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Two stage turbo charging provides a suitable method to achieve a significant increase of the boost level, as well as a wider operating range for a diesel engine. This paper describes detailed and easily applicable method for two stage turbocharger matching for constant speed engine, in view of finding an optimal combination of turbochargers - low and high pressure ones. It also describes technique that can be used for optimizing solution with better fuel consumption and boosting together with satisfying of all given constraints such as maximum before turbine and compressor out temperatures, maximum turbocharger speed, peak cylinder pressures and smoke limit. This paper presents evaluation of potential for two stage turbocharger for power generation application by simulation and then experimental 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.

To meet stringent emission norms with internal engine measures, design of piston cavity geometry perform a defining role in air motion, fuel air mixing, combustion and emission formation. A study is performed with the objective to have a better tradeoff between NOx, PM and fuel consumption for a Medium duty, constant speed diesel engine operated with Mechanical fuel injection system. Through simulations in 3D CFD tool the effect of piston cavity geometry on performance and emission of diesel engine is investigated and then validated with actual experimentation. In this exercise efforts are made to reduce emissions in a direct injection diesel engine by changing the piston cavity geometry. The piston cavity geometry and dimensions like torus radius, pip region, cavity lip area, and impingement area have an effect on emission formation. The target was to deliberately split the fuel spray and have a better utilization of available air.