Experimental investigation of aerosol jets from micronozzles

An aerosol jet generated by the expansion of an aerosol gas suspension from different micro-nozzles was studied. The particle velocity was measured by a Fabry-Perot laser Doppler anemometer. The width and the structure of the jet was evaluated by direct optical investigation. Comparative measurements show that Laval nozzles are more suitable for the generation of rapid, intense aerosol jets than orifices, because the internal energy of the carrier-gas molecules is transformed into unidirectional kinetic energy. Separation of the gas jet in the divergent part of the Laval nozzle leads to focusing effects of the aerosol jet and thus the expansion angle remains small. The particles, which are accelerating large distances, gain high velocities. Comparison of the measured velocities with models shows relatively good agreement. Nozzles for accelerating aerosol jets are proposed.