Investigation of flow separation control by nanosecond pulsed dielectric barrier discharge actuators

Abstract

The ability of nanosecond pulsed dielectric barrier discharge (DBD) actuators to control §ow separation was investigated on a NACA (National Advisory Committee for Aeronautics) 0015 pro¦le for velocities up to 24 m/s (Re = 230,000). The optimal location for the actuator was determined from oil §ow experiments. Moderate voltage levels were applied (3 and 6 kV) and the actuator was operated at frequencies ranging from 0.058 to 10 kHz in pulse and burst modes. The peak e¨ectiveness of the actuator occurred at reduced frequency values of around 1. Plasma in §uence was observed at all tested angles of attack (up to 26 • ) and the stall angle was delayed by 8 • .

Mechanisms of Control Authority by Nanosecond Pulsed Dielectric Barrier Discharge Actuators on Flow Separation

“…Two values of voltage were used to produce plasma, specifically 4 kV and 7 kV, in order to study the effects of applied voltage on the control authority of the DBD. This gave interesting results, and what could at first be considered as contradictory data, which also confirmed observations made by Grech et al [22]. Repeatability problems are not inferred.…”

“…The excitation of these structures induces efficient entrainment of the flow and induces the most effective flow attachment. If the discharge power is not sufficiently large to effectively excite the shear layer, only the first mechanism remains [15,17,[19][20][21][22]. These shedding structures have been observed also in PIV measurements for relatively low-speed flow (up to 60 m/s) in a study by Little et al [19].…”

“…As the occurrence of plasma on an airfoil surface induces only a relatively small effect on the airflow, it is clear that, to gain any significant advantage from its use, considerable leverage should be provided by the flow sensitivity. Many experimental studies [15,[20][21][22] have been performed with the aim of determining the optimal location of a NS-DBD actuator on such a profile. These studies have consistently shown that the maximum effect is achieved when the electrodes are positioned such that the discharge zone is located just upstream of the separation point.…”

Understanding SDBD Actuators: An Experimental Study on Plasma Characteristics

“…5,6 For these actuators, the working mechanism is believed to be the generation of compression waves that emerge from the surface, adding pulsed energy to the flow. Little et al 7 and Grech et al 8 have investigated the application of ns-DBD actuators to delay separation for lower flow velocities, up to u ∞ =62 m/s, where the generated compression wave acts as an active trip at pre-stall angles of attack. The plasma produced here is essentially a streamer discharge regime propagating along the surface of the dielectric.…”