CHARACTERISTICS OF PARTIALLY PREMIXED ELLIPTIC BURNER FLAMES IN COFLOW- VELOCITY AIR STREAMS

摘要

This paper presents the results of an extension of the previous study where the effects of jet equivalence ratio and burner geometry on the characteristics of partially premixed propane/hydrogen/air flames at a coflow air velocity of 3 m/s were presented. The results here pertain to the experiments where the coflow velocity was doubled to understand the effects of coflow. Two different burner geometries (Circular, and 3:1 aspect ratio-AR elliptical burners) were used in the experiments with circular burner flames as baseline condition. During the study, the exit velocity was held constant at 20 m/s for all conditions. Stability tests indicated that circular burner flames were more stable than the 3:1AR elliptical burner flames at quiescent conditions. At 6 m/s coflow air velocity, stability of both the circular and the 3:1AR elliptic flames was enhanced. Circular burner flames were longer than 3:1AR elliptical burner flames. Introduction of 6 m/s coflow air velocity reduced the flame height. Global NO and CO emission indices decreased considerably after the introduction of coflow air in both burners. Peak temperature of circular burner flames was higher than that of 3:1AR elliptic burner at all conditions. Inflame concentration measurements were also taken in near-burner (25% flame height), midflame (50% flame height) and far-burner (75% flame height) regions.