Droplet Combustion Of Surrogate And Real Fuel Systems In A Low Convection Condition: Ground-Based And Space-Based Experiments
The droplet burning characteristics of aviation (Jet-A) and ground transportation (gasoline) fuels, a standard reference gasoline (indolene), three and four component surrogate fuels, several biodiesel surrogates (methyl butanoate (MB) and decanoate (MD)), and three single component fuels (heptane, octane and decane) were examined from the perspective of the spherically symmetric droplet flame promoted by a low gravity environment in the standard atmosphere. The parameters included the initial droplet diameter (Do) and the fuel composition. Access to the experimental times required to observe the complete droplet burning history was obtained by carrying out the experiments in a drop tower that provided about 1 s of experimental time (Do < ~ 1 mm), and the orbiting International Space Station (ISS) using an experimental design on the ISS that could produce both freely-floating and fiber-supported droplets with essentially any Do and unlimited experimental times. For some of the results reported (those for n-heptane, n-octane, ndecane) Do was varied over the widest range ever reported (0.5 mm to 5 mm) across which radiative and sooting processes were considered to either influence burning (for Do > ~ 1.5 mm) or have a minimal affect (for Do < ~ 1 mm). For the other fuel systems investigated, Do was fixed at between 0.5 mm and 0.6 mm. Also discussed is a new imaging analysis method to automate data extraction from digital video records of the droplet burning history. The results showed the following: indolene droplets replicated reasonably well gasoline droplet burning; the three and four component blends examined performed closely to Jet-A; n-heptane and iso-octane mixture droplets did not replicate the burning characteristics of gasoline unless toluene was added to the mixture; the droplet burning rate decreases through the range of Do examined that spanned the ground-based and ISS data; and the ground based facility for studying fiber-supported droplet burning replicates quite well the burning characteristics of free-floating droplets of the same size and method of ignition. The value of the spherical droplet flame as a canonical liquid fuel burning configuration is shown for the complex fuel systems investigated.
droplet combustion; surrogate and biofuels; spherical symmetry
Avedisian, C Thomas
Zhang, Ke; Steen, Paul Herman
Ph.D. of Mechanical Engineering
Doctor of Philosophy
dissertation or thesis