Coaxial atomizer liquid intact lengths

Eroğlu, Hasan; Chigier, Norman; Farago, Zoltan

doi:10.1063/1.858139

Cited by 106 publications

(66 citation statements)

References 2 publications

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“…When scaling the results with the We number (Fig. 14a), the break-up length decreases according to a power law function of the We, in agreement with the suggestion of Eroglu et al [28]. For each value of Re L the break-up length appears to decrease in a power law fashion as the air co-flow (and the We number) is increased.…”

Section: Resultssupporting

confidence: 76%

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Structure of the Continuous Liquid Jet Core during Coaxial Air-Blast Atomisation

Charalampous

Hardalupas

Taylor

2009

International Journal of Spray and Combustion Dynamics

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This paper investigates the structure of the continuous liquid jet of a coaxial air-blast atomiser over a range of Weber numbers 60-1040, Reynolds numbers of liquid jet 5400-21700 and air to liquid momentum ratios of the two streams of 1.7-335. A novel optical technique, based on internal illumination of the liquid jet through the jet nozzle by a laser pulse, which excites a fluorescing dye introduced in the atomizing liquid, was used to obtain instantaneous measurements of the breakup length and the three dimensional location of the liquid core of the continuous liquid jet. The latter was achieved by simultaneously imaging the liquid jet from two directions normal to each other. Such measurements are usually prevented by droplets surrounding the liquid jet at the dense spray near the nozzle exit. The measurements showed that the break-up length of the liquid jet scaled well with the air to liquid momentum ratio. The standard deviation of the temporal fluctuations of the break-up length was around 10% of the mean breakup length for each considered flow condition. The instantaneous jet surface does not develop axi-symmetric wave structures but the time-averaged liquid jet is axi-symmetric around the nozzle axis, while the maximum deflection of the liquid jet occurs close to the breaking point.

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Section: Resultssupporting

confidence: 76%

“…The most common scaling approach has been suggested by Eroglu et al [28], and is based on the liquid Reynolds number: (1) and the aerodynamic Weber number:…”

Section: Figurementioning

confidence: 99%

Structure of the Continuous Liquid Jet Core during Coaxial Air-Blast Atomisation

Charalampous

Hardalupas

Taylor

2009

International Journal of Spray and Combustion Dynamics

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“…Measurements of both the liquid-core and dark-core lengths of a variety of different jets from photographs have been performed by others and reported in the past (see Eroglu et al [7]). However, the measurement methods are often not discussed in sufficient detail.…”

Section: Dark Core Measurementsmentioning

confidence: 99%

“…Much progress has been made since then and, as a result, we are approaching a fundamental understanding of fluid jet break up and atomization processes (see, for example, Lefebvre [6]). However, full understanding is not yet available (Eroglu et al [7]). A review of liquid jet atomization processes from a coaxial-type injector has recently been presented by Lasheras and Hopfinger [8], discussing some of the more recent developments in this area.…”

Section: Introductionmentioning

confidence: 98%

Measurements in an Acoustically Driven Coaxial Jet under Sub-, Near-, and Supercritical Conditions

Davis

Chehroudi

2007

Journal of Propulsion and Power

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An experimental investigation was conducted on a coaxial jet, similar to those used in cryogenic liquid rockets, under sub-, near-, and supercritical pressures, with the intent of gaining a better understanding of an aspect of combustion instability pertaining to interactions of an externally imposed acoustic field with the jet. Past research on this subject has shown both the relevance and importance of geometrical changes in an injector's exit-area and its nearby physical and fluid mechanical processes. Special attention is paid in collecting spatially resolved time averaged temperatures and documenting the aforementioned interactions at the exit of this injector. Short-duration and high-speed framing digital images provided information on the behavior of this jet under various conditions. Mean and root mean square values of the "dark-core" length fluctuations were measured from the acquired images via a computer-automated method, and results are discussed. There appears to be a good correlation between this length and the outer-to-inner-jet momentum ratio, but the form of this dependence was found to be different at subcritical pressures than the rest of the conditions. The root mean square values of the dark-core length fluctuations suggested a possible explanation for the observed improvement in instability limit at increasingly higher outer-toinner-jet velocity ratios. Nomenclature= diameter with subscripts L = length of dark core, length of injector tube M = momentum flux ratio of outer-jet to inner-jet m = mass flow rate n = exponent of M P = pressure R = radius with subscripts R h = hydraulic radius of outer-jet, equal to the gap width T = temperature U = velocity VR = velocity ratio of outer-jet to inner-jet = viscosity = density = surface tension Subscripts 1, 2, 3, 4 = four diameters or radii of the coaxial injector from the smallest to largest values i = subscript denoting inner-jet o = subscript denoting outer-jet

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“…A considerable amount of research has been performed on the development of liquid jets in gas environments, which can generally be classified in two categories. [4][5][6][7][8] In the first, the jet is injected into a quiescent environment as is the case of pressure atomisers. In the latter, a relatively slow moving central liquid jet is atomised by a high speed coaxial gas stream as is the case of air-blast atomisation.…”

Section: Introductionmentioning

confidence: 99%

Application of Proper Orthogonal Decomposition to the morphological analysis of confined co-axial jets of immiscible liquids with comparable densities

Charalampous

Hardalupas

2014

Physics of Fluids

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The development of a round liquid jet under the influence of a confined coaxial flow of an immiscible liquid of comparable density (central to annular flow density ratio of 8:10) was investigated in the vicinity of the nozzle exit. Two flow regimes were considered; one where the annular flow is faster than the central jet, so the central liquid jet is accelerated and one where the annular flow is slower, so the central liquid jet is decelerated. The central jet was visualised by high speed photography. Three modes of jet development were identified and classified in terms of the Reynolds number, Re, of the central jet which was in the range of 525 < Re < 2725, a modified definition of the Weber number, We, which allows the distinction between accelerating and deceleration flows and was in the range of −22 < We < 67 and the annular to central Momentum Ratio, MR, of the two streams which was in the range of 3.6 < MR < 91. By processing the time resolved jet images using Proper Orthogonal Decomposition (POD), it was possible to reduce the description of jet morphology to a small number of spatial modes, which isolated the most significant morphologies of the jet development. In this way, the temporal and spatial characteristics of the instabilities on the interface were clearly identified which highlights the advantages of POD over direct observation of the images. Relationships between the flow parameters and the interfacial waves were established. The wavelength of the interfacial instability was found to depend on the velocity of the fastest moving stream, which is contrary to findings for fluids with large density differences.

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Coaxial atomizer liquid intact lengths

Cited by 106 publications

References 2 publications

Structure of the Continuous Liquid Jet Core during Coaxial Air-Blast Atomisation

Structure of the Continuous Liquid Jet Core during Coaxial Air-Blast Atomisation

Measurements in an Acoustically Driven Coaxial Jet under Sub-, Near-, and Supercritical Conditions

Application of Proper Orthogonal Decomposition to the morphological analysis of confined co-axial jets of immiscible liquids with comparable densities

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