Optimization of In-Cylinder Flow and Swirl Generation Analysis for a Naturally Aspirated Diesel Genset Engine for Emission Reduction through Intake Port Design

Engine in-cylinder flow structure governs the combustion process and directly influences emission formation and fuel consumption at the source. In naturally aspirated DI diesel engine, combustion process coupled with low pressure mechanical fuel injection systems set different requirements for inlet port performance. In-cylinder swirl needs to be optimized for efficient combustion to meet emission levels and fuel consumption targets. Thus, intake port design optimization process becomes a vital requirement.

In the present paper intake port design optimization is carried out for single cylinder naturally aspirated engine using mechanical fuel injection systems. The objective is to investigate in-cylinder flow field developed by intake port designs, study the effects of geometrical details of various port cross sections on flow velocity and pressure fields and establish a relationship with intake port performance parameters i.e. swirl and flow coefficient. CFD analysis is carried out for port performance study at various valve lift positions. The design variants are experimentally validated on steady state test rig using paddle wheel principle. Further, the impact of these new intake port designs on single cylinder diesel engine emissions and performance is evaluated. Engine out emission levels are achieved at a very good margin along with improved fuel consumption. Thus the focus is given to create design guidelines for optimizing intake port performance which in turn required for efficient combustion system development and emission reduction.