Experimental and Numerical Investigation of Injection Rate Shaping in a Small-Bore Direct-Injection Diesel Engine

This study evaluates the Boot and the Top-hat injection rate shapes at a single high-load point of a single cylinder small-bore direct-injection (DI) Diesel engine using experimental and multidimensional engine simulations results. In experiments, injection rate shapes were generated using CoraRS injector. The simulations were performed using Representative Interactive Flamelet (RIF) model. First, model predictions of cylinder pressure and exhaust emissions are validated against experimental data. The trend seen in heat release rate is primarily attributed to the rate of fuel evaporation. A new method – Two-part analysis – is then used to explain the results of simulations. The analysis shows that lower exhaust Soot and CO emissions in Boot shape are due to their faster oxidation in squish region.