2 PHASE FLOW MODEL FOR THE CLOSE-COUPLED ATOMIZATION OF METALS

The use of the nozzle tip static (aspiration) pressure during the flow of atomizing gas in close-coupled atomization geometries is employed widely to characterize the operable atomization regime, and, in some c ases, the expected metal flow rate. A single phase flow calculation of metal flow rate using this pressure shows that the actual metal flow during atomization is not determined simply by the aspiration pressure . An improved model has been developed by applying a force balance and momentum conservation at the metal/gas interface. Combined with numer ical and experimental gas flow data, the model provides a rational int erpretation of the relationship between aspiration pressure and metal flow during atomization. The model also provides a physical basis for some of the commonly observed limits on the operating envelope of clos e-coupled atomizers and establishes a rational basis for non-metal flu id modeling of the atomization process. A variety of metal and wafer f low test data and local static and dynamic pressure measurements are p resented which demonstrate the validity and limitations of the model.