On the break-up times and lengths of diesel sprays

Yule, A. J.; Filipović, Ivan

doi:10.1016/0142-727x(92)90028-8

Cited by 27 publications

(9 citation statements)

References 5 publications

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“…(14). The molar flux of droplet's vapour corresponds to the difference in the concentration of vapour between the droplet surface and bulk gas [19].…”

Section: Methodsmentioning

confidence: 99%

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Modelling of spray evaporation and penetration for alternative fuels

Azami

Savill

2016

Fuel

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a b s t r a c tThe focus of this work is on the modelling of evaporation and spray penetration for alternative fuels. The extension model approach is presented and validated for alternative fuels, namely, Kerosene (KE), Ethanol (ETH), Methanol (MTH), Microalgae biofuel (MA), Jatropha biofuel (JA), and Camelina biofuel (CA). The results for atomization and spray penetration are shown in a time variant condition. Comparisons have been made to visualize the transient behaviour of these fuels. The vapour pressure tendencies are revealed to have significant effects on the transient shape of the evaporation process. In a given time frame, ethanol fuel exhibits the highest evaporation rate and followed by methanol, other biofuels and kerosene. Ethanol also propagates the farthest distance and followed by methanol and kerosene. However, all biofuels have a shorter penetration length in the given time. These give penalty costs to biofuels emissions formation. The influences of initial conditions such as temperature and droplet velocity are also explored numerically. High initial temperature and velocity could accelerate evaporation rate. However, high initial temperature has resulted in low penetration length while high initial velocity produces contrasting results.

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“…(14). The molar flux of droplet's vapour corresponds to the difference in the concentration of vapour between the droplet surface and bulk gas [19].…”

Section: Methodsmentioning

confidence: 99%

“…Yule and Filipovic [14] have predicted the break-up length which refers to the distance of fully atomized droplet which is equivalent to 35% of the penetration length. Later, Ryu et al [15] showed that the spray penetration length is directly proportional to the power of ¼ of back pressure.…”

Section: Literature Reviewmentioning

confidence: 99%

Modelling of spray evaporation and penetration for alternative fuels

Azami

Savill

2016

Fuel

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“…It is particularly useful to simplify these initial and boundary conditions while maintaining realism in important parameters. This approach has been used in previous experimental work at the University of Manchester Institute of Science and Technology (UMIST) (1,2) and elsewhere, for example reference (3), which has investigated the 'free' diesel sprays, before impaction, with variations of the density, velocity and temperature of the surrounding gas. This has been achieved using high-pressure chambers and wind tunnels which must be specially designed to model the in-cylinder conditions, for example gas pressure P, typically 5 MPa; gas temperature up to 1100 K; and gas swirl or cross-flow velocity W, up to 20 m/s.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Boundary Conditions on the Downstream Penetration of Pulsed Sprays After Impaction on a Flat Surface

Yule

Mirza

1996

Proceedings of the Institution of Mechanical Engineers, Part D:

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An experimental study has been conducted of the wall sprays produced afer impaction on a j a t surface by the pulsed sprayfrom a single hole nozzle. The experiments are of relevance to direct injection diesel engines and they extend the range of boundary conditions covered in previous work, with variation of gas density, spray wall angle, gas cross-Jlow velocity and cross-Jlow turbulence level. The initial and boundary conditions are documented to provide a database which is suitable for computational Puid dynamics (CFD) model validation of an important aspect of diesel engine in-chamber Jlow. Previous work in the area is described and published empirical correlations are reviewed. The measurements of wall spray penetration as a function of time are presented and described and a correlation equation is proposed whichJits the data with good accuracy.diesel engines, sprays, fuel injectors, wall impaction NOTATION gation of the characteristics of diesel fuel sprays. J . Mech. Engng SOC., Japan, 1980,15,57-64. Coghe, A. and Cossali, G. E. Experimental analysis of wall-spray structure by laser-Doppler techniques. Proc. ILASS-92, 1992, 97-103 (Shell, Amsterdam). 2~10, J. R. and Cbigier, N. Impinging diesel spray dynamics. Atomization and Sprays, 1991,1,303-318. Yule, A. J. and Awl, S. M. Cyclic variations in diesel sprays. Fuel J., 1 9 8 9 , s 1558-1564. Mum, M. R. Studies of diesel sprays with cross-flows and solid boundaries. PhD thesis, sprays produced by a diesel injector: further details of spray structure. To be submitted to Roc. Instn Mech. Engrs, Part D.

