By means of experimental investigation of the unsteady flow near the orifice of synthetic jet actuator using PIV technology and using the phase-locked sample technique

72 instantaneous images and quantitative measurements during one actuating cycle for three different frequencies 10

20

30 Hz are obtained.The PIV measurements rdisplay the properties and structures of the unsteady flow field.Detailed study shows that in the current experiment

with fixed orifice scale and increasing frequency

the corresponding average orifice velocity U0 and stroke length L0 increase.While with constant driving frequency and increasing aspect ratio

both average orifice velocity U0 and stroke length L0 decrease.Also with increasing thickness of the orifice plate d

the friction in the orifice channel increases

consequently the average orifice velocity U0 and stroke length L0 decreases.Time-averaged flow field obtained by 350 image pairs overlapped shows the similarity of dimensionless cross-stream velocity profile and the centerline velocity decay ratio of synthetic jet in the fully developed segment is higher than the conventional 2D free jet.