SBIR-STTR Award

The objective of this project is to develop a droplet generator that produces a rectangular array of 112 streams of droplets, all travelingin parallel paths. The orifices can be of the same diamenter so thatall the drops will be the same diameter or the orifices can be of several diameters and several species of drops will be produced. The fluid orifices will be made using the process used to make bimetal masks for photolithography and the orifice diameters can be made from 40 to 400 microns. Piezoelectric drivers will provide the acoustic stimulation for uniform drop formation. We will measure the vibrational modes of the orifice plate and the effect of orifice plate mounting on thesemodes. We can measure the deviations of the individual streams for parallel and how these deviations vary with fluid operating pressure and the orifice mounting method. Other research topics to be studied are corrosion resistance of the orifice plate, the jet diameter uniformity, the jet velocity uniformity, and the range of fluid viscosity and surface tension that will operate with the drop generator.

The two processes used to make a monodisperse droplet spray are the formation of a liquid jet and the acoustic excitation of the jet to cause it to break into drops at the excitation frequency. Monodisperse drop generators contain three components: the nozzle or nozzles for jet formation, a transducer for making acoustic vibrations, and a mechanical structure that carries the vibrations to the jets. This proposal describes a project for improvements in all three components. The major portion of the effort will be to experimentally and numerically study several acoustic transmission structures. The transmission structures' vibrational modes will be determined experimentally and a finite element numerical analysis will also be made. The goal is to develop models of the acoustic transmission structure so that long, up to two meters, monodisperse drop generators can be designed. Measurements of the acoustic amplitude and frequency will be made on small flow generators to establish the initial conditions required for jet breakup. Nozzle plates will be made that form jets whose paths diverge and droplet generators incorporating these plates will be made.