Numerical Study of Primary Jet Breakup in a Simplex Swirl Atomizer Using Dual Grid Coupled Level Set VOF Method
01 Jan 2019-Vol. 2
TL;DR: In this article, the primary breakup of a liquid jet emanating from a simplex swirl atomizer is numerically studied in order to improve the curvature calculation, a dual grid approach is used.
Abstract:
Primary breakup of a liquid jet emanating from a simplex swirl atomizer is numerically studied in this work. The liquid-gas interface is tracked using a coupled Level-Set VOF method. In order to improve the curvature calculation, a dual grid approach is used. Level set function is solved on a grid that is finer than the grid used to solve the rest of the variables. This solver is developed using OpenFOAM libraries and is validated by estimating the pressure profile and spurious velocities across the interface of a static bubble. The validation test shows significant improvement in the performance of curvature estimation without significant increase in the computational cost. Additionally, it is found that curvature calculation improves with increase in grid refinement index. A parametric study to understand the effects of grid refinement index on the flow features of the simplex swirl atomizer primary jet is reported here.
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TL;DR: In this article, the effects of swirled inflows on the evaporation of dilute acetone droplets dispersed in turbulent jets are investigated by means of direct numerical simulation, based on a hybrid Eulerian-Lagrangian approach and the point-droplet approximation.
Abstract: The effects of swirled inflows on the evaporation of dilute acetone droplets dispersed in turbulent jets are investigated by means of direct numerical simulation. The numerical framework is based on a hybrid Eulerian–Lagrangian approach and the point-droplet approximation. Phenomenological and statistical analyses of both phases are presented. An enhancement of the droplet vaporization rate with increasing swirl velocities is observed and discussed. The key physical drivers of this augmented evaporation, namely dry air entrainment and swirl-induced centrifugal forces acting on the droplets, are isolated with the aid of additional simulations in which the inertial properties of the droplets are neglected. The correlation between swirl and dry air entrainment rate is found to be responsible for the increase of the global evaporation rate and the spray penetration length reduction, while swirl-induced centrifugal forces are found to be effective only in the jet shear layer, close to the injection orifice, for the analyzed cases.
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