Enhancement mechanism of jet ignition mode on the combustion performance of rotary engine fueled with pure methanol

Methanol is a promising renewable fuel and hydrogen carrier for rotary engines, offering a sustainable solution to reduce carbon emissions. Additionally, jet ignition technology, with its advantages of high ignition energy and multi-point ignition capability, can be utilized to enhance the combustion efficiency of pure methanol rotary engines. As the core component of the jet ignition system, the structure of the pre-chamber determines the jet ignition intensity, thereby influencing in-cylinder flame propagation and combustion efficiency. This study focuses on the effects of shape and volume of pre-chamber on ignition and combustion in pure methanol rotary engines. The results demonstrate that the influence of pre-chamber shape on in-cylinder flame propagation speed is primarily manifested in the methanol mass and turbulent kinetic energy intensity within the pre-chamber at ignition timing. Meanwhile, the impact of pre-chamber volume on in-cylinder flame propagation speed stems from a contradictory relationship induced by increasing volume: while it enhances jet flame intensity, it simultaneously delays the entry timing of the jet flame into the cylinder, establishing a nonlinear correlation between pre-chamber volume and in-cylinder combustion efficiency.