner is effective at reducing propagated noise. However, there is room for improving performance or making the liner more compact. Plasma actuators have been shown to be useful flow control devices in a number of fluid flow situations. Combining the plasma actuator (PSJA) and passive liner technologies offers the promise that the attenuation of the acoustic liner can be improved with the addition of the active actuators. The research was divided into two realms: oscillatory flow and bias flow induced by the plasma actuator. A waveguide was constructed with a disturbance speaker at one end, an anechoic termination at the other end, and a mounting for Helmholtz resonators (HRs) in the middle. The PSJA technology was integrated into the neck of the a single HR. A single frequency, feed forward test was conducted to evaluate the oscillatory flow. This test showed that the implementation of the PSJA with a feed forward system could produce an additional 3 dB of attenuation. For this test arrangement the bias flow did not show any additional measurable attenuation. Interpretation of the results are discussed.