Modelling Flow Inside a Gasoline Engine

The in-cylinder air flow pattern in the combustion chamber of an internal combustion engine has a significant impact on engine performance and emission characteristics. It also affects engine noise, harshness, and durability. Inducting more air inside the combustion chamber at a sufficient turbulence level has always been the main concern for engine designers. In-cylinder charge motion is highly unsteady and non-uniform. It is very complex to visualize and understand it through mere experimental techniques available today. Nowadays, multi-dimensional computational fluid dynamics (CFD) has become a widely accepted and indispensable tool in the analysis of in-cylinder flows, combustion, emission prediction, and engine performance. The outcomes of CFD analysis are subject to the accurate modelling of engine geometry, mesh quality, and selection of sub-models to replicate the physics. The proper input boundary conditions also play a vital role in the accuracy of CFD simulations. The chapter presents insights on 1- and 3-dimensional modelling of the in-cylinder phenomenon in spark ignition engines. The general techniques and governing equations behind the CFD sub-models have been explained. The effects of combustion chamber shape, piston shape, fuel injection, valve lift, and water injection are thoroughly presented.