气缸润滑油自燃诱发低速二冲程氢气发动机早燃实验研究

Cylinder lubricating oil is considered the main responsible for the pre-ignition in low-speed two-stroke hydrogen engines. To understand the characteristics of the pre-ignition induced by cylinder oil, experimental research was carried out under in-cylinder conditions of low-speed two-stroke hydrogen engines based on an RCM. The optical experiment verified that the auto-ignition of single oil droplets could induce hydrogen pre-ignition under engine-like thermodynamic conditions. Compared with natural gas engines, the pre-ignition of hydrogen engines has the characteristics of earlier occurrence time, higher maximum combustion pressure, and faster flame propagation. And the pre-ignition is usually accompanied by an engine knock. The reduction of excess air coefficient (λ) promotes the occurrence of pre-ignition accompanied by varying degrees of engine knock. To avoid the accompanying knock in pre-ignition, the excess air coefficient of 2.5~3.0 is appropriate, under the condition of satisfying the thermal efficiency. And these findings are beneficial to understanding the characteristics and mechanisms of pre-ignition induced by the auto-ignition of cylinder oil droplets.