Hadiseh Karimaei; Ramin Ghorbani; Seyed Mostafa Hoseeinalipour
Volume 11, Issue 4 , December 2018, , Pages 1-10
Abstract
In the atomization process, small disturbances grow in liquid jet or sheet and eventually cause to disintegrate it into ligaments and smaller droplets. Concerning to the motion of waves on the liquid sheet surface, the stage of primary breakup is deterministic and can be predicted by instability analyzes. ...
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In the atomization process, small disturbances grow in liquid jet or sheet and eventually cause to disintegrate it into ligaments and smaller droplets. Concerning to the motion of waves on the liquid sheet surface, the stage of primary breakup is deterministic and can be predicted by instability analyzes. In early studies, the theories of linear and weakly nonlinear instability have been implemented on a cylindrical liquid sheet and the effect of spray cone angle was not included in the model. Therefore, in this paper in order to improve the model, the linear instability theory is implemented on a cone-shaped liquid sheet for the first time, and therefore radial velocities of liquid and gas phases are also considered moreover than axial and tangential velocities. The results of this improved model such as maximum wave growth rate and its corresponding wave number can be used to estimate mean droplet diameter and breakup length.
F. Ommi; S. Askari Mahdavi; S. M. Hosein- Alipour; E. Movahed-Nezhad
Volume 4, Issue 1 , July 2011, , Pages 39-48
Abstract
A linear instability analysis of an annular liquid sheet emanating from an atomizer subjected to inner and outer air streams to investigate the liquid viscosity and swirl velocity on the maximum growth rate has been carried out. The dimensionless dispersion equation that governs the instability of a ...
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A linear instability analysis of an annular liquid sheet emanating from an atomizer subjected to inner and outer air streams to investigate the liquid viscosity and swirl velocity on the maximum growth rate has been carried out. The dimensionless dispersion equation that governs the instability of a viscous annular liquid sheet under air streams was derived with linear stability analysis. The dispersion equation solved by numerical method and investigated viscosity and swirl velocity effect on maximum growth rate and its corresponding unstable wave number. The results show that decrease in viscosity has positive effect on maximum growth rate and its corresponding unstable wave number. At low liquid swirl Weber number liquid swirl has a stabilizing effect and at high liquid swirl Weber number liquid swirl velocity has a destabilizing effect on the liquid sheet. The growth rate can be related to the breakup length of the liquid sheet and when the growth rate increase, breakup length was shorter. The drop diameter dependent to the wave number and decrease with increase on it that afford to improvement the combustion and decrease the specific fuel consumption.
F. Ommi; A. Kargar; S. M. Hosseinalipour
Volume 2, Issue 1 , April 2009, , Pages 51-57
Abstract
Optimized injectors spray and consequently their proper fluid distribution is one of the most important factors determining the thrust force and combustion stability. Reaching a stable combustion with a high specific impulse needs a proper fuel distribution and atomization. Asymmetric distribution of ...
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Optimized injectors spray and consequently their proper fluid distribution is one of the most important factors determining the thrust force and combustion stability. Reaching a stable combustion with a high specific impulse needs a proper fuel distribution and atomization. Asymmetric distribution of fuel spray droplets lead to asymmetric spray cone and incomplete combustion that cause the chamber broken. Regarding to the numerous advantages of swirl double-based injectors, 25 number of this injector type are manufactured to be mounted on a circular injector plate. To ensure that they have enough accuracy, macroscopic spray characteristic of all injectors are measured and examined in cold test lab and PDA lab.Having checked the quality of each injector, two types of injector plates are designed and manufactured precisely. Having manufactured a circular and a hexagonally arranged injector plate, their spray characteristics are examined.Results show that the circular injector plate has satisfactory spray characteristics like droplet distribution and desirable spray cone and could be ready for warm test.
