Sajjad Mohammadnejad, Amirhossein Azimi, Ritesh Kumar Maurya, Ömer L. Gülder
The flow field, spray characteristics, flame chemiluminescence, soot volume fraction, and exhaust gas emissions were investigated in a hydrogen–Jet A-1 dual-fuel model gas turbine combustor. Measurements were performed using stereoscopic particle image velocimetry, Mie scattering, Fraunhofer diffraction-based spray droplet sizing, OH ∗ chemiluminescence imaging, laser-induced incandescence, and exhaust gas analysis. The nominal thermal power and fuel–air equivalence ratio were fixed at 8.83 kW and 0.64, respectively, with hydrogen contributing 0% to 45% of the power. Hydrogen was premixed with the airflow prior to combustion, and the liquid Jet A-1 was sprayed using a pressure-swirl atomizer. Hydrogen addition was found to influence the flow field by altering the size of the recirculation zones and shifting the location of the stagnation point. A strong connection was identified between the shape and behavior of the spray cloud and OH ∗ chemiluminescence. Without hydrogen enrichment, both the spray cloud and OH ∗ chemiluminescence formed a solid conical structure and featured a bimodal behavior. While hydrogen addition up to 25% transformed their structures into hollow cones, further enrichment led to the formation of a secondary combustion zone downstream. This was attributed to the preignition of the hydrogen–air mixture near the spray nozzle and the increased spray droplet size. The soot volume fraction decreased with hydrogen addition up to 25%. However, a sharp increase was observed at higher hydrogen enrichment levels, primarily due to the hydrogen–air mixture preignition. Considering the combustion emissions, 25% hydrogen enrichment appeared to be the optimal operating condition of the utilized combustor, resulting in nearly zero soot and CO emissions, as well as reductions of approximately 25% and 32% in CO 2 and NO x emissions, respectively. Novelty and significance statement : The soot volume fraction distribution and reactive flow field of a hydrogen–Jet A-1 dual-fuel model gas turbine combustor are experimentally measured for the first time. Only a few studies have examined hydrogen–Jet A-1 dual-fuel combustion in such combustors, especially where gaseous hydrogen is premixed with the airflow and liquid Jet A-1 is sprayed into the combustion chamber. The effect of hydrogen addition on the relation between spray and flame characteristics is also investigated to address the corresponding gap in the literature. Additionally, the spatial relations among flow and flame features, including the velocity field, spray cloud, flame chemiluminescence, and soot distributions, are studied.