Liquid Jet Instability and Atomization in a Coaxial Gas Stream

Lasheras, Juan C.; Hopfinger, Emil J.

doi:10.1146/annurev.fluid.32.1.275

Cited by 466 publications

(346 citation statements)

References 53 publications

Supporting

Mentioning

325

Contrasting

Order By: Relevance

“…The physical mechanisms of primary atomization are often complex, nonlinear and hence, are poorly understood. This is true not only for co-flowing gas-liquid mixing layers but also for jets [4][5][6] , planar sheets 7 , etc. In this article, the primary atomization process in a co-flowing gas-liquid mixing layer is illustrated, in particular, when the horizontal gas flow is fast.…”

Section: Introductionmentioning

confidence: 99%

Vortices catapult droplets in atomization

et al. 2013

View full text Add to dashboard Cite

A droplet ejection mechanism in planar two-phase mixing layers is examined. Any disturbance on the gas-liquid interface grows into a Kelvin-Helmholtz wave and the wave crest forms a thin liquid film that flaps as the wave grows downstream. Increasing the gas speed, it is observed that the film breaks-up into droplets which are eventually thrown into the gas stream at large angles. In a flow where most of the momentum is in the horizontal direction, it is surprising to observe these large ejection angles. Our experiments and simulations show that a recirculation region grows downstream of the wave and leads to vortex shedding similar to the wake of a backward-facing step. The ejection mechanism results from the interaction between the liquid film and the vortex shedding sequence: a recirculation zone appears in the wake of the wave and a liquid film emerges from the wave crest; the recirculation region detaches into a vortex and the gas flow over the wave momentarily reattaches due to the departure of the vortex; this reattached flow pushes the liquid film down; by now, a new recirculation vortex is being created in the wake of the wave-just where the liquid film is now located; the liquid film is blown-up from below by the newly formed recirculation vortex in a manner similar to a bag-breakup event; the resulting droplets are catapulted by the recirculation vortex.

show abstract

Section: Introductionmentioning

confidence: 99%

Vortices catapult droplets in atomization

et al. 2013

View full text Add to dashboard Cite

show abstract

“…[17][18][19][20] It is, therefore, important to examine how small changes in the fuel physical properties of the fuel may affect the liquid jet development at that location of the nozzle.…”

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

“…One approach to modelling the spray is to use a PDF to represent the probable number of droplets with certain diameters and velocities in a given region [13][14][15][16][17]. The RosinRammler distribution was suggested [18] and has been found to be appropriate for many types of atomization spray [19].…”

Section: Introductionmentioning

confidence: 99%

Size distributions of sprays produced by violent wave impacts on vertical sea walls

Watanabe

Ingram

2016

Proc. R. Soc. A.

View full text Add to dashboard Cite

When a steep, breaking wave hits a vertical sea wall in shallow water, a flip-through event may occur, leading to the formation of an up-rushing planar jet. During such an event, a jet of water is ejected at a speed many times larger than the approaching wave's celerity. As the jet rises, the bounded fluid sheet ruptures to form vertical ligaments which subsequently break up to form droplets, creating a polydisperse spray. Experiments in the University of Hokkaido's 24 m flume measured the resulting droplet sizes using image analysis of high-speed video. Consideration of the mechanisms forming spray droplets shows that the number density of droplet sizes is directly proportional to a power p of the droplet radius: where p = −5/2 during the early break-up stage and p = −2 for the fully fragmented state. This was confirmed by experimental observations. Here, we show that the recorded droplet number density follows the lognormal probability distribution with parameters related to the elapsed time since the initial wave impact. This statistical model of polydisperse spray may provide a basis for modelling droplet advection during wave overtopping events, allowing atmospheric processes leading to enhanced fluxes of mass, moisture, heat and momentum in the spraymediated marine boundary layer over coasts to be described.

show abstract

Liquid Jet Instability and Atomization in a Coaxial Gas Stream

Cited by 466 publications

References 53 publications

Vortices catapult droplets in atomization

Vortices catapult droplets in atomization

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

Size distributions of sprays produced by violent wave impacts on vertical sea walls

Contact Info

Product

Resources

About