Investigation of Fuel and Load Flexibility of an Atmospheric Single Nozzle Jet-Stabilized FLOX® Combustor with Hydrogen/methane-Air Mixtures

Abstract In this work, a coaxial fuel nozzle was installed concentrically inside the outer air nozzle and was arranged in two different configurations. In the first, non-premixed case, the fuel and air nozzles were flush at the nozzle exit. In the second, partially premixed case, the fuel nozzle terminated 50 mm below the air nozzle exit. A third, fully premixed case was achieved by injecting fuel into an inline-mixer in the air 1 m upstream of the nozzle exit. Additionally, measurements were performed using fuel nozzles with two different sizes (inner diameters = 2 and 1.5 mm). For all these cases, percentage of hydrogen in the fuel was varied from 0 to 100 % (constant equivalence ratio, f = 0.74, thermal power Pth = 10.5 kW, jet exit velocity was kept at about vexit = 100 m/s at an air preheating Tpre = 300 K) and the resulting flames were characterized using 2D OH* chemiluminescence measurements. In addition, load-flexibility was investigated on the 100 % H2 case by varying the equivalence ratio (f = 0.74 to 0.21). Some selected conditions were further investigated using particle imaging velocimetry (PIV) to obtain velocity fields. The experimental results demonstrated a strong influence of nozzle configurations (mixedness), equivalence ratio and H2-content on flame shapes. Furhtermore, the results from this work are being used in a joint effort to validate numerical models for jet-stabilized hydrogen combustion.