Synthetic jet actuator using bubbles produced by electric discharge

Abstract

Over the last decade, synthetic jets suitable for micro-machinery have received attention for their potential to replace continuous jets. The development of synthetic jet actuators with, for example, a diaphragm, a piston, a piezoelectric element, or a speaker cone instead of mechanical drivers, is required for the downsizing and weight reduction of flow control systems in fluid machines. In this study, an experimental prototype for a synthetic jet actuator that uses the nonlinear oscillation of bubbles produced by repetitive electric discharge is proposed. Numerical simulations are performed to clarify the fundamental flow behavior of the synthetic jets produced by bubble motion. The behavior of a bubble induced by a single discharge and the estimated change in nozzle exit velocity with time are shown, and typical flow patterns for synthetic jets produced by periodic electric discharge are discussed. The influence of the ratio of the bubble driving cycle period to the electric discharge cycle period (T*) on the unsteady flow pattern and the time-averaged jet structure is investigated in detail. In addition, the flow characteristics of a synthetic jet with downtime are compared with those of a normal synthetic jet produced by linear oscillation under the condition that the strokes of both jets are equivalent.

Keywords

• synthetic jet
• continuous jet
• unsteady flow
• electric discharge
• non-linear oscillation