Combustion performance and energy distributions in a new multi-swirl combustion system

Previous research has demonstrated that the separated swirl combustion system (SSCS) based on double swirl and TCD combustion chamber improves direct-injection diesel engine combustion performance. A new multi-swirl combustion system based on lateral swirl and TCD combustion chamber (MSCS-LT) was proposed in this study. Experimental research was performed using single-cylinder diesel engine to study MSCS-LT and SSCS combustion performance and energy distribution characteristics. Simulation research was performed to reveal the influence mechanisms of the combustion chamber structure on in-cylinder fuel-air mixing quality and heated part surface temperatures. Experimental results show that MSCS-LT provides better combustion performance and lower energy losses under various working conditions than SSCS, especially at high loads and low excess air coefficients. Simulation results show that MSCS-LT enhances fuel diffusion in the axial and circumferential directions, producing better fuel-air mixing quality. Since most of the fuel is kept in the combustion chamber, direct contact between the high-temperature gases and heated parts is avoided. However, in SSCS, the interference of adjacent fuel sprays causes the accumulation of the rich fuel-air mixture, deteriorating the fuel-air mixing quality. Meanwhile, the excessive injection angle causes direct contact between the high-temperature gases and the cylinder head as well as the cylinder liner, resulting in higher surface temperatures.