Experimental Characterization of a Pulsed Plasma Jet

摘要

The characteristics of a pulsed plasmajet exhausting into quiescent air under a single-pulse operation are presented. A HV trigger of approximately 3.6 kV was used to ionize the air gap between an anode and a cathode. The subsequent electric arc discharge deposits energy from a capacitor charged to a voltage near 570 V. Three capacitor sizes were examined: 0.25, 2, and 25 μF with calculated energy additions of 41 mJ, 330 mJ, and 4.0 J, respectively. Schlieren images and particle image velocimetry measurements revealed that the jet structure, local velocity, penetration depth, and exhaust duration are strongly dependent on capacitance, and thus energy deposition. Peak velocities were measured to be 130, 320, and 496 m/s for the three capacitances tested. A pulsating jet behavior was observed for each capacitor case and is reasoned to be the result of cavity wave dynamics. Modifications to the actuator geometry, including the cavity volume and orifice diameter, and the capacitor-charging power supply are necessary for high-frequency activation required for many flow-control applications. However, owing to the ability to produce coherent ring vortices and significant jet velocities far from the orifice exit, the pulsed plasmjet actuator shows promise as an active flow-control device for influencing and controlling supersonic flows.