Abstract
In the general combustor, fuel and air are fed separately and combustion occurs primarily within a spacially limited zone. Turbulent mixing rates in such a system have important effects on the emission of pollutants such as unburned hydrocarbons and soot.
The main purpose of the present paper is to investigate on the control of the soot emission due to the different swirling intensities of combustion air flow. The blades of the swirl generator can change continuously from 0° to 70° (θb : swirl angle) in order to increase the tangential velocities. Characteristics of soot emission are measured in propane/air diffusion flames of two typically different combustor of parallel and enlarged types paying special attention to the roles of gas temperature on the behavior of soot formation and decomposition in the flames. Profiles of soot concentration together with gas temperature and entrainment rate of O2 are measured in all flames.
When the swirl angle (θb) is raised, both of the soot formation and decomposition rates increases. The larger angle of the θb results in the lower exhaustion of soot. However, in the enlarged combustor, finally exhausted soot concentration in the θb=70° becomes much higher than that in the smaller angle θb=60° for the decay of soot decomposition in the down-stream.
