Phase Doppler Anemometry in Inert and Liquid Gas Atomization

Phase Doppler anemometry (PDA) and extended phase Doppler anemometry (EPDA) are used for the characterization of powders produced with different melt atomization techniques. A laboratory-scale, production-type melt spray facility was adapted for the application of PDA and measurements were performed in inert gas atomization (IGA) of melts. For liquid gas atomization (LGA) an extended phase Doppler system has been used, allowing a distinction between melt particles and liquefied gas droplets. In IGA, the results obtained with PDA show some discrepancies with off-line powder characterization techniques; however, variations of process conditions leading to changes in the powder size distributions could be detected, e.g., the decrease of the mean diameter of the powder with increasing atomizing pressure. Hence, a first attempt is presented of how phase Doppler anemometry can be incorporated in a process control loop. In LGA, liquefied gas droplets and melt droplets could be discriminated b y using the sign of the phase EPDA system. However, additional measurements are necessary to improve the reproducibility of the results.