Capillary instability of elliptic liquid jets

Amini, Ghobad; Dolatabadi, Ali

doi:10.1063/1.3626550

Cited by 48 publications

(12 citation statements)

References 24 publications

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“…It is proved that the dynamic surface tension is more appropriate than the static surface tension to study the spray characteristics of surfactant solutions and suspensions [136]. Measurements of oscillating free jets, where a fluid comes out of an elliptical nozzle, together with an analytical model have long been used to determine the dynamic surface tension [137][138][139][140][141][142][143][144][145]. Noticeably, the value of the surface tension of pure fluid can only be applied for a dilute suspension with a low concentration of surfactant.…”

Section: Suspension Propertiesmentioning

confidence: 99%

A Comprehensive Review on Fluid Dynamics and Transport of Suspension/Liquid Droplets and Particles in High-Velocity Oxygen-Fuel (HVOF) Thermal Spray

2015

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Abstract:In thermal spraying processes, molten, semi-molten, or solid particles, which are sufficiently fast in a stream of gas, are deposited on a substrate. These particles can plastically deform while impacting on the substrate, which results in the formation of well-adhered and dense coatings. Clearly, particles in flight conditions, such as velocity, trajectory, temperature, and melting state, have enormous influence on the coating properties and should be well understood to control and improve the coating quality. The focus of this study is on the high velocity oxygen fuel (HVOF) spraying and high velocity suspension flame spraying (HVSFS) techniques, which are widely used in academia and industry to generate different types of coatings. Extensive numerical and experimental studies were carried out and are still in progress to estimate the particle in-flight behavior in thermal spray processes. In this review paper, the fundamental phenomena involved in the mentioned thermal spray techniques, such as shock diamonds, combustion, primary atomization, secondary atomization, etc., are discussed comprehensively. In addition, the basic aspects and emerging trends in simulation of thermal spray processes are reviewed. The numerical approaches such as Eulerian-Lagrangian and volume of fluid along with their advantages and disadvantages are explained in detail. Furthermore, this article provides a detailed review on simulation studies published to date. OPEN ACCESSCoatings 2015, 5 577

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Section: Suspension Propertiesmentioning

confidence: 99%

A Comprehensive Review on Fluid Dynamics and Transport of Suspension/Liquid Droplets and Particles in High-Velocity Oxygen-Fuel (HVOF) Thermal Spray

2015

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“…The current study is limited to the modes with the lowest transverse order m = 0, because only this mode dominates the unstable fluid flow and the higher order eigenmodes are more oscillatory and are not frequently encountered at low to medium jet speeds. [6][7][8] By enforcing periodicity of the solution, Eq. (20) can be written as…”

Section: Local Linear Stability Analysismentioning

confidence: 99%

Instability of elliptic liquid jets: Temporal linear stability theory and experimental analysis

Amini

Dolatabadi

et al. 2014

Physics of Fluids

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The instability dynamics of inviscid liquid jets issuing from elliptical orifices is studied, and effects of the surrounding gas and the liquid surface tension on the stability behavior are investigated. A dispersion relation for the zeroth azimuthal (axisymmetric) instability mode is derived. Consistency of the analysis is confirmed by demonstrating that these equations reduce to the well-known dispersion equations for the limiting cases of round and planar jets. It is shown that the effect of the ellipticity is to increase the growth rate over a large range of wavenumbers in comparison to those of a circular jet. For higher Weber numbers, at which capillary forces have a stabilizing effect, the growth rate decreases with increasing ellipticity. Similar to circular and planar jets, increasing the density ratio between gas and liquid increases the growth of disturbances significantly. These theoretical investigations are complemented by experiments to validate the local linear stability results. Comparisons of predicted growth rates with measurements over a range of jet ellipticities confirm that the theoretical model provides a quantitatively accurate description of the instability dynamics in the Rayleigh and first wind-induced regimes. C 2014 AIP Publishing LLC. [http://dx.

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“…The reason can be attributed to the enhanced instability of elliptical jets. Amini and Dolatabadi [22] studied the capillary instability of an elliptical liquid jet. They stated that the elliptic jet is more unstable in comparison with a circular jet.…”

Section: A Spray Featuresmentioning

confidence: 99%

Effects of orifice geometry on spray characteristics of impinging jet injectors for gelled propellants

Yang

Zhuang

2013

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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1 This paper presents the results of an experimental study on breakup characteristics of gelled propellant liquid sheets formed by impinging jet injectors with different geometries of injector orifice (round, elliptic, and rectangular shape). Spray formation of gelled propellant from impinging jet injectors was described by carrying out experiments in a spray test facility. Considering the safety, a water based gel simulant was used instead of the gelled propellant in the experiments. The rheological characteristics of the gel simulant were tested. A high speed camera was used to grab the detailed information of the liquid sheet breakup process and spray development. The experiments were performed with injectors of different shape of injector orifice to test the geometrical effect of injector orifice on the spray characteristics. The experimental results showed that under the condition of identical sectional area, the shapes of liquid sheet formed by the impinging jet injectors with different shape of orifices were different. One special phenomenon is the thick liquid stream in the center of liquid sheet when the aspect ratio of rectangular orifice is great. The reason of this phenomenon is the axis-switching feature of the non-circular jets. The mass flow rates of square and elliptical orifices are larger than that of circular orifice. The flow rate of rectangular orifice becomes greater as the aspect ratio gets larger. The breakup length for injector with square orifice is shorter than that for injector with circular orifice. Although the elliptical jet behaves greater instability than circular jet, the liquid sheet breakup length of injector with elliptical orifice is not always shorter than that of injector with circular orifice. Generally, the breakup length of rectangular jet impinging injector increases with aspect ratio.

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Capillary instability of elliptic liquid jets

Cited by 48 publications

References 24 publications

A Comprehensive Review on Fluid Dynamics and Transport of Suspension/Liquid Droplets and Particles in High-Velocity Oxygen-Fuel (HVOF) Thermal Spray

A Comprehensive Review on Fluid Dynamics and Transport of Suspension/Liquid Droplets and Particles in High-Velocity Oxygen-Fuel (HVOF) Thermal Spray

Instability of elliptic liquid jets: Temporal linear stability theory and experimental analysis

Effects of orifice geometry on spray characteristics of impinging jet injectors for gelled propellants

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