Effects of the concentration gradient and mean velocity on the triple flame have been studied experimentally using a multi-slot burner, which can control the concentration gradient and the mean velocity independently. Main difficulties of the experiments were caused by experimental disturbances and the dependency of the concentration gradient on the mean velocity. In this paper the triple flame could be stabilized successfully in lift off condition. Flame stabilization condition, liftoff heights, and some other characteristics were examined for methane and propane flame. Mass spectroscopy and Rayleigh scattering signal were used to measure the concentration gradients, and LDV was used for velocity. We can find that propane flame is more stable than the methane flame and minimum values of the liftoff heights exist at a certain concentration gradient for constant mean velocity. The scales of flame to the burner nozzle and intensity variation of the diffusion flame were suspected as the cause.
