Thermal and Scalar Dissipation Rates of Stretched Cylindrical Diffusion Flame

Abstract

Structures of stretched cylindrical diffusion flame with large curvature were investigated experimentally. Temperature distributions of fuel-diluent mixture/air flames were measured. Fuel was diluted with diluent gases (N₂, Ar and He) in order to set the Lewis number Le～1. Fuel (Air) was supplied from inside (outside) of the cylindrical flame. Thermal dissipation rates were calculated from measured temperature distribution. In the case of Le=1, the scalar dissipation rate is proportional to the thermal dissipation rate. Therefore, the stoichiometric scalar dissipation rate was evaluated using the maximum value of the thermal dissipation rates obtained from each temperature distribution. Generally, it is known that the scalar dissipation rate of the counterflow flat diffusion flame increases as the flame stretch rate increases. However, in the case of the cylindrical diffusion flames, the scalar dissipation rate has a maximum value or decreases with the stretch rate.