Flowfield induced by a plasma synthetic jet actuator with low exit inclination angle under low ambient pressure

Abstract

A new plasma synthetic jet actuator with low exit inclination angle is proposed. Transient flow features under an ambient pressure of 13 kPa are experimentally tested. It's found that the plasma-induced flow can be classified into two stages, namely, initial shock diffraction dominated stage and the stratified flow stage. Regarding the shock diffraction dominated stage, a curved primary shock following a rotational jet will be formed; during the latter stage, it's dominated by the buoyancy and inertial effects jointly, leading to an upward and forward moving jet. The initial jet can accelerate to a maximum speed of ∼300 m/s, and the high speed of the jet can maintain for about 60-100 μs with its trajectories during the whole lifetime showing a piecewise linear feature. The repeated working of the actuator is examined as well, and the results demonstrate that the actuator can operate stably with the frequency ranging from 100-2 kHz. Although the increase of operating frequency lowers the moving speed of the primary shock and the jet to some extent, it retards the duration of the high-speed jet. Additionally, the effect of deposited energy per cycle on the flow characteristics of the actuator is studied. As the deposited energy decreases, the primary shock and jet move more slowly. In conclusion, the deposited energy per cycle of 82 mJ and the operating frequency of 1 kHz can induce a relatively high-speed jet with a longer duration.