Simulation and numerical analysis of the peripheral airflow field of atomized Fe-58％Sn alloy microdroplet
Based on the k-ε turbulence model,the peripheral airflow field of Fe-58％Sn immiscible alloy droplets is numerically simulated during its cooling process in the gas flow. By analyzing the flow and heat transfer proce-dures,the heat transfer coefficients h at each surface are determined,and the position of the "core" inside a pow-der is predicted. The results show that the average airflow velocity on the windward side of micro-droplet is low-er than that of the inlet gas,but it is higher than the airflow on the leeward side. Both the airflow velocity v and the heat transfer coefficient h on the micro-droplet surface are strongly dependent on the rotation angle θ,which first increase and then decrease as the rise in θ( 0＜θ＜π). The values of v and h reach the peaks at θ=2π/5,and they become the smallest ones at θ=π,and moreover the peak positions are independent of the micro-droplet di-ameter. Furthermore,the calculation results demonstrate that there is a little effect of micro-droplet size on the pe-ripheral gas flow field,and the maximum differences of heat transfer coefficient in the 10 m/s flow field for alloy micro-droplets with diameters of 400,600 and 800 μm are 727.8,779.7 and 836.7 W·(m-2 K-1),respectively. In addition,the different heat transfer condition contributes to the fact that the inner "core" structure is continuously shifted from the geometric center of the micro-droplets to the leeward side,eventually forming a core-off-center core/shell structure morphology after solidification. This study is of great significance to reveal the formation mechanism of the core-shell structure and the materials design of new intelligent structure.
immisciblemicro-dropletflow fieldk-ε modelheat transfer
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