Experimental Study on Random Autoignition of N-Decane Spray in Crossflow at Evaluated Pressure

Abstract

Abstract Based on a flow reactor with optical access, the statistical characteristics of the autoignition of n-decane spray injected by transient transverse column jet into non-vitiated crossflow were studied at various conditions relevant to gas turbine combustor: the reactor pressure of 1.7MPa, the air temperature of 785–1000 K, the jet-to-crossflow momentum flux ratio of 55 and 72, the air Weber number of 290. The ignition delay time was defined as the time interval between the fuel injection into the flow reactor and the radical emission from ignition kernels. The results demonstrate that the ignition delay time of n-decane spray exhibits a random behavior in a given operating condition. In addition, the experimental probability densities of the ignition delay time were determined by statistical method. The results show that with the increase of temperature and momentum flux ratio, the statistical distributions of the ignition delay of the spray become more concentrated, and the sample data of ignition delays have smaller overall-central value in statistics. Furthermore, based on the images of fuel spray of n-decane taken by a high-speed camera, the results indicate that the random behavior of spray autoignition is associated with the random distribution of fuel concentration in spatial and temporal, which is mainly caused by the unsteady jet primary breakup and atomization process.