Numerical Investigation of the Effect of Intake Closing Timing on Flow Field and Combustion Process in an Elliptical Rotary Engine

Abstract

The aim of this research is to investigate the effect of intake closing timing (ICT) on the flow field and combustion process in elliptical rotary engines. The model that can accurately describe the working process of the elliptical rotary engine was established, five kinds of ICTs were designed, and the influence of ICT on the flow field and combustion process was studied. The results show that the advance of the ICT can increase the intake mass flowrate and reduce the back flowrate, the volumetric efficiency is 86.1% at a 145-deg crank angle (°CA) before top dead center (BTDC), which is 7.6% higher than 125 °CA BTDC. The advance of the ICT improves the consumption speed, makes the combustion reaction more intense, and shortens the combustion time. When the ICT is 145 °CA BTDC, the crank angle when the burned mass fraction is 90% (CA90) is 19.4 °CA earlier than 125 °CA BTDC, the peak mass of hydroxy in a cylinder is 41.6% higher, and the peak pressure in a cylinder is 25.9% higher. With the advance of the ICT, the pressure and heat release in the cylinder are significantly increased, the peak temperature in the cylinder is increased, the rate of carbon monoxide generation is accelerated, and the mass of nitrogen oxide emission is significantly increased. However, advancing the ICT cannot improve the indicated thermal efficiency of the elliptical rotary engine. This analysis provides a comprehensive understanding of the ICT of elliptical rotary engines.