Eulerian atomization modeling of a pressure-atomized spray for sprinkler irrigation

Stevenin, C.; Vallet, A.; Tomas, Séverine; Amielh, Muriel; Anselmet, Fabien

doi:10.1016/j.ijheatfluidflow.2015.11.010

Cited by 21 publications

(14 citation statements)

References 18 publications

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“…However, at low Weber and droplet Reynolds numbers (respectively around 0.1 and 0.5), anisotropy coefficient is larger, around 0.25 ( El-Asrag and Braun, 2015 ). In that case, the spray is quickly dispersed into small droplets ( x / d nozzle < 10) when, in our spray, the liquid core reaches x/d nozzle = 210 ( Stevenin et al, 2016 ). This observation is also corroborated by Sahu et al (2014) who report that the droplet velocity fluctuations are isotropic close to the spray axis with an increase in anisotropy towards the spray edge (but that does not exceed 0.8 which is still relatively large in comparison with our data).…”

Section: Velocimetry Of Droplets By Size Classmentioning

confidence: 77%

“…Measurements highlight considerable anisotropy of droplet turbulence in relation to this reduction in the jet spreading rate. Estimations of the constant C μ show values lower than those classically observed, leading us to consider choosing different constants for future modeling work ( Stevenin et al, 2016 ). Furthermore, the data collected indicate that the dynamics of the droplets is strongly influenced by their size, underlining the importance of carrying out measurements of velocities and droplet size simultaneously to analyze this type of flow.…”

Section: Resultsmentioning

confidence: 98%

“…As a consequence, the jets involved in sprinkler irrigation are very different from usual sprays. On the contrary to usual liquid sprays, sprinkler jets have a very long core of liquid, which can reach up to 210 nozzle diameters ( Stevenin et al, 2016 ). The surface of this liquid core is very turbulent and on it are present very thin liquid ligaments, which give raise to the first small droplets.…”

Section: Introductionmentioning

confidence: 95%

See 2 more Smart Citations

Flow characteristics of a large-size pressure-atomized spray using DTV

Stevenin

Tomas

Vallet³

et al. 2016

International Journal of Multiphase Flow

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Section: Velocimetry Of Droplets By Size Classmentioning

confidence: 77%

Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 95%

See 1 more Smart Citation

Flow characteristics of a large-size pressure-atomized spray using DTV

Stevenin

Tomas

Vallet³

et al. 2016

International Journal of Multiphase Flow

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“…Very small particles (i.e., nanometric and micrometric) and pathogens manage to travel for many kilometers before readily infiltrating human lungs (Donaldson et al 1982;Papke and Ward 2004). Size distribution is the outcome of the combination of numerous parameters such as the weather conditions (temperature, relative humidity, and wind and solar radiation), sprinkler technology, and atomization process (Gantzer et al 1998;Hogan et al 2005;Dumouchel 2008;Stevenin et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Assessment of Airborne Transport of Potential Contaminants in a Wind Tunnel

Cornacchia

Tomas

Douzals

et al. 2020

J. Irrig. Drain Eng.

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The reuse of treated wastewater (TWW) for sprinkler irrigation could potentially diffuse pathogen-containing droplets off the application area. Wind and other unfavorable climatic factors enhance irrigation drift and bioaerosol dispersion, exposing humans to potentially severe health risks including the spread of diseases. Few studies have quantified bioaerosols during both spraying and airborne transport phases. Studies of effective sampling strategies to better qualify the dispersion process are also required. This paper presents experiments conducted in a wind tunnel for a deeper understanding of the effects of wind and temperature on pathogen or contaminant airborne dispersal and transport. It is the first time that passive collectors [polyvinyl chloride (PVC) lines] and active samplers (AGI-4 impinger) have been compared under analogous wind conditions using a fluorescent tracer. Droplet-size distribution was also investigated at 12 m from the boom with a NanoMoudi 122-NR cascade impactor in increasing wind conditions from 1 to 3 m s −1. PVC lines return a detailed evolution of the sprayed volume within a short range from the boom and for concentrated fluxes. Transport assessment of PVC lines indicates that transport and permanently airborne condition of the spray notably grow with increasing wind, resulting in a more compact and concentrated plume; mean transport increases from 0.13 to 1.18 L h −1 m −2 at 7.7 m from the nozzle as the wind velocity increases from 1 to 3 m s −1. AGI-4 appears more suitable to assess finely aerosolized conditions because of its greater sensitivity compared to PVC lines as shown for sample values less than 1 L h −1 m −2. The comparison between the AGI-4 and PVC lines shows higher values of recovery for the active samplers compared to the PVC lines. The total volume collected by the impingers was 2.93% of the sprayed volume, approximately twice that collected by PVC lines under analogous conditions, even though their sampling surface was only 1.54% that of PVC lines. Droplet-size distributions from the cascade impactor denote a median volume diameter from 1.1 to 2 μm, for the nozzle type used, and a relevant reduction in recovery at stronger wind velocities. An empirical relation time of flight is proposed as a first step in developing decision models that can be used to make sprinkler irrigation safe and to define standards for TWW reuse in agricultural practices (e.g., safe distance of application depending upon wind conditions and droplet-size distribution).

