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There have been strong demands for complete combustion and eco-friendly engine for meeting the stringent emission norms. Homogenous charge formations within the cylinder is important to achieve complete combustion. This work deals with new cam shaft design of “NEGATIVE VALVE OVERLAP” (NVO) for achieving homogenous charge preparation within the cylinder. NVO study involves the early closure of exhaust valve which keeps delay between intake valve opening and exhaust valve closing, this allows more residual gas inside the cylinder. Based on the early closure of exhaust valve, two cam shaft profiles, 0° NVO and 10° NVO is selected. This study includes the 1D and 3D computational thermodynamic and fluid dynamic simulation of NVO in 3 cylinder, common rail direct injection (CRDI), turbo-charged intercooled diesel engine. The first part of the work involves the 1D thermodynamic analysis of NVO in which full throttle performance cases are simulated with the 1D computational model.

In heavy duty diesel engines, exhaust gas recirculation is often preferred choice to contain NOx emissions, in this a part of exhaust gas is tapped from exhaust manifold or later and recirculated to air intake pipe before intake manifold. Critical to such engines is the design of air intake pipe and intake manifold combination in view of proper exhaust gas mixing with intake air. The variation in exhaust gas mass fraction at each intake port should be as minimal as possible and this variation must be contained within +/− 10% band to have a minimal cylinder to cylinder variation of pollutants. Exhaust gas homogeneity for various intake configurations was studied using three-dimensional computational fluid dynamics for a 4 cylinder, 3.8 L, Diesel fuelled, common rail, turbocharged and intercooled heavy duty engine. Flow field was studied in the computational domain from the point before exhaust gas mixing till all the four intake ports.