Enhancement of synthetic jets by means of an integrated valve-less pump

This study presents a new fluid jet actuator based on a novel principle of generating of a fluid jet. The fluid jet actuator consists of a synthetic jet actuator and a valve-less pump. The resulting periodical fluid jet has an intrinsically non-zero-net-mass-flux, in contrast to a synthetic jet actuator. The actuator operates in a double-acting regime; both up- and down-strokes of the diaphragm force the fluid to flow out from the central and annular nozzles, respectively. The optimal operating parameters of the actuator have been determined from both a simplified theoretical analysis and experimentation. The diaphragm displacement, time-mean reaction force, and time-mean flow velocities have been measured. A comparison between actuations by sine and square waves has shown that the sine-wave excitation of the diaphragm is more effective.