RETRACTED: Numerical investigation of the effect of swirl number on performance, combustion, and emissions characteristics in a converted heavy-duty natural gas engine

Abstract

In this study, the performance, combustion characteristics, and emission behavior of a diesel engine converted to a spark ignition engine running on natural gas were investigated. The initial diesel injection time of 719.5 CAD (Crank Angle Degree) was recognized as the spark ignition time, and no optimization work was done. RANS (Reynolds Averaged Navier-Stokes) k-e turbulence model, reduced methane chemical kinetic mechanism, and G-equation combustion model were all used in the numerical analysis. The studies were performed at full load, 2300 rpm, 17.5:1 compression ratio, constant spark ignition time, and 7 different swirl ratios. As a result, the homogeneous-air fuel mixture formed in the cylinder due to the the swirl ratio rising, and the increased combustion performance dominated the heat loss due to the rise in the swirl number, thereby improving the performance. However, with the increase of in-cylinder temperatures, NOX emissions increased. Following conversion, soot, carbon monoxide (CO), and unburned hydrocarbon (UHC) emissions levels remained practically extremely low. As the swirl ratio increased from 1.2 to 2.4, the GIP (Gross Indicated Power), IMEP (Indicated Mean Effective Pressure), ITE (Indicated Thermal Efficiency), and MPRR (Maximum Pressure Rise Rate) values increased by 4.1, 4.13, 3.98, 102.2%, while the GISFC (Gross Indicated Specific Fuel Consumption) value improved by 3.97%.