热伴流中甲烷射流的自燃特性研究

High-speed CH^*chemiluminescence measurements were performed to investigate the auto-ignition behavior in methane jet-in-hot-coflow flames. The temporal evolution of growth rate of auto-ignition kernel，aspect ratio，and movement velocity of the kernel centroid were extracted under different jet velocities and equivalence ratios. Results showed that the auto-ignition location becomes lower with the increase of jet velocity. Further increase of jet velocity no longer lowers the occurrence location of the kernel，but it suppresses its growth. With the same jet velocity and equivalence ratio，the growth rate and aspect ratio of auto-ignition kernels are very sensitive to coflow temperature. Under low coflow temperature，the auto-ignition kernels grow more quickly and have a similar aspect ratio to a sphere. Under high coflow temperature，the aspect ratio increases with jet velocity，meaning that the auto-ignition kernels grow in an ellipse expanding manner rather than in a spherical manner.