Structure and stabilization of hydrogen jet flames in cross-flows

Abstract

The structure and stabilization of heated hydrogen jet flames in heated cross-flows was experimentally investigated in a configuration that is analogous to terrestrial gas turbine components. Three flames, with jet velocities ranging from 100 to 200 m/s, were investigated using particle image velocimetry and OH planar laser induced fluorescence in a total of 11 x–y and y–z planes. Additionally, laser Raman scattering was performed in the 200 m/s jet to characterize the thermo-chemical state. In all cases, the flame along the jet centerline plane consisted of two branches, one stabilized in the jet lee and one lifted above the jet trajectory. The positional stability of the lee-stabilized branch was greater in the higher jet velocity cases due to the larger and stronger recirculation zones created downstream of the injection point. The lifted flame branch was much more dynamic, with measured flame base axial positions ranging from the jet near field to the flame tip. This flame branch instantaneously resided downstream of regions with high extensive principal strain-rate, and the strain-rate significantly affected the thermo-chemical state. The Raman measurements indicated that the base of the lifted flame branch existed in locations where both tribrachial and/or stratified premixed flame behaviors are expected, depending on the instantaneous flame location. Accurately modeling these complex flame structures and flow-flame interactions therefore is necessary to properly simulate jet flames in cross-flows.