CFD analysis of nozzle effect on jet formation
Abstract: This project is concerned with CFD simulations of jets issued from elliptical nozzles. The investigated jet flow in this project is turbulent flow emanating from microscopic nozzles into a combustion chamber. Jet flows are very common in engineering, medical and environmental applications and are for instance used in fuel injection systems, spray painting and drying. Jet flow devices are also very common in applications such as cutting, hydraulic drilling, cooling and heating. A better understanding of the flow phenomenons in jet flows are required in order to make these devices function and perform in a more efficient way. The performance of diesel engines is strongly affected by the fuel spray, atomization and in turn the mixing process. This depends ultimately on the dimensions and geometry of the nozzle. The purpose of this project was therefore to investigate different elliptical nozzle geometries which also was compared to a conventional circular nozzle. Three dimensional simulations have been performed to investigate flow quantities in the turbulent Reynold’s Averaged Navier Stokes and Large Eddy Simulation models in a single phase flow. Simulation of a two-phase flow with the Large Eddy Simulation model was also performed to investigate the inception and development of cavitation. The Volume of Fluid approach was used to describe the twophase flow and Rayleigh-Plesset equation to solve bubble dynamics.The mathematical models regarding those in single phase flow have been solved in the CFD software ANSYS FLUENT, while those in two-phase flow have been solved in the open source C++ toolbox OpenFOAM 2.0.0.
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