Effects of high-pressure methane jet on premixed ignited fl ame in constant-volume bomb

Direct injection (DI) technology imparts natural gas (NG) engines with high thermal efficiency and reduces emissions. Furthermore, NG directly jets into the pilot flame. The interaction between the NG jet flow and pilot flame has a significant influence on the initial ignition and flame stability. This study investigates the effects of a high-pressure methane jet on the pilot ignited flame, using a constant volume bomb (CVB) test rig. The interval between the methane injection and the ignition determines the premixed flame and jet combustion. The high-pressure methane jet flow collides with acts on the pilot premixed flame, which results in two phenomena: 1) Flame quenching: the premixed flame is blown off by the jet; and 2) Jet flame: the methane jet is ignited by the premixed flame. In the jet flame, laminar and turbulent flames co-exist. The development of the jet flame occurs in three stages: Stage I-the no-jet stage, wherein a laminar flame appears; Stage II-the interaction stage, wherein the jet interacts with the premixed flame, which results in either flame quenching or stable jet flame; and Stage III-the stable stage, wherein the flame becomes stable. (c) 2020 Elsevier Ltd. All rights reserved.