Study on electroaerodynamic characteristics of helium plasma jet under repetitive nanosecond pulsed discharge excitation

This paper explores the aerodynamic characteristics of the He plasma jet under nanosecond pulse needle-ring discharge excitation (dielectric-barrier), and the influence of typical pulse parameters on the flow field is preliminarily ascertained. Schlieren photography is employed to visualize the flow field of the jet, and dynamic processes from plasma generation to post-discharge evolution are recorded in detail by a high-speed camera. The visualized images reveal a transition from a laminar to a turbulent region in the flow field outside the tube following discharge excitation. The turning point (turbulent vortex) propagates at a speed of m s⁻¹. The results show that a higher driving voltage leads to an earlier onset of the turbulent vortex and further shortens the laminar zone length, with a maximum reduction of 36%. The turbulent vortex dynamics gradually diminish as the frequency increases, resulting in a maximum 30% reduction in the laminar zone length after the cumulative effect of several cycles. Also, the impact of the pulse width parameter on the flow field is minimal. By observing the changes in the distribution of gas temperature under different discharge parameters, it is concluded that the thermal effect is the main factor influencing the kinetic process of the flow field.