Study on vortex characteristics and velocity distribution in small rotary engine

In this paper, vortex characteristics and velocity distribution in the chamber region were studied by numerical method. The three-dimensional moving grid and Improved Delayed Detached Eddy Simulation Shear-Stress Transport model which is a hybrid RANS/LES model were used to predict evolution processes of streamlines and velocity change in small rotary engine. The simulation results show that vortex has always existed in intake process and has gone through three stages, including generation, brakedown, regeneration. The generation is mainly due to intake charge. The brakedown and regeneration is because of the shear and friction of the rotor face. Vortex radius in the leading gradually increases and in the trailing decreases in intake stroke from 490 degrees C BTDC to 390 degrees C BTDC. And the position of vortex core in the leading has no obvious change and in the trailing moves towards the trailing apex along the rotor wall. In the intake process, the airflow velocity in the middle of chamber is much higher than the one at both sides, even up to hundreds of times. In the compression process, the large velocity gradient in the trailing and high variation frequency in the leading are due to the shear and friction of the rotor face. (C) 2020 Elsevier Ltd. All rights reserved.