Imaging and radiation of laminar jet diffusion flames with low coflow air velocity in microgravity

摘要

We present imaging results and radiation measurements from laminar jet diffusion flames burning in coflowing air conditions. Color and pseudocolor flames are obtained and used to analyze flame brightness and shape, which show that flames under normal gravity are brighter than in microgravity. The longer residence times for microgravity flames result in increased radiative loss, which leads to local extinction and low temperature at the flame tip. Flame radiation fractions for microgravity flames are larger than those in normal gravity for C_2H_4 and CH_4. The velocity of coflowing air has a much more pronounced effect on radiation from microgravity flames compared to those in normal gravity. The radiation fractions from ethylene-fueled flames in microgravity are large, leading to local extinction at the flame tip. We also analyzed the flame radiation fraction.