CFD Analysis of Intake Valve for Port Petrol Injection SI Engine
The air standard efficiency for SI engine is approximately 60% under full load condition but the actual brake thermal efficiency under full load condition is approximately 32.6% which is due to the various losses that occur. One of the primary lose is burning time loss which is approximately 4% and occur due to finite time combustion of the charge. This lose can be reduced to some extend by generation of a higher degree of swirl which will increase turbulence intensity with in the engine cylinder. The production of turbulence of higher intensity is one of the most important factors for stabilizing the ignition process, fast propagation of flame, especially in case of lean-burn combustion In general, two type of vortices are utilized in order to generated and preserve the turbulence flows efficiently. These vortices are usually known as swirl and tumble flows, which are organized rotations in the horizontal and vertical plane of the engine cylinder, respectively. They contribute to the improvement of engine performance. Hence, it is indispensable for the development of an ICE with high compression ratio to realize high turbulence intensity and lean burn combustion. Swirl can be generated during intake stroke as well as compression stroke of the engine. Intake generated swirl usually persists through the compression, combustion, and expansion stroke and it can greatly enhances the mixing of air and fuel to give a homogeneous mixture in the very short time. This is done by shaping and contouring the intake manifold, valve ports, and by use of shrouded intake valve. Keeping the above point in view, in this paper, an analysis is performed in a port fuel injection SI engine using computational fluid dynamic (CFD) code FLUENT to determine the level of intake swirl induced by poppet intake valve and its reduction along the length of the cylinder. From the study it was found that intensity of intake swirl reduces along the length of the engine cylinder.
