Flow field generated by a plasma actuator at different elevations in quiescent air

Motivated by the need for improving the lift of unmanned aerial vehicle and replacing the trailing-edge flap under high-altitude environment, the electrical and the flow characteristics of an asymmetrical plasma actuator for a range of elevations [0.2 km ≤ E (elevations) ≤ 4 km] in quiescent air were studied in the present work. In general, compared with the plasma actuator under normal environment, the disturbance capability of the plasma actuator can be enhanced in high-elevation environments and more beneficial to flow control. Initially, the average total power consumption and the maximum amplitude of the induced current increase monotonously with the elevation. Meanwhile, the maximum velocity, Vmax, of the wall jet created by the plasma actuator increases with increasing the elevation and Vmax (velocity) ∼ E0.36. The velocity profile becomes irregular at E ≥ 2 km. Moreover, the relationship between the electrical and the flow characteristics of the plasma actuator is revealed based on the body force and the power consumption. In addition, compared with the case of normal condition, the starting vortex travels further from the upper electrode and the traveling angle is lower at higher elevation, which is benefit for momentum transfer and mixing. It is of great importance that a series of coherent structures in the vicinity of the wall surface were first observed at higher elevation, which is quite different from the case with normal condition.