Formaldehyde LIF-Diagnostics of the Autoignition of n-Decane Droplet Pairs in Microgravity

Abstract

The interaction between two neighboring n-decane droplets during the autoignition process in air was experimentally investigated under microgravity conditions in the drop tower Bremen. The initial droplet diameter was 0.8 mm in all experiments. Single droplets and droplet pairs with a center distance of 1, 2, 4 and 6 mm were investigated. The air temperature was varied between 650 and 850 K with an increment of 25 K. The examined pressure conditions were 0.3 and 0.5 MPa. This results in a total number of 90 drop experiments. The ignition process was observed applying the laser induced fluorescence (LIF) on formaldehyde with high temporal and spatial resolution. Both, the cool flame process and the hot flame ignition could be measured regarding induction times and the temporal and spatial evolution of the formaldehyde formation.