CFD Trials for Comparative Evaluation and Recommendation of Nozzle Geometry for Gas Atomization of Aluminum Alloys

Atomization is often chosen as one of the powder production techniques because of high production rates and ability to make alloy powders of the desired composition. In gas atomization process, the liquid metal is broken into droplets to form the powders upon solidification. Gas-metal interaction influences the break-up of liquid stream in to droplets. Geometry of the nozzle governs the gas-metal interaction. Selection of nozzle type and the flow geometry is the most important parameter for gas atomization process. Design of nozzle determines the degree of contact of liquid metal with the atomizing gas. The atomizing nozzles have co-axially placed Metal Delivery Tube (MDT), which carry the molten metal to atomizing zone. Flow properties of gas are considerably affected by the presence of MDT. In the present analysis, an attempt has been made to compare Convergent nozzle (C - nozzle) and Convergent- Divergent (CD) nozzle for parameters like flow and heat transfer aspects using CFD technique. Further, DAR (Decision Analysis and Resolution) a CMMI (Capability Maturity Model, Integration technique) was adopted to recommend a nozzle configuration for gas atomization of the aluminum alloys.