ISS Droplet Combustion Experiments - Uncertainties in Droplet Sizes and Burning Rates

Abstract

Methodologies are developed for evaluating uncertainties in droplet size measurements and burning rates for droplet combustion experiments that have been performed on the International Space Station. Different uncertainty sources are considered and propagated into the combined standard uncertainties via the Taylor series method. The local polynomial method is used to provide estimates of instantaneous burning rates. Results from analyses of non-sooting (methanol) or lightly sooting (heptane) droplets as well as moderately sooting (decane/propylbenzene) droplets are presented. Ninety-five percent expanded uncertainties in droplet diameters and burning rates are typically about 0.1 mm and 0.005 mm 2/s, respectively, for methanol and heptane droplets and 0.1 mm and 0.02 mm 2/s for decane/propylbenzene droplets, though uncertainties can be larger during ignition and extinction events.