Experimental study of suppressing effect of fine water droplets on propane/air premixed flames stabilized in the stagnation flowfield

Effect of fine water droplets on the laminar burning velocity of propane/air premixed flame was investigated by using a single jet-plate configuration. For the case without water droplets, the measured laminar burning velocities are in reasonably good agreement with previously reported data and the numerical simulation. The dependence of the burning velocity on the stretch rate for the case without water droplets is positive for all mixtures tested, resulting in the negative Markstein length, which coincides with previous experimental and theoretical studies. Water droplets lower significantly the laminar burning velocity and change its dependence on the stretch rate to negative. This leads to apparent positive Markstein lengths. The positive Markstein length was discussed on the basis of the droplets behavior in the stagnation flow field adopted in the present study. Even if the droplet mass loading was kept constant, the water droplets do not follow the diverting flow field when the stretch rate is high and the droplets accumulation occurs in the stagnation region where the burning velocities were measured. This fact results in the lower burning velocity as compared to that measured for uniformly dispersed water droplets.