Characterization of a Single-Nozzle FLOX^® Model Combustor Using kHz Laser Diagnostics

A single-nozzle FLOX^® model combustor was used to produce a confined, premixed CH₄-air flame with an equivalence ratio of ϕ = 0.74 and a jet exit velocity of v_jet = 150m/s with a preheat temperature of T₀=300°C. For the first time for this combustor, surface thermometry was performed on the chamber walls. In addition, particle imaging velocimetry (PIV) and planar laser-induced fluorescence of hydroxyl radical (OH PLIF) were acquired simultaneously in this flame at 5 kHz repetition rate. The interface between burnt and unburnt gas mixture were identified from instantaneous OH PLIF images and were compared with corresponding PIV results for flame-turbulence interaction analysis. Combustion instabilities were analyzed via proper orthogonal decomposition and phase-averaged flow field and OH distribution. A pronounced flapping motion of the jet was identified and its impact on the recirculation of hot burnt gas was characterized.