Investigation Of A Premixed Reacting Jet In An Unstable Transverse Flow Field

The combustion dynamics of a premixed air-natural gas jet injected into a high temperature, high pressure, acoustically oscillating crossflow were investigated experimentally and analytically. Both fuel-lean and fuel-rich premixed jets were studied. The equivalence ratio of the crossflow was adjusted so that in both cases the overall equivalence ratio was about 0.6. The combustion response of the jet was optically recorded by means of filtered combustion light and a high speed camera. Spatially dependent flame responses were seen at approximately the same frequencies as the 1st and 2nd acoustic modes which characterized the unsteady crossflow oscillations. Two distinct regions of response were found, an upstream region that coincided with an upstream-running velocity perturbation and a downstream region that coincided with a downstream-running velocity perturbation. As expected, the fuel-rich jet injected into the lean crossflow showed a stronger response. The phase angles between the intensity response and the velocity oscillations were analyzed. Stability maps were created from an analytical model that was developed based on the flow conditions and experimental results. Approximate operational regions were determined from literature and experimental results and were represented on the stability maps. © 2011 by Siemens Energy