Skip to Main content Skip to Navigation
New interface
Theses

Contribution à la modélisation Eulérienne de l'atomisation pour la pulvérisation agricole

Abstract : Pesticide environment pollution remains a significant social and environmental concern. During application, some of the pesticide may contaminate the environment (drift). The pollution reduction rests on the control of the drop size and velocity at the nozzle exit. The principal objective of this thesis is to develop an Eulerian approach in order to estimate the initial characteristics of the drops produced such as the size and the velocity at the nozzle exit. The Eulerian atomization model considers the two phase flow of a liquid and a gas as a turbulent single phase fluid flow with a variable mean density, varying between that of gas and that of spraying liquid. A transport equation for the mean liquid mass fraction allows to describe the dispersion of the liquid in the gas phase. Turbulence is modeled by Reynolds Stress Model (RSM) by solving the transport equations of each of the six components of the Reynolds tensor. In addition, a transport equation for the mean liquid/gas interface density is also considered. The mean liquid/gas interface density production which expresses the creation of the drops is function, on the one hand, of a large scale mean velocity gradient and, on the other hand, of small scale turbulence. The mean liquid/gas interface density destruction which expresses the coalescence of the drops takes into account the surface tension which is opposed to disintegration of liquid surface. The space evolution of the drop radius and velocity at the nozzle exit is described by coupling the equation of the mean liquid mass fraction and that of the mean liquid/gas interface density to those of the mass conservation, the momentum conservation and turbulence. The study is carried out by FLUENT V.12 using the User Defined Function (UDF) to adapt the code to our very particular injection conditions since the density ratio of liquid and gas is about 800. The results obtained by the model indicate the formation of a hollow conical spray made up of large droplets and the presence of a recirculation zone close to the spray axis made up of small droplets, in accordance with the experimentation. Comparison of the Sauter Mean Diameter (SMD) calculated by the model and measured in experiments by Phase Doppler Anemometry (PDA) shows good agreement.
Complete list of metadata

Cited literature [92 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-00663344
Contributor : Abdelhak Belhadef Connect in order to contact the contributor
Submitted on : Friday, January 27, 2012 - 11:15:48 AM
Last modification on : Wednesday, September 28, 2022 - 3:10:20 PM
Long-term archiving on: : Saturday, April 28, 2012 - 2:22:12 AM

Identifiers

  • HAL Id : tel-00663344, version 1

Citation

Abdelhak Belhadef. Contribution à la modélisation Eulérienne de l'atomisation pour la pulvérisation agricole. Mécanique des fluides [physics.class-ph]. Université de Provence - Aix-Marseille I, 2010. Français. ⟨NNT : ⟩. ⟨tel-00663344⟩

Share

Metrics

Record views

297

Files downloads

624