Effect of a Transition in a Fuel Species Fraction on the Behavior of a Bunsen-Type Premixed Flame

Effect of transient variation in the fraction of components in the multi-component fuels on the characteristics of a Bunsen-type burner has been investigated experimentally. Methane/ethane/propane three-component fuel, methane/ethane two-component fuel and methane/propane two-component fuel were used. The flame motion under the linear transition from one fuel mixture to another was examined. The transition time was varied from 1 s to 10 s, keeping the flow velocity and the equivalence ratio constant at 0.8 m/s and 0.85 respectively. The variation in the flame height was measured, using high speed video camera at 125 fps. Experimental results showed the overshoot of the flame height in an upward or downward direction during the transition. The magnitude of the overshoot was larger for shorter transition time and for larger difference of volume fraction of fuel components. The difference in diffusion coefficient of each fuel is supposed to play an important role for the overshoot.