300 kHz OH PLIF of Detonation Structure

The reaction field within detonations of methane-oxygen-nitrogen and hydrogen-oxygen-nitrogen are imaged with OH planar laser induced fluorescence (PLIF) at a rate of 300 kHz. Simultaneously, 5 MHz schlieren and broadband chemiluminescence measurements are acquired. The OH PLIF and chemiluminescence images are compared and small-scale structures are resolvable with the PLIF that are otherwise integrated over in the chemiluminescence. In the methane fueled mixture, an asymmetric transverse wave collision is analyzed and by overlaying the schlieren and PLIF images, localized reaction is observed within vortices ejected from the symmetry line of the collision. In a hydrogen fueled mixture, a Kelvin-Helmholtz instability is resolved along the shear layer between the high-speed shock and transverse wave. The OH PLIF signal tightly conforms to the vortices on the high-speed shock side of the shear layer. The formation of an unreacted gas pocket is captured and as the pocket convects downstream increased OH PLIF emission around the periphery suggests that it burns deflagratively.