March 6 - 8, 2017 | Berlin
LEADING ENGINEERING SIMULATION CONFERENCE
With increasingly strict emissions legislation, an alternative to conventional fuel is natural gas. It is available in abundance, cheaper than Diesel and gasoline and most importantly, releases less greenhouse gases (CO2) during combustion due to higher H/C ratio. The dual fuel engine with natural gas as primary fuel and Diesel as secondary fuel for pilot injection is a promising concept for future reciprocating engines. However, due to slow flame propagation in leaner (Φ~0.6) fuel/air ratios, combustion remains incomplete releasing CO, formaldehyde, and unburnt CH4. One way to enhance flame propagation is to increase turbulent kinetic energy (TKE) near top dead center by optimizing piston bowl geometry and squish height. In this investigation, different piston bowl geometries and squish heights were modelled and TKE was investigated numerically with Star CD es-ice 4.26. For simulation, 1.4 million cells (at bottom dead center) grid was selected after grid independence test. Also, flame propagation was investigated for these geometric variations using the Progress Variable Model- Multi Fuel (PVM-MF) combustion model. The results show that increase TKE enhanced flame propagation in the combustion cylinder. In addition, the data show influence of various piston bowl geometric dimensions on in-cylinder flow and hence TKE.