Computational Analysis on Primary Breakup and Deformation of Kerosene Jet in Subsonic Cross Flow Using VOF Method

Abstract

The main objective of this computational analysis is to investigate the effect of increase in Weber number at constant momentum flux ratio on the primary breakup process and deformation of kerosene jet in cross stream air flow. Unsteady computational analysis with VOF approach is carried out to simulate the two phase flow at three different cross flow Weber number conditions (150, 350 and 400) at constant momentum flux ratio of 17. Since the results of VOF technique is highly sensitive to the size and distribution of grid, grid optimization process is carried out, with both structured and unstructured forms of the grid. Since the structured grid with number of elements 17,96,181 displayed better matching with experimental results of upper trajectory of kerosene jet; this grid is used to investigate the effect of turbulence model and Weber number on the windward trajectory of kerosene jet in cross flow air stream. Initially to evaluate the results of computational analysis; simulations are carried out with larger computational domain (with number of elements 17,96,181). Windward trajectory of computational analysis is compared with experimental results of upper trajectory predicted using image processing technique and reasonable overall matching is observed. To investigate the primary breakup process and deformation of liquid jet at three different increasing Weber number conditions, simulations are carried out with smaller computational domain with higher mesh density with number of elements 33,96,146. The computational technique used in the present analysis exactly captures the modes of breakup observed from experimental results at different Weber number operating conditions. To characterize the deformation of liquid jet at different Weber number conditions; near-field trajectory, cross stream dimension and wave length of liquid jet are quantified at different instants of time. With increase in Weber number, decrease in penetration of liquid jet along transverse direction and more bending of liquid jet along flow direction is observed. From the velocity profile along transverse direction of three different conditions, stronger shearing of liquid film is observed in higher Weber number conditions.