High-speed imaging of n-heptane ignition in a high-pressure shock tube

Homogeneous and inhomogeneous ignition modes of n-heptane were studied using high-speed imaging in a high-pressure shock tube (HPST). n-Heptane, fuel with strong negative temperature coefficient (NTC) behavior, was mixed 4%-21% oxygen argon or nitrogen ignited over wide range (700–1250 K) at elevated pressures (> 10 atm). Ultraviolet (UV) images OH* emission captured through sapphire shock-tube end wall camera UV intensifier. The current study demonstrates the capability to auto-ignition tube. Both homogeneous events observed latter generally confined intermediate temperatures reactive mixtures. We also that conventional sidewall diagnostic signals are, many cases, sufficient identify ignitions are not accurately modeled under assumption spatially uniform chemistry.