Synthetic Jet Thrust Optimization for Application in Underwater Vehicles

Zero-mass pulsatile jets are proposed for low speed maneuvering and station keeping of small underwater vehicles. The flow field of such jets are initially dominated by vortex ring formation. Such pulsatile jets can be actuated through a variety of techniques. Two prototypes of such actuators, presented here, include a mechanical plunger system and a solenoid actuator. The actuators consist of a small cavity with an orifice on one side and a moving diaphragm on the other side. Oscillation frequencies are varied between zero and 40 Hz for the mechanical plunger and upto 50 Hz for the solenoid actuator. The mechanical actuator is designed so that the cavity dimensions, orifice diameter, actuation frequency, and actuation profile can be easily varied in order to find the optimal operation point of the actuator. Thrust measurement data is provided for various formation numbers while the actuation frequency in varied. The empirical thrust profiles were seen to follow the same trend as a model previously developed by our group. It is also observed that the measured thrust has a maximum value for formation numbers between 4 and 5.5 for various actuation frequencies and for two different cavity diameters. Solenoid actuation shows an almost linear stroke dependency on the actuation frequency.