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“…Compared to the present study, past models either lack a description of the density or liquid fraction of the spray, make unrealistic assumptions or introduce parameters unavailable experimentally. There are also widely used numerical models based on turbulence modelling for jets, like the one by [7] used in CFD programs like Star-CD, KIVA-3V, Ansys Fluent, as well as open source codes like OpenFOAM [8]. The present work is mainly concerned with developing an analytical or nearly analytical model with the advantage of producing closed expressions and/or fast calculations.…”

Section: Introductionmentioning

confidence: 99%

Mathematical models for turbulent round jets based on “ideal” and “lossy” conservation of mass and energy

Franco

Fukumoto

2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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We propose mathematical models for turbulent round atomized liquid jets that describe its dynamics in a simple but comprehensive manner with the apex angle of the cone being the main disposable parameter. The basic assumptions are that (i) the jet is statistically stationary and that (ii) it can be approximated by a mixture of two fluids with the phases in local dynamic equilibrium, or so-called locally homogeneous flow (LHF). The models differ in their particular balance of explanatory capability and precision. To derive them we impose partial conservation of the initial mass and energy fluxes, introducing loss factors again as disposable parameters. Depending on each model, the equations admit explicit or implicit analytical solutions or a numerical solution in the discretized model case. The described variables are the the two-phase fluid's composite density and velocity, both as functions of the distance from the nozzle, from which the dynamic pressure is calculated. Keywords Mathematical Modeling, Two Phase Fluid, Locally Homogeneous Flow, Statistically Stationary State IntroductionThe range of applications involving atomizing liquid jets forming two-phase fluid flows is still large. The complexity of the atomizing process, involving numerous physical phenomena and many variables, ranging from the conditions inside the nozzle (or some generating source) to the interaction between the atomization process and the environment into which the jet is penetrating, all account for numerous challenges in physical and mathematical modeling. Notwithstanding, several such models have been attempted to describe different aspects of the jets in this regime. For example, differential equations for a fuel jet's tip penetration distance as a function of time [1, 2, 3]; models for the gas entrainment rate in a full-cone spray [4]; and a one-dimensional model for the induced air velocity in sprays [5]. None of these models is sufficient by itself as explained below. In this study we propose three original related 1D mathematical models, so-called "energy jet models", for the macroscopic dynamics of a turbulent round jet ensuing from a circular nozzle into a stagnant fluid. This kind of jets serves as a basis for many industrial processes in modern manufacturing industry [6]. An advantage of our models over other analytical 1D models is that the simplest case of the "ideal energy jet" has a single experimentally measurable parameter (the jet half-angle θ) while it maintains reasonable predictive power and gives theoretical understanding that allows it to analytically calculate other physical quantities of interest. Moreover, the herein reported other extended models class, the "lossy energy jet" models, apply an energy conservation approach with simple turbulence and energy dissipation models, resulting in increased accuracy. Compared to the present study, past models either lack a description of the density or liquid fraction of the spray, make unrealistic assumptions or introduce parameters unavailable experimentally...

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Eulerian atomization modeling of a pressure-atomized spray for sprinkler irrigation

Cited by 21 publications

References 18 publications

Flow characteristics of a large-size pressure-atomized spray using DTV

Flow characteristics of a large-size pressure-atomized spray using DTV

Assessment of Airborne Transport of Potential Contaminants in a Wind Tunnel

Mathematical models for turbulent round jets based on “ideal” and “lossy” conservation of mass and energy

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