The effect of Soret diffusion on stability of rich premixed hydrogen-air flames

The effect of thermal (Soret) diffusion on the structure, propagation speed and diffusional-thermal stability of rich hydrogen-air freely propagating planar premixed flames is investigated. Both the detailed mechanism and transport model is employed to study numerically the structure and stability of this flame. Warnatz detailed reaction mechanism is used. The obtained results, first of all, confirm classical asymptotic analysis by Garcia-Ybarra and Clavin [1]. Namely, the Soret diffusion moderately influences the flame speed and structure (even for hydrogen/air systems), but shifts significantly diffusional-thermal stability limits. Secondly, this study quantifies this phenomenon for reliable chemistry model and opens perspectives to use it as additional source of the detailed model validation. The structure of the diffusional-thermal stability limit as well as the structure of pulsating flame is thoroughly discussed.