Effect of Aviation Fuel Type on Pyrolytic Reactivity and Deposition Propensity under Supercritical Conditions

Development of reusable liquid-hydrocarbon-fueled hypersonic vehicles requires improved understanding of the effect of chemical composition on the controlling reaction chemistry and deposition propensity as the fuel is used to cool the system. In this effort, supercritical pyrolytic stressing studies were performed using two petroleum-derived fuels and a Synthetic Paraffinic Kerosene (SPK) comprised predominantly of normal and branched paraffins. All fuels decomposed via free radical pathways with high yields of unsaturates and lower molecular weight products consistent with pyrolysis at high pressures and moderate temperatures. However, the SPK was significantly more reactive than the petroleum-derived fuels due to a lack of efficient hydrogen donors that act to terminate chain reactions (higher net propagation rate). High-pressure liquid chromatography was used to identify and quantify polycyclic aromatic hydrocarbons (PAH) in the stressed fuels, conclusively determining that these are produced during t...