Numerical Simulation of Breakup of Elliptical Liquid Jet in Still Air

Farvardin, Ehsan; Dolatabadi, Ali

doi:10.1115/fedsm2012-72307

Cited by 9 publications

(7 citation statements)

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“…Researchers have used the VOF model to simulate the two-phase flow of nozzle, bearing, and gear [25][26][27][28][29] and the primary breakup of the liquid jet. 30,31 The VOF model was developed by Hirt and Nichols 32 in 1981, which can model two or more immiscible fluids by solving a single set of momentum equations. For the oil-gas two-phase flow inside the under-race lubrication system, a volume fraction α oil is solved to describe the oil phase in the VOF model.…”

Section: Two-phase Flow Modelmentioning

confidence: 99%

Numerical simulation on the oil capture performance of the oil scoop in the under-race lubrication system

Jiang

Liu

Lyu

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part G:

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The under-race lubrication system providing a moderate amount of oil to high-speed bearings is one of the key factors to ensure its good lubrication and cooling. To investigate the oil capture performance of the oil scoop, a complete numerical calculation model was established, and unsteady simulations of oil–gas two-phase flow inside the under-race lubrication system were carried out. The results indicate that the oil capture efficiency increases first and then decreases with increasing rotating speed at different oil jet velocities. The ratio of the rotating Reynolds number of the oil scoop to the Reynolds number of the oil jet corresponding to the maximum oil capture efficiency changes linearly with oil jet velocity. There are three variation trends of oil capture efficiency at different rotating speeds with the increase of oil jet velocity: monotonically decreasing, first increasing, and then decreasing and monotonically increasing. However, the amount of oil captured by the oil scoop increases monotonically under all operating conditions. The effect of oil temperature on oil capture efficiency is mainly due to the change of dynamic viscosity of the oil. The oil capture efficiency can be improved by appropriately increasing the oil temperature within a certain temperature range.

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Section: Two-phase Flow Modelmentioning

confidence: 99%

Numerical simulation on the oil capture performance of the oil scoop in the under-race lubrication system

Jiang

Liu

Lyu

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part G:

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show abstract

“…To better track the trends, the results were divided into two sets. The results of LD(3), LD (6) and LD(10) nozzles were separated from LD(20), LD(40) and LD(60) nozzles. In contrast to the wavelength, it was found that the entrance length directly influenced the amplitude.…”

Section: Axis-switching Characteristicsmentioning

confidence: 99%

“…The axis-switching phenomenon and jet breakup in low speeds were also investigated through numerical simulations conducted by Farvardin and Dolatabadi. 6 It was analytically found by Pillai et al 7 that axis-switching was not the only source of instability for elliptical jets and even in the absence of axis-switching, an elliptical jet was less stable than a circular jet, apparently owing to its interfacial curvature effects. Recently, the axis-switching amplitude of free-falling elliptical jets was further examined by Ma and Zhu.…”

Section: Introductionmentioning

confidence: 98%

Entrance length effects on the flow features of rectangular liquid jets

Aliyoldashi

Tadjfar

Jaberi

2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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An experimental study was carried out to investigate the effects of entrance length on the main characteristics of rectangular liquid jets discharged into the stagnant atmosphere. Six rectangular nozzles, all with the same aspect ratio of 3 but with different entrance length ratios ranging from 3.3 to 60 were constructed. The physics of the fluid flows was visualized by the aid of backlight shadowgraph technique and high speed photography. Flow visualizations revealed that in the mid-range of Weber numbers, the perturbations induced over the liquid surface remarkably depended on the entrance length ratio. Moreover, the characteristics of the axis-switching instability of rectangular liquid jets were measured. It was found that axis-switching wavelength was independent of the entrance length, while the amplitude of axis-switching was directly influenced. For entrance length ratios smaller than 10, the amplitude was increased with increase of entrance length, whereas for entrance length ratios higher than 10, this trend was reversed. Measurements of breakup length also showed that the transition of flow regimes was not perceptibly affected by the entrance length.

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“…One may note that the jets' transitioned liquid core for both cases show surface features pertaining to low Re turbulent behavior. In order to fully characterize such perturbations and to resolve the surface waves in jets due to turbulence, previous studies by Farvardin and Dolatabadi (2013) have pointed out that a full 3D model using Large Eddy Simulations (LES) together with VOF method would be more ideal. We also envisage that the choice of LES-VOF should resolve such higher order surface effects and further enhance the agreement between predicted average jet lengths with experimentally determined results from Sallam et.…”

Section: Jetting: Varying Jet Breakup Length and Coalescence Of Dropsmentioning

confidence: 99%

Breakup and coalescence of drops during transition from dripping to jetting in a Newtonian fluid

Viswanathan

2019

International Journal of Multiphase Flow

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We present numerical simulations of dripping to jetting transitions that occur during the flow of a Newtonian liquid. An axis-symmetric, Volume of Fluid (VOF) model along with Continuum Surface Force (CSF) representation is developed to capture various regimes of drop formation. By numerically studying different nozzle diameters subjected to various flow rates, we examine the critical conditions under which the dripping to jetting transition takes place. At every stage of dripping and jetting, we assess the accuracy of the present simulations through a number of comparisons with previously published experimental data and empirical correlation and find reasonable agreements. Our numerical simulations show different responses that characterize the dripping and the dripping faucet regimes leading to chaotic dripping patterns. Within the chaotic regime, we identify four unique modes of satellite formation and their merging patterns which have not been reported earlier. Finally, we observe that as soon as the flow rate approaches a threshold the jetting regime begins where, subsequent disintegration of drops and coalescence patterns are observed downstream. Detailed flow patterns, pressure distributions and drop shapes are provided for various dimensionless numbers alongside the spatial-temporal resolutions of both jetting and coalescence of primary drops. Of the many complex dynamics that influence the primary droplet coalescence, we find that the oscillatory motion of drops during their travel downstream, which is dampened normally due to viscous effects, can be influential and can aid both coalescence and breakup of droplets.

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Numerical Simulation of Breakup of Elliptical Liquid Jet in Still Air

Cited by 9 publications

References 0 publications

Numerical simulation on the oil capture performance of the oil scoop in the under-race lubrication system

Numerical simulation on the oil capture performance of the oil scoop in the under-race lubrication system

Entrance length effects on the flow features of rectangular liquid jets

Breakup and coalescence of drops during transition from dripping to jetting in a Newtonian fluid

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