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.
Hadiseh Karimaei; Mostafa Hossein Alipour; F Ommi; Ehsan Movahednejad; Reza Sharifzadeh
Volume 10, Issue 4 , March 2018, , Pages 1-7
Abstract
A swirl injector is tested to investigate the instability of the liquid sheet emanating from it and determine the main microscopic characteristics of the spray. The injector, which is tested, was already approved by doing the characterization tests (macroscopic). Due to the fact that the PDPA systems ...
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A swirl injector is tested to investigate the instability of the liquid sheet emanating from it and determine the main microscopic characteristics of the spray. The injector, which is tested, was already approved by doing the characterization tests (macroscopic). Due to the fact that the PDPA systems to measure the spray characteristics are very expensive and high-tech, and therefore inaccessible for us , it is attempted to investigate the specifications and instability of the liquid sheet as much as possible, by photography. The liquid sheet emanating from the injector has perturbations on its surface which originate from inside the injector. Due to the aerodynamic interactions, these perturbations grow and eventually lead to break up the liquid sheet and form the ligaments. The growth of these unstable waves can be observed in the images. Also the breakup length can be measured using the images recorded. Also ligaments in the primary breakup zone and droplets were shown.
Hadiseh Karimaei; seyed mostafa hosseinalipour
Volume 10, Issue 3 , December 2017, , Pages 59-65
Abstract
The droplet formation stage of a spray, which enjoys a great diversity in size and droplet velocity, is predictable through a statistical approach. Since the available methods require experimental data such as mean droplet diameter and mean droplet velocity as inputs to estimate the distribution of the ...
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The droplet formation stage of a spray, which enjoys a great diversity in size and droplet velocity, is predictable through a statistical approach. Since the available methods require experimental data such as mean droplet diameter and mean droplet velocity as inputs to estimate the distribution of the droplets, this study attempts to propose a consistent theoretical model based on the energy conservation equation for the estimation of mean droplet diameter to be used in the predictive models of droplet size distribution, such as maximum entropy model. Therefore, those models can be independent of experimental data. The parameters needed in the model, such as atomization efficiency and the Weber number are provided using a CFD model. Then, a parametric study to evaluate the relationship between the atomization efficiency and spray velocity, and mean droplet diameter is carried out. This new proposed model entitled energy-based model (EBM) can provide a very good prediction of mean droplet diameter in comparison with the available experimental data.
