TY - JOUR
T1 - Numerical comparison between the impact of a completely molten and a semi-molten hollow droplet on a surface
TT - مقایسه عددی برخورد یک قطره توخالی مذاب و یک قطره توخالی نیمه مذاب به سطح
JF - mdrsjrns
JO - mdrsjrns
VL - 17
IS - 8
UR - http://mme.modares.ac.ir/article-15-7464-en.html
Y1 - 2017
SP - 267
EP - 278
KW - semi-molten droplet
KW - VOF model
KW - Compressible flow
KW - Solidification
N2 - In this research, the impact of a completely molten hollow droplet and a semi-molten hollow droplet on a surface is simulated numerically. At first, the production process of hollow particles from the agglomerated particles is addressed analytically. By this model, one can predict the particle diameter, solid core diameter and shell thicknesses of produced particle. The results of this section show that hollow particle may hardly develop at small initial porosity values (p=0.2). Then, the collected data from analytical model is used as input data for numerical simulation. In the numerical model, the central solid core was assumed to be a fluid with high viscosity. Due to high impact velocity, volume and density changes of the trapped gas inside droplet are important. Therefore the compressible form of governing equations is used. The results show that the hydrodynamic and solidification behavior of a completely molten droplet and a semi-molten droplet during impact process are different. In the semi-molten state, the central solid core prevents the formation of a counter jet. For this reason, a hollow semi-molten droplet is solidified faster than a completely molten hollow droplet. The overall time of solidification in the completely molten state is 35 μs and the corresponding time for semi-molten state, is 12 μs. Moreover the splat of a semi-molten hollow droplet is more continues compared with a completely molten droplet
M3
ER -