EFFECT OF FUEL CHEMICAL COMPOSITION ON SUPERCRITICAL REACTIVITY AND DEPOSITION PROPENSITY

摘要

The successful development and implementation of hydrocarbon-fueled high speed aerospace platforms require advanced concepts to enable sufficient heat sink for vehicle and engine cooling. This requirement is necessary due to the large quantity of waste heat generated at high speeds which cannot be effectively managed via indirect cooling strategies, such as with "cooled cooling air." A primary route to achieve required levels of heat sink is to use the on-board fuel as the primary coolant, where the sensible heating enthalpy is supplemented by deliberate bulk endothermic reactions of the fuel via thermal and/or catalytic cracking chemistry. However, a major limitation to viable implementation is the undesirable formation of carbonaceous deposits, which can reduce fuel flow, increase resistance to heat transfer and foul injector nozzles. Therefore, improved understanding of the effect of fuel chemical class composition and physical properties on fuel reactivity and deposition propensity is required to develop viable hydrocarbon fuels for endothermic applications. This understanding is critical since it provides insight into chemical and physical properties which control reactivity and deposition propensity and the basis for development and evaluation of advanced methodologies (e.g., materials, coatings, catalysts) to enable hypersonic applications. The Air Force Research Laboratory and University of Dayton Research Institute have developed experimental and analytical capabilities for evaluating fuel reactivity and deposition propensity under endothermic (supercritical fluid) reaction conditions. An overview of these capabilities and results from representative studies are presented.