Onset of thermal-diffusion instabilities in rich hydrogen/air premixed counter-flow twin flames

The effect of flame instabilities onset in the counter-diffusion twin flame configuration is investigated numerically. The onset of instabilities in rich hydrogen/air combustion system is reported and properties of pulsating solutions are studied. Effects of mixture composition and strain rate as well as pressure are considered. Same as in the freely propagating rich hydrogen/air flames the onset of pulsations is promoted by pressure increase. The increased strain rate as expected stabilizes the flame for high values of the strain but found to promote the onset of instabilities for moderate values. Because the onset of oscillating flame behavior is extremely sensitive to molecular diffusion and chemical kinetics the outcome of the study can be directly checked in the experiments. The results of the parametric study near the boundary and the properties of both pulsating and steady solutions can be used for additional combustion models validation.