Effect of geometric parameters on the flow field and impulse of three-electrode plasma high-energy synthetic jet actuator

Plasma actuators have been become the research focus in flow control and fluid dynamic fields because of the advantages of simplicity, fast response and robustness. Compared with typical two-electrode actuator, three-electrode Plasma Synthetic Jet Actuator(TE-PSJA) possesses the advantages of higher energy efficiency and bigger jet impulse, and has potential to be adopted as a fast-response direct force generation device. In order to reveal the effects of geometric parameters on the flow field and impulse, discharge characteristic, flow field and impulse of TE-PSJA with different orifices, volumes and electrode gaps were experimentally studied using electric parameter measurement device, high-speed shadowgraphy and single line torsion pendulum system. In order to compared the working characteristics of the actuator in different conditions, dimensionless energy deposition ε and dimensionless jet impulse I^* were defined, and the effects of geometric parameters on ε and I^* were analyzed. Results showed that the best jet orifice diameter is existed, ε and I^* decreases as volumes increase, but increases as electrode gaps increase, strength and affected area of the jet decrease as volumes increase, while increase as electrode gaps increase. A similar flow structure which contains a mushroom-shaped jet and a spherically symmetric precursor shock above the jet front was observed. Compared with the variation of I^* with ε on the different volumes and electrode gaps conditions, it can be concluded that in order to design actuators which possessed better jet impulse level, the dimensionless jet impulse I^* should be increased as possible with the same ε. The cavity volume should be increased so as the dimensionless energy deposition ε is to be the design value when the dimensionless energy deposition is less than the initial case. On the contrary, the electrode gaps should be increased so as the dimensionless energy deposition ε be the design value when the dimensionless energy deposition is larger than the initial case.