Search Results

An innovative Diffusive Air Jet (DAJ) Combustion Chamber concept has been introduced in the present work. The DAJ Combustion Chamber design is based on the study of rate of heat release (ROHR) curve and its correlation with emission generation. The objective is to lower the trade-off between NOx and soot without sacrificing fuel economy of Direct Injection (DI) diesel engine. DAJ Combustion Chamber modifies ROHR curve to the desired one so that it lowers engine out emissions. To study its effect, a large bore, six cylinder engine with mechanical fuel injection system has been used. Three dimensional simulation software is used for the model calibration of basic reentrant cavity. Local emissions and ROHR curve have been studied using reentrant cavity shape. It has been modified to DAJ Combustion Chamber using Air Jet Chambers (AJCs). AJCs are positioned in the three dimensional model in such a way that they affect local in-cylinder emissions.

In Direct Injection (DI) diesel engines, combustion gets affected by change in in-cylinder air motion and Fuel injection system characteristics. Computational Fluid Dynamics (CFD) based models give detailed insight into the combustion phenomena. The present work investigates the effect of different combustion chamber geometries and fuel injection system parameters on engine emissions and performance aiming to improve trade-off between NOx and smoke. AVL FIRE CFD software is used in this work. Research engine having 9 liter capacity of heavy duty application has been selected for the study. Seven hole injector is used with mechanical fuel injection system having 1000 bar maximum pressure capability. Inputs required to model complex combustion process in the AVL FIRE are derived from one dimensional engine simulation software AVL BOOST.

The stringent emission norms and increasing demand for engines with higher power density lead to an extensive investigation of parameters affecting combustion performance. Recent emission norms have forced the engine manufacturers to reduce the Particulate matter (PM) emissions along with other emissions substantially. In order to achieve lo PM emissions the lubrication oil consumption need to be controlled by optimizing piston group design with low liner bore distortion. Bore Distortion is the deviation of actual profile from perfect circular profile at any plane perpendicular to axis of cylinder. Liner bore distortion in engines causes' number of problems like deterioration of piston ring performance, liner-ring conformability issues, high lubricating oil consumption and emissions.