Combustion of Liquid Fuel Sprays in Stagnation-Point Flow

Abstract

The steady combustion of polydispersed sprays of ethanol and kerosene in the stagnation-point flow of lean methane/ air mixtures is experimentally investigated. Using laser Doppler velocimetry, the axial and radial velocity profiles of the dropletsare measured for water sprays in the presence or absence of lean methane/ air flame. These results are then compared with the velocity profiles obtained for small MgO particles under identical flow conditions. The results show the effects of gas expansion on droplet deceleration (acceleration) in the pre-flame (post-flame) regions. Also, it is found that addition of water spray results in the formation of a distributed region of yellow-orange emission downstream of the lean methane flame. In combustion of ethanol spray, certain critical fuel-concentration/ velocity limits are identified above which the flame becomes acoustically unstable. The implications of the study to the modeling of turbulent spray combustion are discussed.