The interaction between the premixed flat flame and the water cooled cylindrical tube was studied. The stability diagram of the premixed flat flame was attained and the flame shapes without water tube were classified into the five cases.
The water tube located near the flame surface changes the flame shape from a flat flame to a bent flame. As the water tube moves upstream the local extinction occurs at the center of the bent flame. Such a local extinction is caused by both quenching and stretching. These effects are studied with changing the experimental parameters - mean velocity, diameter of water tube, equivalence ratio and temperature of tube surface.
As a result, as the equivalence ratio increases, the stretch intensity for local extinction increases. The decrease of the heat loss to the downstream also increases the stretch intensity for the local extinction.
