INSTABILITY PROCESSES IN MELT ATOMIZATION

摘要

For spray forming applications and metal powder production, the liquid metal is often atomized by twin fluid gas atomization. In a typical free fall atomizer the liquid melt undergoes different stages of break up. An overview of this multistage atomization process will be given. The first stage of the atomization process is the initialisation and development of surface perturbations that subsequently grow and finally lead to the breakup of the liquid jet. The primary disintegration process may have an effect on all further stages of the atomization process and hence the resulting spray characteristics. Surface instabilities of liquid metal jets and the region of ligament breakup in an early stage, as well as regions of high droplet density have been analysed experimentally by high speed video images. As a result the periodicity of the initialisation process and of the mechanisms of breakup will be discussed. An insight in the droplet velocity distribution in dense spray regions is given.