Combustion performance improvement of a diesel fueled Wankel stratified- charge combustion engine by optimizing assisted ignition strategy

摘要

This work aimed to further improve the combustion performance in a diesel Wankel engine by optimizing the assisted ignition strategy. Based on the established and verified dynamic simulation model, the effects of some key assisted ignition parameters, such as the number of assisted spark plug, assisted ignition position (AIP) and assisted ignition timing (AIT) on combustion performance were analyzed systematically. Simulation results indicated that the reaction process occurred in the mid-anterior region of the rotary chamber due to the stratified-charge mixture and forward-propagate flame. The combustion performance of the double assisted spark plug schemes was better than that of the single assisted spark plug scheme. The double assisted spark plugs symmetrically distributed relative to the major axis (X-axis) of the rotary chamber, the combustion process was more reasonable. When changing AIP, peak combustion pressure (P-max) and combustion zone varied greatly, while they changed little when advancing MT. For the optimized assisted ignition strategies, the optimal AIP scheme was Case5 (0, -88.5, +/- 15 mm) and the optimum AIT scheme was Case7 (35 degrees CA BTDC). Comparing with the original scheme (Casel), their P-max increased by 16.68% and 17.83%, respectively. Meanwhile, the CA50 and CA10-90 were shortened obviously.