Drop formation at the surface of plane turbulent liquid jets in still gases

Sallam, Khaled; Dai, Z.; Faeth, G. M.

doi:10.1016/s0301-9322(99)00042-7

Cited by 43 publications

(32 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, when scaling the characteristic droplet diameter of sprays from pressure atomisers on the surface tension, power law exponents ranging from −0.15 to 0.737 [9][10][11][12][13] have been quoted. While there are differences in the considered injector geometries and the flow conditions among the various investigation, from the breadth of the reported correlations, it is clear that no consensus exists.…”

Section: Introductionmentioning

confidence: 99%

How do liquid fuel physical properties affect liquid jet development in atomisers?

Charalampous

Hardalupas

2016

Physics of Fluids

View full text Add to dashboard Cite

The influence of liquid fuel properties on atomisation remains an open question. The droplet sizes in sprays from atomisers operated with different fuels may be modified despite the small changes of the liquid properties. This paper examines experimentally the development of a liquid jet injected from a plain orifice in order to evaluate changes in its behaviour due to modifications of the liquid properties, which may influence the final atomisation characteristics. Two aviation kerosenes with similar, but not identical physical properties are considered, namely standard JP8 kerosene as the reference fuel and bio-derived Hydro-processed Renewable Jet (HRJ) fuel as an alternative biofuel. The corresponding density, dynamic viscosity, kinematic viscosity and surface tension change by about +5%, -5%, -10% and +5% respectively, which are typical for ‘drop-in’ fuel substitution. Three aspects of the liquid jet behaviour are experimentally considered. The pressure losses of the liquid jet through the nozzle are examined in terms of the discharge coefficient for different flowrates. The morphology of the liquid jet is visualised using high magnification Laser Induced Fluorescence (LIF) imaging. Finally, the temporal development of the liquid jet interfacial velocity as a function of distance from the nozzle exit is measured from time-dependent motion analysis of dual-frame LIF imaging measurements of the jet. The results show that for the small changes in the physical properties between the considered liquid fuels, the direct substitution of fuel did not result in a drastic change of the external morphology of the fuel jets. However, the small changes in the physical properties modify the interfacial velocities of the liquid and consequently the internal jet velocity profile. These changes can modify the interaction of the liquid jet with the surroundings, including air flows in coaxial or cross flow atomisation, and influence the atomisation characteristics during changes of liquid fuels

show abstract

Section: Introductionmentioning

confidence: 99%

How do liquid fuel physical properties affect liquid jet development in atomisers?

Charalampous

Hardalupas

2016

Physics of Fluids

View full text Add to dashboard Cite

show abstract

“…Sallam et al [18] proposed correlations based on several previous pulsed photography and holography studies [4,17] (among others) to estimate the onset of primary breakup and mass flux from turbulent annular and round jets for nozzle exit conditions corresponding to unconditioned, fully developed turbulent pipe flow.…”

mentioning

confidence: 99%

Initial Conditions and Near-Field Dynamics in Turbulent Liquid Sheets

Durbin

Yoda

Abdel‐Khalik

2007

Flow Turbulence Combust

View full text Add to dashboard Cite

High-speed liquid "curtains" have been proposed to protect solid structures in fusion energy applications. Minimizing free-surface waves and spray formation in such flows is important for effective protection in this application. In this work, free-surface waves and turbulent breakup were studied experimentally in jets of water issuing from a rectangular nozzle into ambient air at a Reynolds number of 1.2×10 5 . Laser-Doppler anemometry was used to characterize the streamwise and transverse velocity components in the nozzle for two different flow calming section designs. Planar laser-induced fluorescence was used to measure the free-stream position in the near-field of the sheet. The results suggest that transverse velocity fluctuations in the nozzle are the primary factor in determining the amplitudes of free-surface waves. Removing a small amount of low-speed fluid immediately downstream of the nozzle exit ("boundary-layer cutting") is shown to both significantly reduce free-surface waves and the amount of spray due to turbulent breakup. Overall, boundary-layer cutting appears to have the greatest benefit when used on a "well-conditioned" turbulent liquid sheet.

show abstract

“…The experimental results by Hussein et al [17], Pitts [43], Liepmann et al [31], and Van de Sande et al [57] state that the nozzle exit flow conditions or the Reynolds number of the jet flow allow for the description of the variation of the entrainment intensity in the two-phase air/liquid free jet flow with downstream distance. From experiments by Sallam et al [47], Wong et al [61], and Wygnanski et al [62] emerged accordingly that the intensity of the air entrainment process is expected to be significant for establishing the droplet size distribution. In particular, the primary breakup of the liquid in the Core/Transition region yields fragments that are intrinsically weakened against the impact of the relatively large vortical structures and, therefore, prone to further deformation, so that these vortical air flow structures govern the local self establishing droplet size distribution in a two-phase free jet flow.…”

Section: Literature Surveymentioning

confidence: 99%

Prediction of Droplet Velocities and Rain Out in Horizontal Isothermal Free Jet Flows of Air and Viscous Liquid in Stagnant Ambient Air

Rabadi

Friedel

Surma³

2007

Chem Eng & Technol

View full text Add to dashboard Cite

Two-dimensional phase Doppler anemometer measurements of droplet size and velocity conducted under several nozzle conditions and a systematic variation of the air mass flow quality and liquid phase viscosity show that the air entrainment process is enhanced when keeping all test conditions constant except for increasing the Newtonian liquid viscosity above of that of water. A two-zone entrainment model based on a variable two-phase entrainment coefficient is proposed with the normalized axial distance allowing for a change in the jet angle. Thus, the jet perimeter is lower and the breakup length is longer in the case of air/relatively higher viscosity liquid phase. It provides the most accurate reproduction of the experimental droplet velocity in comparison with that of other models in the literature and, hence, is recommended for the prediction of the droplet velocity in the case of two-phase air/liquid phase free jet flow in stagnant ambient air. A model for predicting the droplet rain out, considering the droplet trajectories in the free jet flow, allows also for an adequate reproduction of the experimental data.

show abstract

Drop formation at the surface of plane turbulent liquid jets in still gases

Cited by 43 publications

References 20 publications

How do liquid fuel physical properties affect liquid jet development in atomisers?

How do liquid fuel physical properties affect liquid jet development in atomisers?

Initial Conditions and Near-Field Dynamics in Turbulent Liquid Sheets

Prediction of Droplet Velocities and Rain Out in Horizontal Isothermal Free Jet Flows of Air and Viscous Liquid in Stagnant Ambient Air

Contact Info

Product

Resources

About