Combined effect of intake angle and chamber structure on flow field and combustion process in a small-scaled rotary engine

Abstract

This work aims to reveal combined effect of intake angle and chamber structure on flow field, flame propagation, combustion characteristics and pollutants formation of a small-scaled rotary engine by using numerical simulation. For this reason, a three-dimensional dynamic simulation model was established by using a reasonable turbulent model and choosing a reduced reaction kinetic mechanism and was also validated by the experimental data. Simulation results showed that intake angle is more significant to the influence of flame propagation, in-cylinder pressure and heat release rate (HRR) in the front baffle combustion chamber (FBCC) and the rear baffle combustion chamber (RBCC) compared to that in the middle baffle combustion chamber (MBCC), but is an opposite trend for effect of flow field. The differences in the in-cylinder velocity field and turbulent kinetic energy magnitude were the intrinsic mechanism of combined influence of intake angle and chamber structure. Under larger intake angle, for the MBCC and the RBCC, higher pressure, HRR and power output were obtained, meanwhile the decreased HC and CO formations were obtained, while showed a contrary tend for the FBCC. And the amount of HC formation for these three combustion chambers at 15°intake angle is relatively small. To sum up, considering combustion characteristics, engine cooling and pollutants formation, it can be concluded that the combination of 15°intake angle and combustion chamber with a middle baffle was the optimum configuration for a small-scaled RE in engineering application. • The recess shape of rotor and intake angle are optimized. • Intake angle is more significant to the influence of combustion in FBCC and RBCC. • Recess shape plays a more significant role in effect of flow field and combustion. • Larger flow velocity and TKE near the spark plugs improve initial flame development. • The optimal scheme is the combination of 15° intake angle and MBCC or RBCC.