Transverse injection of rich, premixed, natural gas-air and natural gas-hydrogen-air reacting jets into high-speed vitiated crossflow at engine-relevant conditions

The transverse injection of rich, premixed natural gas and air (NG-air) and natural gas, hydrogen, and air (NG-H-2-air) reacting jets into a high-speed vitiated crossflow was investigated in this work at engine-relevant conditions. The high-speed vitiated crossflow at bulk velocities of approximately 114 and 256 m/s corresponds to crossflow Mach numbers of nominally Ma(infinity) = 0.15 and 0.35, respectively. For the Ma(infinity) = 0.15 crossflow, a minimum jet equivalence ratio near phi(J) = 1.4 was required to stabilize the NG-air flame near the elevated injector. Flame stabilization within the viewing window (up to approximately 90 mm downstream of injection) was not observed at Ma(infinity) = 0.35 for NG-air based on OH* chemiluminescence (CL) imaging. Hydrogen was added to the premixed jet and different levels of minimum hydrogen fuel fraction xH(2) were needed to stabilize the flame near the injector, depending on phi(J). For both NG-air and NG-H-2-air jets, flame stabilization near the injector resulted in a significant increase in Delta NOX emissions. The flame position and structure were observed to be different for very rich jets near phi(J) = 2.3 compared to moderately rich jets near phi(J) = 1.4, based on OH*-CL and OH planar laser-induced fluorescence. For Ma(infinity) = 0.15, reactions in the windward shear layer were also apparent at xH(2) near 60%. The measurements presented in this paper, to the best of our knowledge, are the first reported measurements in the literature for premixed NG-H-2-air reacting jets injected into a vitiated crossflow. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.