Knowledge of the flow phenomena inside the cylinder is necessary for optimum design of the intake port and the piston cavity configurations. Recent trends in direct injection diesel engines have increased the need for clear understanding of the flow field, especially the swirl characteristics. The swirl flow is an essential parameter which affect the air fuel mixing, combustion efficiency and therefore the engine performance. The purpose of this study is to investigate the combustion, emission, spray and flow field phenomena of D I diesel engine is to come up with the geometrical shape of a port and valve or valves that produce the optimum swirl ratio. The variation of steady state swirl with valve lift for the helical port of a DI diesel engine are simulated and studied using Computational Fluid Dynamics with experimental validation.

Steady flow rig experiments are most widely used to evaluate the swirl ratio of an intake port design. The three dimensional developing flow patterns may be needed throughout the compression and combustion stroke to understand the various experimental results. Flow is simulated by solving governing equations, viz., conservation of mass and momentum using the simple - algorithm. Turbulence has been modeled by standard k model with standard wall treatment. The predictive accuracy of the calculation method is compared with detailed mass flow rate and paddle rpm measurements. The results are in good agreement with experimental results and clearly predict the under predictability of the paddle swirl meter in lower lifts.

Emission standards, which demand large reduction in NO and PM emission, require a more comprehensive study of all x elements that contribute to emission formulation. The combustion chamber is subject of research and development in a effort to achieve optimized combustion system. In particular, intake port fluid dynamics contribute to the fuel air mixing which in turn is the most important parameter for the control of fuel burning rate for diesel engines. The intake port fluid dynamics also significantly affects ignition delay, the magnitude and timing of the diffusion burn, the magnitude of the premixed burn and Emission of nitrous oxide and soot. In this study, the numerical simulation of the helical intake port for two-valve DI Diesel engines is discussed with experimental validation. The improvement of the design according to the stringent emission norms and the variation of swirl generation capacity of the port are also studied.