Gas Velocities from Free Fall Gas Atomiser

Abstract

The flow field of a free fall gas atomiser has been measured in three dimensions using hot wire anemometry and a pitot tube for confirmation of axial flow speeds. A finite difference based fluid dynamics package has then been used to model the gas flow from the atomiser geometry. Overall a close fit for the velocity magnitudes was obtained for predictions parallel to and along the central axis of the atomiser. An exception was a broader but lower peak along the central axis. Hot aluminium droplets of a distribution reproduced from experimental atomisation were injected into the gas flow at the confluence of the gas jets along the central axis. The modified gas flow pattern is specifically altered, when compared to the original single phase flow, close to the axis where the droplets travel. The resulting mass flowrate at the axial peak flow corresponds to that expected from the law of conservation of momentum. PM/0714