Micropropulsion of air and liquid jet by acoustic streaming

This paper describes an ultrasonic, nozzleless jet propeller that can shoot out jet streams of liquid or air (from a spot of hundreds of micron in diameter) through an acoustic streaming effect. The propelled jet streams of liquid contain atomized liquid particles of 3 to 10 microns in diameter, and move at a rate as high as 37.5 /spl mu/l/s. In case of air, the speed of the propelled air jet can reach up to 1.2 m/s. This is the first time that acoustic streaming effect is experimentally confirmed in air at such a high frequency of 10.8 MHz.