Parametric study of Ns-DBD plasma actuators in a turbulent mixing layer

Excitation of a low-speed turbulent mixing layer using nanosecond dielectric barrier discharge (ns-DBD) plasma actuators is demonstrated here under various forcing conditions. The mixing layer behavior downstream is examined in the context of observations near the point of actuation (splitter plate trailing edge). Parameters explored include carrier/burst frequency, pulse energy, and duty cycle. Control authority is found to increase with carrier frequency, but a reduction in efficacy is observed for high pulse energy and lower duty cycle. During actuation, a streamwise velocity deficit is found near the trailing edge relative to the baseline. This causes velocity fluctuations that are amplified and lead to the formation of large-scale structures. The results indicate ns-DBD plasma actuators in burst mode acts as an obstruction giving rise to cross-stream perturbations that cause mixing layer growth. Graphic abstract