Theoretical Analysis, Simulation and Experimental Investigation of Swirl Atomizers
Date Issued
2008
Date
2008
Author(s)
Chu, Chia-Chien
Abstract
In this study, theoretical analyses have been performed to investigate the effects of atomizer construction and controlled pressure difference of swirl atomizers. The analysis of fluid field in the swirl chamber is governed by mass/energy conservation rules; in the region outside the nozzle, the analysis of oscillation of liquid sheet is based on Squire`s expression for the amplitude growth rate. With some physical assumptions of control volume, initial values and model correlation, analytical results make it possible to predict film thickness, velocity distribution, spray cone angle and droplet size directly. The distribution of velocity profile and boundary layer thickness in the swirl chamber has been established with the aid of MATLAB. From the theoretical analysis, the equations for the droplet size, velocity components, the boundary layer thickness and the spray cone angle were deduced based on the fundamental governing equations. The purpose of the second stage is to establish a feasible model in FLUENT for the prediction of certain characteristics of swirl atomizers. The control variables in the simulations are pressure difference, nozzle geometries and the dependent variables are volume flow rate, spray cone angle and the resulting discharge coefficient. The purpose of the final stage of this study is to further compare the experimental result with the theoretical one already gained by a satisfactory embodiment of series of experiments. The aim is to corroborate the analytical results of the influence of atomizer construction and controlled pressure difference on typical swirl chambers. The results provide the droplet diameter as a function of pressure difference, swirl atomizer geometry, flow rate and spray cone angle. The experimental outputs also show good confirmation of theoretical results and can also be used for further optimization on existing swirl chambers. Based on the results obtained, an optimization methodology on characteristics of swirl atomizers is proposed with the adjustment of individual design parameter and the matching flow number.
Subjects
Swirl atomizer
droplet
spray cone angle
SDGs
Type
thesis
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