Investigation of Short Contact Time Reactors for Regeneratively Cooled Hypersonic Vehicles

摘要

For hydrocarbon-based fuels to be viable as scramjet fuels they must be able to absorb heat from engine structures in the form of sensible, latent, and chemical enthalpies, while attempting to minimize coke formation. In this study, a short contact time catalytic reactor was used to achieve these ends. Experiments were performed using a series of different catalysts (Pt - A1_2O_3, Rh - A1_2O_3, and zeolite) on a set of logistical fuels (JP-7, JP-8, JP-10, and S-8, a synthetic hydrocarbon fuel currently being investigated by the U.S. Air Force). Experiments were performed at low (1-3 atmospheres) and elevated (40-50 atmospheres) pressures, at temperatures of 650 and 750℃. The production of gas- and liquid-phase species was measured as a function of pressure, temperature, residence time, and catalyst formulation. Results show the production of small (H_2, C_1-C_3) species in the gas phase, with a shift from hydrogen and ethylene formation at low pressures toward methane and ethane formation at elevated pressures. In addition, significant coke formation at elevated pressures for all of the fuels was witnessed. Detailed kinetic modeling identified shortcomings in models used for describing the pyrolysis of these fuels.