Numerical Investigation of In-Cylinder Tumble/Swirl Flow on Mixing, Turbulence, and Combustion of Methane in SI Engine

In the present work, the in-cylinder tumble/swirl flow and its effect on the homogeneity, turbulence, and combustion of methane are investigated in a canted valve engine using ANSYS. The study is focused on the impact of initial swirl and tumble on the charge preparation, turbulent kinetic energy, and combustion of methane. The flow simulation was performed in ANSYS using hybrid mesh for cold flow simulation to study the tumble/swirl flow variation. For combustion simulation, a 2D axisymmetric model was used with an initial swirl and tumble ratio for studying the effect on premixed combustion. The flow simulation was performed for suction and compression to see the variation in the swirl and tumble with crank position and engine speed. The combustion simulation was performed only for compression and power stroke to save the computation time. The results depict that the flow inside the cylinder plays a significant role in the preparation of a homogeneous charge. Tumble/swirl mainly affects the turbulence as the tumble increases, and the peak combustion pressure is shifted few crank angle degrees earlier, which leads to higher dissipation. Turbulent kinetic energy increases rapidly with an increase in swirl and tumble because the disturbance gets amplified with higher flow variation. Thus, more energy is added to the flow at TDC because of increased vortices in the flow due to breakdown in tumble, which leads to proper mixing and smooth combustion.