COMPARING SPRAY AND FLAME BEHAVIOR IN A SWIRL LIQUID FUELED LEAN BURNER WITH SINGLE AND MULTIPOINT INJECTIONS

Recent advances in gas turbine combustor design aimed at achieving low NOx emissions have focused on locally leaner combustion by rapid mixing of fuel and air. Multipoint injection leads to a fast and efficient mixing with the control of the spatial fuel distribution. In the present work, an experimental study on combustion phenomena in a liquid fuel burner, which operates in non-premixed (single point injection) and partially-premixed regimes (multipoint injections), was carried out in order to investigate the effect of the injection mode. In both the cases the lean combustion behavior was investigated in proximity of the blow-out limit. An intensified high rate CCD was used for flame imaging in the ultraviolet spectral range. It was equipped with different optical filters to selectively record single species chemiluminescence emissions (e.g. OH*, CH*). Analogous filters were also used in association with photomultiplier (PMT) tubes. Finally the NOx emissions were monitored. Furthermore, preliminary computational fluid dynamic (CFD) simulations were also performed under the typical combustor operation conditions to provide insight into the mixing of the air and the fuel under the different injection modes and the related flame pattern.