Effects of Incident Shockwave on Flame-holding Downstream of Ramp Injector in Supersonic Flow

Experiments and numerical simulations were conducted to explore the interaction between an incident shockwave and a flame-holding region downstream of a ramp injector. It was found that when an incident shockwave was introduced downstream of the ramp injector, a flame-holding region with red chemiluminescence accompanying high-temperature water vapor formed, while no apparent flame-holding region was observed without it. OH-PLIF measurements were also performed. The concentration of OH radical increased downstream of the incident shockwave, indicating that combustion was enhanced in the downstream region. Results of wall pressure measurements and numerical simulations indicate that the pressure increase and enhanced mixing contribute to flame-holding downstream of the incident shockwave. The mainstream was compressed downstream of the shockwave, resulting in an increased reaction rate between the hydrogen and mainstream air, as well as enhanced mixing due to baroclinic torque generated by the pressure gradient.