Development of a Parametric Model for Burn Rate Estimation in Direct Injection Diesel Engine

In internal combustion engines, rate of fuel burning known as burn rate is a simplified representation of complex in-cylinder combustion process. It is considered as a prime input especially in 1D simulation tool for all important thermodynamic studies. A novel parametric model for prediction of burn rate in heavy duty Direct Injection (DI) diesel engine has been introduced in the present work. A wide range of experimental data with more focus on higher load points with different in-cylinder combustion characteristics is considered and burn rates have been generated using measured pressure trace. Generated burn rates have been studied over different phases of combustion. These burn rate shapes have been analyzed to understand the effect of fuel injection system, air management subsystem parameters along with in-cylinder conditions on combustion. Different mathematical modelling approaches for burn rate approximation like Wiebe function have been studied. Burn rates generated using experimental data have been reproduced using a newly developed mathematical modelling approach. Part of diffusion and late combustion phase has been captured by a unique correlation. This mathematical model comprises different shape factors. Parameters from different subsystems like start of injection, rail pressure, lambda, compression ratio and other parameters which are having influence on combustion characteristic are selected. Extensive parametric study has been done to check the dependency of these parameters on the shape factors of the mathematical model. A parametric model has been developed from this study. This modelling approach can be used for the burn rate predictions where experimental data is limited and burn rate shape can be estimated from different subsystem inputs.