Pre-chamber study for combustion improvement in TJI direct-injection Wankel engine fueled with methanol–gasoline blend

Wankel engine has a wider application in the power field because they have fewer components, high power density, and fuel diversity. For its high-efficiency and low-carbon combustion, using gasoline blended with a 20% energy ratio of methanol as fuel, the simulation study based on turbulent jet ignition (TJI) technology was carried out on a direct-injection (DI) rotary engine in terms of the mixture distribution and combustion performance. Impacts of the orifice diameter (d), top height (H), and throat diameter (D) of the passive pre-chamber on engine combustion performance were investigated. The results show that d directly determines the fuel mass and jet flame rate in the pre-chamber, and smaller d can result in insufficient jet energy. H primarily affects the flame propagation distance. At H = 7.0 mm, the main chamber has the most OH radicals, and the engine exhibits relatively excellent performance. Larger D enhances the lateral flame propagation in the pre-chamber throat, which is not favorable to the centralization of flame propagation. Wankel engine has the best power and combustion performance when d = 1.75 mm, D = 6.0 mm, and H = 7.0 mm. Compared to H and D, d shows a more noticeable influence on combustion performance and has a higher correlation coefficient.