Lift-off region temperature field and planar flow field of a twin-nozzle reacting jet in hot crossflow

Abstract

Secondary fuel injection affects the combustion organization and flame dynamic in axial fuel staging gas turbines. Here, we experimentally investigate a front-fuel rear-air twin-nozzle configuration in which the fuel and air can be independently injected to stabilize a lifted flame front, control the jet trajectory and tune the combustion mode in a very flexible way. A high repetition two-line formaldehyde planar laser induced fluorescence thermometry technique is used to measure the lift-off preheat zone temperature field of the flame with different amount of secondary air injection. The combustion flow field and the flame front dynamics are investigated using particle image velocimetry and CH* chemiluminescence. When the air to fuel ratio increases from 0 to 3, the preheat zone temperature, which is affected by the local equivalence ratio and injection air cooling, increases from 1300 K to 1600 K and then slightly declines. The lift-off region temperature and flow field dynamics are related to the variation of lift-off height, heat release rate and stability of the reacting jet in hot crossflow.