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“…There is very little experimental data giving the break-up length of a jet as it is being injected, but the experiments of [4] and [5] give steady jet break-up lengths for axisymmetric jets of the order of 80 to 300 nozzle radii, so in §3 we fix our break-up time (by fixing the parameter ) so that we have break-up lengths of this approximate order. Although we will have numerical timing restrictions stopping us from having too long a break-up length, this won't affect the unsteady/quasi-steady jet comparison in this paper.…”

Section: Formulationmentioning

confidence: 99%

“…The liquid fuel is injected into the combustion chamber through an injector (which can have multiple holes) where it breaks up into liquid sheets, ligaments and droplets before evaporating and burning up in the autoignition and combustion processes. From this process, one important piece of information is the 'break-up length' of the jet, which is the distance from the nozzle to the point at which liquid sheets, ligaments and droplets begin to form [4,5]. The calculation of this length and the overall modeling of this process is very important to the modelling of the processes in Diesel engines using CFD codes [6].…”

Section: Introductionmentioning

confidence: 99%

Wave packet analysis and break-up length calculations for an accelerating planar liquid jet

et al. 2012

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This paper examines the process of transition to turbulence within an accelerating planar liquid jet. By calculating the propagation and spatial evolution of disturbance wave packets generated at a nozzle where the jet emerges, we are able to estimate break-up lengths and break-up times for different magnitudes of acceleration and different liquid to air density ratios. This study uses a basic jet velocity profile which has shear layers in both the air and the liquid either side of the fluid interface. The shear layers are constructed as functions of velocity which behave in line with our CFD simulations of injecting Diesel jets. The non-dimensional velocity of the jet along the jet centre-line axis is assumed to take the form V (t) = tanh(at) where the parameter a determines the magnitude of the acceleration. We compare the fully unsteady results obtained by solving the unsteady Rayleigh equation, to those of a quasi-steady jet to determine when the unsteady effects are significant, and if the jet can be regarded as quasi-steady in typical operating conditions for Diesel engines.For a heavy fluid injecting into a lighter fluid (density ratio ρ air /ρ jet = q < 1) it is found that unsteady effects are mainly significant at early injection times where the jet velocity profile is changing fastest. When the shear layers in the jet thin with time, the unsteady effects cause the growth rate of the wave packet to be smaller than the corresponding quasi-steady jet, while for thickening shear layers the unsteady growth rate is larger than that of the quasi-steady jet. For large accelerations (large a) the unsteady effect remains at later times but its effect on 1 Corresponding author: M.Turner@surrey.ac.uk 2 Present address: Department of Mathematics, University of Surrey, Guildford, Surrey GU2 7XH UK 3 Present address: ANSYS UK, Ltd., 97 Milton Park, Abingdon, Oxfordshire OX14 4RY UK 21 November 2011 the growth rate of the wave packet decreases as the time after injection increases. As the rate of acceleration is reduced, the range of velocity values that the jet can be considered as quasi-steady increases until eventually the whole jet can be considered quasi-steady. For a homogeneous jet (q = 1) the range of values of a for which the jet can be considered completely quasi-steady increases to larger values of a.Finally we investigate approximating the wave packet break-up length calculations with a method which follows the most unstable disturbance wave as the jet accelerates. This approach is similar to that used in CFD simulations as it greatly reduces computational time. We investigate whether or not this is a good approximation for the parameter values typical used Diesel engines.

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On the break-up times and lengths of diesel sprays

Cited by 27 publications

References 5 publications

Modelling of spray evaporation and penetration for alternative fuels

Modelling of spray evaporation and penetration for alternative fuels

The Effect of Boundary Conditions on the Downstream Penetration of Pulsed Sprays After Impaction on a Flat Surface

Wave packet analysis and break-up length calculations for an accelerating planar liquid jet

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