抄録
In this study, we measured soot and NO_x in a cyclone-jet combustor. A laser induced incandescence (LIT) technique was applied to obtain instantaneous soot concentration. As for NO_x emission, premixed and non-premixed combustion were examined with changing equivalence ratio. To discuss the flame structure and flame characteristics in detail, numerical simulation on a jet diffusion flame was conducted. The location of ignition point was moved to discuss the effect of mixing between fuel (propane) and air in combustor. The flame index was obtained to estimate the premixed and nonpremixed combustion region. The mixedness was also examined to distinguish the region of lean or rich premixed mixture. Results show that, when the air volume rate is increased, EINO_x in nonpremixed combustion is reduced to the level of premixed combustion. The soot is not detected when the equivalence ratio is less than 2. Based on numerical simulation, the degree of propane and air mixing is increased when the location of the ignition point is moved downstream. Resultantly, the local equivalence ratio is decreased with lower flame temperature. Hence, the low level of NO_x emission in a cyclone-jet combustor is explained by this partial premixing effect of fuel and air.
