Detailed numerical simulations for the multi-stage self-ignition process of n-decane single droplets with complex chemistry

The knowledge of droplet self-ignition processes as the basic element of spray ignition is necessary for many combustion applications. Detailed numerical analysis for the self-ignition process of n-decane single droplets showing the multistage self-ignition behavior of kerosene, are carried out for this study. A substantial chemical reaction model for n-decane with 603 reactions including 67 species is implemented in a former validated detailed one dimensional numerical simulation model for droplet ignition. This reaction mechanism pays special attention on the low temperature reaction path and the balance between high temperature and low temperature reactions. In the compared experiments the staged ignition process is detected by observing the temperature gradient with a Michelson interferometer, which is the numerical tracer for cool flame and hot flame appearance as well. The comparison between the results from the simulations and the experiments under microgravity conditions carried out to Drop Tower Bremen shows good agreement. Furthermore the numerical observation of important species like OH or formaldehyde is possible due to the implementation of detailed chemistry. This gives hints for other experimental methods to detect the multi-stage self-ignition behavior like formaldehyde-PLIF, which is meanwhile an approved tracer in the experiments, so that there is vice versa a further possibility to validate the present numerical model.