A study of turbulence phenomenas in simplified flow situations of interest for diesel combustion development
Examensarbete för masterexamen
The interest to investigate real ame propagation in diesel engines lead to this master thesis project where OpenFOAM version 1:7:1 (Open Field Operations And Manipulations) has been used to simulate an equivalent high speed diesel jet entering a combustion chamber. In real situations, the fuel enters the domain in liquid phase, then evaporates into a gas. In this work, the jet enters the domain as pure gas phase, i.e. it is treated as if the evaporation occurs instantaneously. When no phase transformation occurs it will be referred to as an equivalent gas jet. Both standard and tuned versions of the k-turbulence model have been used in order to validate the similarity of the simulated fuel penetration curves that were compared with the experiments at Chalmers HP/HT combustion chamber and data presented by Siebers and Naber. After validation of the equivalent gas jet, Large eddy simulations (LES) is used, in order to enhance the level of details in the turbulent gas jet. The main purpose of this project is to be able to analyze the turbulent quantities and structures of the ow, which cannot be done using RANS models. In simulations of transient phenomenas, such as diesel sprays, it is particularly important to get an instantaneous view of the flow. The simulation study starts with a simple flow situation and then the complexity gradually increases. Three different geometries have been used. The first one is a free volume, without any interference with the walls and the other two have a at plate and a curved wall mounted, respectively.
Energi , Hållbar utveckling , Transport , Strömningsmekanik , Energy , Sustainable Development , Transport , Fluid mechanics