Numerical Analysis of the Effects of Swirl Ratio on the Performance of Diesel Engine Fueled with N-Butanol–Diesel Blends

Abstract

The use of renewable alternative fuels in diesel engines has grown recently. In order to study the effects of different swirl ratios (SRs) on the performance of a diesel engine fueled with n-butanol–diesel blends, the combustion process of a 186FA diesel engine with pure diesel, 20% n-butanol and 80% diesel fuel by volume (BU20) and 30% n-butanol and 70% diesel fuel by volume (B30) fuel at five swirl ratios was simulated using AVL Fire software. The simulation model was validated by comparing the calculation results and experimental results with the in-cylinder pressure, heat release rate, and emissions of soot and nitrogen oxides (NOx). This paper analyzes the effects of the different swirl ratios on combustion and emissions characteristics and on the concentration field in the cylinder. The results show that soot generation for the three kinds of fuels gradually decreases with the increase of the swirl ratio (SR). For BU20, the soot mass fraction of SR0.2 was 219×10−6, and the largest decline in soot generation was 82%. NO emissions first increased and then decreased with the increase of the swirl ratio for BU20 and BU30. For BU20, the NO formation for SR0.2 was 620×10−6, and when the swirl ratio was 1.8, NO formation reached its highest level of 905×10−6, increasing by 46%. As a compromise between enhancing power output and reducing emissions, a swirl ratio of 1 was optimal for pure diesel and a swirl ratio of 3.4 was optimal for BU20 and BU30.