Influence of fuel type on turbulent nonpremixed jet flames under MILD combustion conditions

Abstract

This paper reports on the systematic variation of fuel type for turbulent nonpremixed flames issuing into a heated and diluted coflow. The coflow oxidant stream achieved using the jet in hot coflow (JHC) burner emulates MILD (Moderate or Intense Low oxygen Dilution) combustion conditions. Combined laser diagnostic imaging simultaneously reveals the in-situ spatial distribution of the hydroxyl radical (OH), formaldehyde (H2CO) and temperature. In this work, three different fuels are considered, viz., natural gas, ethylene, and LPG (each diluted with hydrogen). The influence of the fuel chemistry on the flame behaviour and reaction zone structure is examined. It is observed that under MILD combustion conditions there does not seem to be a significant effect of the fuel type on the structure of the reaction zone. The fluidic structure of the turbulent jet appears to control the flame more so than the chemistry in the MILD combustion conditions of the JHC burner.