Spray nozzle for fluid deposition

摘要

A fluid spray nozzle that mixes a pressurized gaseous propellant and paint composition prior to being applied to a workpiece. The nozzle includes an upstream section for receiving the pressurized gaseous propellant. The nozzle directs the gaseous propellant and the fluid composition into a recirculation cavity. The gaseous propellant and fluid composition are received in a downstream section after mixing in the recirculation cavity. The recirculation cavity has lobes on opposite sides of a flow path defined in a region in the recirculation cavity between an inlet opening and the recirculation cavity. The recirculation cavity is formed by silicon micromachining the upstream section, fluid injection section, recirculation cavity and downstream section. The gaseous propellant may be accelerated to supersonic speeds prior to entering the recirculation cavity. The gaseous propellant and fluid composition are decelerated to subsonic speeds prior to exiting the downstream section, thereby resulting in the formation of a shock wave at the transition from supersonic to subsonic speeds which causes further atomization of the fluid composition.