CFD Analysis of Swirl Generation in Single Cylinder Diesel Engine and the Study of the Affecting Parameters

摘要

Swirl in the Diesel Engine is known to be an important parameter that affects the mixing of fuel jets, emissions and overall engine performance. Swirl can be produced by the variation in the flow pattern of charge inside the cylinder. The purpose of this project is to re-design the inlet port of an internal combustion engine in order to enhance the production of turbulence by swirl. A good swirl promotes fast combustion and improves the thermal efficiency. The engine should run at low speeds, in order to have low mechanical losses but the combustion should be fast enabling good efficiency. The first thing was to generate a CAD geometry. Then CFD software meshes the geometry in the design by using a volume mesh. At last it calculates the flow within the engine by using a suitable turbulent model. Initially the current geometry was tested and proved to create low swirl, so the geometry was changed several times until reaching a good result in terms of generated swirl. The test includes the just steady flow, where the air enters the inlet port and leaves the bottom of the cylinder continuously. The flow within the cylinder is examined at specific sections, namely at various heights of the cylinder (horizontal sections) and path lines were evaluated. The flow is analyzed for different valve lifts and boundary conditions.