와동과 상호작용하는 대향류 비예혼합화염의 비정상 응답특성

초록

A two-dimensional direct numerical simulation is performed to investigate the flame structure of CH4/N2-Air counterflow nonpremixed flame interacting with a single vortex. The detailed transport properties and a modified 16-step augmented reduced mechanism based on Miller and Bowman's detailed reaction mechanism are adopted in this calculation. To quantify the strain on flame induced by a vortex, a scalar dissipation rate (SDR) is introduced. Results show that the fuel and air-side vortex cause an unsteady extinction. In this case, the flame interacting with a vortex is extinguished at much larger SDR than steady flame. It is also found that air-side vortex extinguishes a flame more rapidly than fuel-side vortex. The unsteady effect induced by flame-vortex interaction does not lead to a transient OH overshoot of the maximum steady concentration observed in experiment, while HO2 radical increases more than the maximum steady concentration with increasing SDR. In addition, it is seen that NO and NO2 are not sensitive to the unsteady variation of SDR.