Sooting tendencies of propane jet diffusion flame under crossflow

摘要

Understanding the sooting tendencies of turbulent flames under windy conditions is important to mitigate air pollution from flare stacks as well as improve flame detection of unwanted fires. Previous studies have focused on the smoke point of flames in still air with few investigating the effects of crossflow on the smoke point. In this study, experiments examining these tendencies of propane jet diffusion flames under wind-tunnel conditions were performed. The Reynolds number, Froude number (Fr), and jet-to-crossflow momentum flux ratio (R-M) ranged between 177-3305, 0.02-756, and 0.0005-124, respectively. Flames were classified as buoyancy-controlled or momentum-controlled on the basis of Fr values. With increasing wind velocity, both the flame length and smoke particle number concentration first increased and then decreased. If values of these two parameters both fulfilled the critical criteria, the smoke-point condition was well-determined. At the smoke point, to suppress soot production and mitigate soot emissions, the wind velocity needs to be increased with higher growth rates for buoyancy-controlled flames than for momentum-controlled flames. Correspondingly, R-M and Fr have a power-law relationship 1/R-M= 62.66Fr(-0.829).