ID 237

Comparative Analysis of Primary Atomization of Liquid Sheets And Films: A Numerical Approach

 

Abstract:

The efficiency of heat transfer in processes like combustion and spray cooling is highly dependent on the surface area exposed to the surrounding medium. The shapes (characterised by sphericity), sizes (equivalent diameter), as well as the number of droplets formed, are some of the most important parameters defining the overall behavior of an atomization process. The present study is focused on characterizing these parameters by parametric variations of different physical quantities e.g. velocity ratio, density ratio etc. An open source software, OpenFOAM’s inbuilt solver interFoam, which uses Volume of Fluid (VOF) method for interface capturing and Continuous Surface Force approach for modeling the effects of surface tension, is used for this purpose. A benchmark case is first performed (to validate the capacity and accuracy of the solver and schemes used) followed by the 2-D numerical simulations of liquid sheet disintegration (LSD) in the quiescent and co-flow medium. The velocity and density ratios are taken within a range from 2:5-1:5 and 1:10-1:200 respectively. Hydrodynamic instabilities and hence the side stripping increases with increase in velocity ratio for sheets. Increase in density ratio tends to destabilize the sheets which in turn gives rise to flapping phenomena. Droplet size distribution and primary breakup length are also studied for cases of liquid film disintegration (LFD) in co-flow medium and compared with that of the LSD. For all the cases, the thickness of injector wall which separates the liquid and the gas, has been neglected and a uniform velocity profile has been assumed for simplification.