AIAA-2005-565-450Acoustic Testing of the dielectric barrier

推进器的声波特性

43rd AIAA Aerospace Sciences Meeting and Exhibit 10 - 13 January 2005, Reno, NevadaAIAA 2005-565Acoustic testing of the dielectric barrier discharge (DBD) plasma actuatorCorrie Baird * University of Colorado at Colorado Springs, Colorado Springs, Colorado 80918 C. L. Enloe and Thomas E. McLaughlin U.S. Air Force Academy, Colorado Springs, Colorado 80840 and James W. Baughn§ University of California, Davis, California 95616 The dielectric barrier discharge (DBD) plasma actuator has been shown to be effective for flow control. Much remains unanswered, however, as to how the actuator couples momentum into air. A better understanding of the coupling mechanism is crucial to determining the performance limitation of the actuator and the breadth of applications to which it can be applied. The small physical volume and transient nature of the actuator plasma make it difficult to make direct measurements. In previous work we have investigated the plasma actuator’s optical emission signature extensively. In this work, we measure and analyze the acoustic emissions, both directional characteristics and waveform, from an actuator in an attempt to shed light on the coupling process. Two sets of measurements were made, each using a different apparatus. Both sets of tests reveal that the actuator adds a larger amount of momentum into the air during the negative-going half of the AC voltage cycle and a smaller amount on the other half of the cycle. It was observed that the acoustic pattern produced is a radiation pattern characteristic of a coherentlydriven system. The results suggest that compressibility effects may play a role in the momentum coupling.I.IntroductionThe dielectric barrier discharge (DBD) plasma actuator has a wide range of demonstrated aerodynamic uses. The DBD plasma actuator has already been shown to reduce and in some cases eliminate the separation bubbles on turbine blades1-2. It has also been shown to be effective in reattaching separated flows at high angles of attack on thin airfoils3-5, providing velocity increments near aerodynamic surfaces in low speed flows to delay separation6-10 and stall11, and to control the phase of vortex shedding from a circular cylinder12. Further investigations of the spatial and temporal aspects have led to an analytical model to describe plasma behavior by Enloe et. al.13-14 However, there is still much unknown about how the actuator couples momentum into air. A better understanding of this interaction will lead to its optimization. This paper attempts to gain insight into the coupling of momentum into air through the actuator’s directional acoustic signature and waveform.This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States.* Graduate Research Assistant, Mechanical Engineering, Student Member AIAA. Professor, Department of Physics. Senior Member AIAA Director, Aeronautics Research Center, Department of Aeronautics, Associate Fellow AIAA § Professor, Department of Mechanical and Aeronautical Engineering, Member AIAA 1 American Institute of Aeronautics and AstronauticsThis material is declared a work of the U.S. Government and is not subject to copyright protection in the United States.