Shiraz UniversityIranian Journal of Science and Technology Transactions of Mechanical Engineering2228-618737220131020ESTIMATION OF THE BREAKUP LENGTH FOR THE
ANNULAR AND THE ROUND LIQUID JET USING
LINEAR INSTABILITY ANALYSIS217232174910.22099/ijstm.2013.1749ENJournal Article20091119A linear instability analysis of an inviscid annular liquid sheet emanating from an<br />atomizer subjected to inner and outer swirling air streams and a non-swirl round liquid jet has been<br />carried out. The dimensionless dispersion equation that governs the instability was derived and<br />was solved by Numerical method to investigate the effects of the liquid-gas swirl orientation on<br />the maximum growth rate and its corresponding unstable wave number that produces the finest<br />droplets. To understand the effect of air swirl orientation with respect to liquid swirl direction, four<br />possible combinations with both swirling air streams with respect to the liquid swirl direction have<br />been considered. Results show that at low liquid swirl Weber number a combination of co-inner<br />air stream and counter-outer air stream has the largest most unstable wave number and shortest<br />breakup length. The combination of inner and the outer air stream co-rotating with the liquid has<br />the highest growth rate. Also, the results for round liquid jet and planar liquid sheet show that the<br />linear theory accurately predicts the variation in breakup length with jet velocity.Shiraz UniversityIranian Journal of Science and Technology Transactions of Mechanical Engineering2228-618737220131020EXPERIMENTAL, NUMERICAL ANALYSIS AND OPTIMIZATION OF
ELLIPTICAL ANNULAR FINS UNDER FREE CONVECTION233239175010.22099/ijstm.2013.1750ENJournal Article20120820This paper presents the total heat transfer rate by Elliptical Annular Fin (EAF) and<br />Circular Annular Fin (CAF) by experimental set-up, validated CFD analysis and optimization of<br />EAF using Genetic Algorithm (GA). The experimental result of EAF shows that, the surface<br />temperature of EAF goes on decreasing gradually along with the projected surface area in the<br />direction of the major axis. The STE decreases with the Biot number (Bi) and Shape factor (SF).<br />The rate of reduction of STE with increasing Bi is higher for Bi < 0.013. The experimental results<br />are validated with CFD result. The deviation is within acceptable range for surface temperature,<br />STE and fin effectiveness are 5-8%. The GA developed is validated with the experimental result. It<br />is observed that, the fin effectiveness is higher when the minor axis touches the circumference of<br />the CT, and for smaller values of SF and smaller values of the radius of the CT. This optimization<br />method is universal and may be used for optimization of EAF under specified volume.