高温高压环境下正己烷喷射燃烧的现象学

The combustion process of sub-critical n-hexane injected into sub- and super-critical environments near the critical point was studied on a constant volume combustion vessel. The image information was collected by a high speed camera and optical test system. This test was to explore the difference of n-hexane injection and combustion process in the sub- and super-critical environments which have the same temperature but different pressures. The experimental results show that, with the increase of the ambient pressure, the ignition delay shows a tendency of decreasing first and then increasing, reaching a peak value near the critical point. After entering into the super-critical pressure range, the ignition delay exhibits a decreasing trend. The ignition starting point is gradually close to the nozzle along the nozzle axis with the increase of the ambient pressure, but there is a trend of increasing first and then decreasing near the critical point. The flame in the super-critical environment has larger flame cone angle than that in the sub-critical environment, which is caused by the difference of injection fragmentation and gasification under suband super-critical environments.