Momentum Transfer for an Aerodynamic Plasma Actuator with an Imposed Boundary Layer

Abstract

In previous work at the United States Air Force Academy, the phenomenology and behavior of the aerodynamic plasma actuator (a dielectric barrier discharge (DBD)) has been investigated. In order to provide additional insight into the phenomenology associated with the transfer of momentum to air by a plasma flow actuator, the velocity distributions upstream and downstream of a plasma actuator with an induced boundary layer were measured using freestream velocities of approximately 4.6 and 6.8 m/s for a range of frequencies (5-20 kHz) and voltages (7.5-10 kV amplitude). The body forces on the air were calculated using a control volume momentum balance. The results show that the body force acts in the sub-boundary layer region. For constant voltage, the body force is proportional to frequency producing a constant impulse per cycle, and the energy dissipation per cycle and efficiency are independent of frequency. The body forces are not affected by the freestream velocity.