Investigation on Small Rotary Engine In-cylinder Turbulent Flow Based on Large Eddy Simulation

In this paper, large eddy simulation (LES) is adopted to investigate the 3D flow characteristics of a small rotary engine, including turbulence fluctuation, turbulent kinetic energy and coherent structure. Three sets of conclusions based on computational results are obtained. First, by using LES coupled with Q-criterion, large scale coherent structures are identified well. It is found that high intensity vortices are distributed in the leading and trailing of the chamber in the intake process and move from the central to the trailing region in the compression process. Second, fluctuating velocities in cross section perpendicular to rotor surface shows drastic fluctuation in normal direction. In these cross sections, fluctuating velocities near the central region are relative higher. Velocities in cross sections parallel to the covers have no obvious fluctuation. Third, at the period from the intake open to top dead center, subgrid turbulent energy and mean gas velocity occurs two obvious peaks, which are related to the intake energy and break of large scale vortices, respectively.