Spanwise OH PLIF Visualization of Flame Structure and Location in a Dual-Mode Scramjet Combustor

Hydroxyl radical planar laser-induced fluorescence (OH PLIF) images were acquired over a dense array of spanwise measurement planes for an ethylene-fueled dual-mode scramjet cavity flameholder in the University of Virginia Supersonic Combustion Facility (UVASCF). Two fueling conditions were investigated: the first, using injectors located in the isolator; the second, using injectors located at the diverging wall just upstream of the cavity step. From these images, the three-dimensional volume of the flame intermittency for each condition was interpolated, revealing differences in spanwise structures between the two conditions. These results provide insight previously unavailable in similar facilities regarding the role of spanwise effects on the flame stabilization mechanism, which is typically imaged at the facility centerline. Implications for interpolating both path-integrated and centerline experimental data are discussed.