2014 Volume 56 Issue 175 Pages 80-87
To give an insight into wall material effect on the chemical quenching phenomena, a methane-air premixed flame formed in narrow quartz channels with metal wall surface is investigated. In the present study, stainless-steel321 (SUS321) and Inconel600 are chosen as the surface materials for high oxidation/heat resistivity. SUS321 and Inconel600 thin films ∼150 nm in thickness are deposited on polished quartz substrates by using vacuum arc plasma gun to establish equivalent thermal boundary condition for different wall surface reactions. OH-PLIF and numerical simulation with detailed reaction mechanisms are employed to examine interaction between the gas-phase and surface reactions. When the wall temperature is higher than 1073 K, the wall chemical effect starts to take over the thermal effect. It is shown through the PLIF measurements that OH* mole fraction near the SUS321 and Inconel600 surfaces becomes significantly lower than that near the quartz surface. By using a radical quenching model, the initial sticking coefficient S0 associated with radical adsorption is evaluated at the metal and the quartz surfaces. It is found that S0 are estimated to be 0.1 and 0.01 for the metal and the quartz surfaces. A series of numerical simulation is also made to examine the effect of S0 on the methane flame in micro channels. It is found that the wall chemical effect becomes of great importance for the gross flame characteristics such as the initiation temperature of the chain reaction and the heat release rate.
