A Study on the Combustion Characteristics of a methane jet flame in a Pressurized Hot Vitiated Co-flow 2019-01-0082
This work presents the study of the methane jet flame in a pressurized vitiated co-flow burner (PVCB) ,which can provide a controllable high pressurized temperature zone and oxygen atmosphere and simulate the temperature of the first stage low temperature exothermic combustion of the homogeneous charge compression ignition (HCCI) engine. The lift-off length and the stabilization of the methane jet flame under different environment pressures, co-flow temperatures, co-flow rates and jet velocities have been studied, and a Chemkin numerical simulations with Gri-mech 3.0 were analyzed as well. The results could provide theoretical supports for the research of the natural gas engine combustion stabilization control to increase the indicated thermal efficiency of internal combustion engine. The experimental results show that the lift-off length decreases obviously (104.22mm-76.14mm) with the increase of the environment pressure (1-1.5bar, 1073K) and temperature (119.34mm-43.74mm from 1058K to 1113K, 1bar), and increases with the increment of the co-flow rate and jet velocity. The stabilization of the lift-off length tends to be better and the methane jet flame tends to be brighter with the lift-off height decreases under all operation conditions. The results indicated that the lift-off length and the stabilization of methane jet flame are sensitive to the co-flow temperature and the environment pressure. By the numerical simulation, the auto ignition delay of the methane decreases with the increase of the environment pressure and co-flow temperature, the minimum auto-ignition temperature of the methane/air pre-mixture decreases with the environment pressure increases. The numerical results showed temperature and environment pressure are the key factors resulting in the decrease of the lift-off height. It indicated that the increment of the environment pressure could promote the combustion reaction.