Orthogonalization analysis of the effect of pre-combustion chamber hydrogen injection strategy on the combustion and emissions of a gasoline engine with active precombustion chamber under lean-burn condition

In the face of escalating environmental challenges, curbing gasoline consumption and enhancing engine thermal efficiency have emerged as top priorities. This paper focuses on a gasoline/hydrogen dual-fuel engine equipped with an active pre-combustion chamber. By utilizing hydrogen as the fuel for the active pre-combustion chamber, stable combustion under ultra lean-burn conditions has been successfully achieved. The impact of pre-combustion chamber hydrogen injection strategy on the engine lean-burn characteristics is investigated. To streamline the experimental process and identify the injection strategy that exerts the most significant influence on each engine combustion parameter, the orthogonalization method is adopted. Results show that engine combustion is significantly affected by the intensity of jet flame. Hydrogen injection timing determines the hydrogen concentration in the pre-combustion chamber during ignition, thus having the greatest impact on engine combustion. Due to the limited volume of the pre-combustion chamber in jet-ignition engines, the influence of hydrogen injection pressure is not obvious. Meanwhile, ignition timing determines the matching relationship between the combustion process and the combustion phase. “HIP of 3 MPa, HIT of 160°CA BTDC and IT of 15°CA BTDC” is the best injection control strategy.