Simulation of in Cylinder Processes Accounting SDR Fluctuations for Better Predictions Using Hemispherical Piston

The research pertaining to modeling of engine processes is growing day by day where the important information about In-cylinder fluid motion, turbulence, temperature distribution, species concentration and many other characteristics are predicted. The In-cylinder gas flow is complex three dimensional, unsteady and turbulent and hence poses many problems and uncertainties in the theoretical predictions. The computational Fluid Dynamic models have gained momentum with the advent of high end computers for analysis of IC engine combustion process. The Computational Fluid Dynamic code considered at present is FLUENT. It is found that ignoring the effect of Scalar Dissipation Rate Fluctuations may cause inconsistency in predictions. Hence it is aimed to adopt Scalar Dissipation Rate Fluctuations by writing the User Defined Function (UDF) and appending it to existing code. The validation of the modified computer code is done by comparing the measured available data. It is a known fact that piston bowl configuration plays a vital role on the air motion and performance of the engine. In order to understand and demonstrate this effect, computations for spherical bowl configurations have been carried out. The results predicted with and without scalar dissipation rate fluctuations are compared to ascertain the need of inclusion of scalar dissipation rate fluctuations.