Parametric investigation of turbulent mixing layer control using Ns-DBD plasma actuators

The effects of ns-DBD plasma actuation parameters on control of a low speed turbulent mixing layer are studied. Parameters include carrier/burst frequency, pulse energy and duty cycle. Focus is placed on both the downstream behavior as well as near the actuator location at the splitter plate trailing edge. In past work, plasma actuators have been used to excite the formation of large scale structures brought on by the Kelvin-Helmholtz instability. This effect was observed for many conventional actuators and for the ns-DBD more recently under high burst frequency forcing conditions. However, the importance of various ns-DBD plasma actuation parameters is still unclear. In the current work, these parameters are examined with emphasis on the near-trailing edge region to shed light on the control mechanisms. Control authority is found to increase with carrier frequency, but a reduction in efficacy is observed for high pulse energy. During successful actuation, a momentum deficit is found in the streamwise velocity near the trailing edge relative to the baseline. This occurs during the actuation cycle causing velocity fluctuations that lead to the formation of large scale structures. The results indicate that a thermal bump or jet-like obstruction is caused by ns-DBD plasma actuators near the splitter plate trailing edge.