Preliminary exploration of flow and combustion process in a hydrogen-diesel dual-fuel direct injection rotary engine

The hydrogen engine application is crucial for promoting carbon neutrality, while the hydrogen-diesel rotary engine development can reduce greenhouse gas emissions and promote hydrogen energy diversified utilization. Thus, hydrogen-diesel combined combustion technology is first proposed for rotary engines. Based on the means of parametric modeling, self-programming control and chemical reaction kinetics calculating, the in-cylinder flow and combustion process under different dual-fuel direct injection strategies and hydrogen blending modes are investigated. Results find that adopting the gaseous-liquid dual-fuel direct injection means can simultaneously realize the diesel and hydrogen stratified distribution, and interestingly the combustible mixture in-chamber forms an obvious "gas-in-oil" phenomenon. Specifically, diesel distribution in the front and middle chamber region presents rich in the leading part and thin in the trailing part, while hydrogen distribution in the chamber's middle and back region shows an opposite concentration distribution rule. The hydrogen lower direct injection with gas nozzle position lower the cylinder centerline 50 mm (Case-HLDI) is the optimized application scheme which has the highest peak pressure and that increases by 12.8 % and 11.3 % over the no hydrogen blending mode (Case-NHI) and the hydrogen intake port blending mode (Case-HPI). Moreover, its combustion rate also accelerates by 43.9 % and 17.9 %, respectively.