Experimental and numerical study on the influence of intake swirl on fuel spray and in-cylinder combustion characteristics on large bore diesel engine

In the present study, the numerical simulation of the performance of fuel injection and spray atomization on diesel engine combustion was conducted, which was validated against fuel injection test, spray test and single cylinder diesel engine test. Thus, the effect of the intake swirl on the fuel spray and diesel engine combustion performance was explored. Quantitative analysis of the characteristics of fuel-air mixing and combustion characteristics under different swirl ratio was given. It was found that the spray atomization and fuel-air mixing begins from the front of fuel beam which has deflection due to the presence of the intake swirl. The function of swirl is to accelerate the mixing and diffusion speed of fuel, thus promoting the combustion process in cylinder. Meanwhile, the NO and Soot emissions were quite sensitive to the swirl ratio, which leads higher NO but lower Soot as the swirl ratio is increased. In addition, the performance of varied swirl ratio on spray penetration and spray angle was well captured by numerical studies in the paper. Consequently, this study reveals the influence of different swirl ratio on the fuel spray performance, output power and fuel consumption, thus exploring the influence of inlet swirl of the controllable swirl diesel engine on the fuel atomization behavior as well as dynamic performance, and verifying the accuracy of the simulation results.