Experimental studies on the OH∗ chemiluminescence and structure characteristics in NH3/H2 and NH3/cracked gas swirl flames

Abstract

Ammonia (NH3) has been gaining popularity as a carbon-free alternative fuel in recent years. OH∗ chemiluminescence is a promising method to study the structure of ammonia flames, but research on this aspect is still lacking. In this study, the OH∗ chemiluminescence distributions and structure characteristics in NH3/H2 and NH3/cracked gas swirl flames are experimentally investigated. The OH∗ distributions of NH3/H2 and NH3/cracked gas under different addition levels and equivalence ratios are compared. The results show that the increase of equivalence ratio and hydrogen doping level significantly increased the OH∗ chemiluminescence peak of NH3/air swirling flame. Especially in fuel-lean flames, the equivalence ratio effect is greater than the NH3 dilution effect, while the two effects are comparable in equivalence and fuel-rich conditions. The stretching effect of NH3/cracked gas is stronger, and the flame width is narrower than that of NH3/H2 flame, but the peak value of OH∗ radiation is higher.