Abstract
We report direct numerical simulations of swirling liquid atomization to understand the physical mechanism underlying the sheet breakup of a non-turbulent liquid swirling jet which lacks in-depth investigation. The volume-of-fluid (VOF) method coupled with adapted mesh refinement (AMR) technique in GERRIS code is employed in the present simulation. The mechanisms of sheet, ligament and droplet formation are investigated. It is observed that the olive-shape sheet structure is similar to the experimental result qualitatively. The numerical results show that surface tension, pressure difference and swirling effect contribute to the contraction and extension of liquid sheet. The ligament formation is partially at the sheet rim or attributed to the extension of liquid hole. Especially, the movement of hairpin vortex exerts by an anti-radial direction force to the sheet surface and leads to the sheet thinness. In addition, droplet formation is attributed to breakup of ligament and central sheet.
Highlights
Spray combustion is a multi-scale, multiphase, and multi-physics process that is involved in propulsion system, such as aero-engine and gas turbine
The aim of the work presented in this paper is to study the mechanisms of sheet, ligament and droplet formation in swirling liquid atomization by using VOF method and adapted mesh refinement (AMR) technique
We report direct numerical simulation of swirling liquid atomization by using VOF method to capturing the gas-liquid interface and AMR technique to resolve the small liquid structure effectively
Summary
Spray combustion is a multi-scale, multiphase, and multi-physics process that is involved in propulsion system, such as aero-engine and gas turbine. Traditional spray combustion simulation employs atomized droplets as liquid inlet boundary condition,[1] where the liquid atomization process is eliminated. The liquid inlet boundary condition has significant effect on the combustion results. Som and Aggarwal[4] investigated the effect of different atomization models on the combustion characteristics and found out that the liquid penetration length, spray cone angle and axial velocity had discrepancy to some extent. This implies that the atomization model has limited accuracy. It is mostly attributed to the fact that the atomization process has not been fully understood, which results to variety of atomization models. It is imperious for us to investigate the liquid primary atomization phenomenon
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