| Endothermic hydrocarbon fuel (EHF), as a kind of flammable coolant, was proposed in order to solve the thermal management problem of the hypersonic vehicles. It can serve as both propellant and coolant for hypersonic aircraft. EHF can provide the additional heat sink by undergoing chemical decomposition prior to injection into combustor. Because the composition of fuel was complex, blended model fuels were usually studied as alternative fuel samples in laboratory. The main contents of endothermic fuel were cyclanes and chain alkanes. So, the explorative study in this thesis was emphasized on pyrolysis of blended fuels of cyclanes and chain alkanes.JP-10 was chosen as a sample of cyclanes. n-Octane and i-octane were representative of chain alkanes. Thermal cracking of these model compounds and the blended fuels, including JP-10/n-octane and JP-10/i-octane in different proportion, were studied at different temperature. The results showed that the decomposition conversions of JP-10 and n-octane in mixtures were lower than those of pure compounds. The experimental values of the overall conversion were lower than the calculated conversion under the conditions of this experiment. However, the presence of i-octane initiated the decomposition of JP-10 while JP-10 inhibited the cracking of i-octane in blended fuel. The experimental conversions were higher than the calculated values in all the range of experiments. Considering the various factors, including density, the selectivity of alkene in the gaseous products, the yield of cokes and so on, the optimum content of n-octane was about 30%-50%(mass fraction) in JP-10/n-octane and i-octane was about 10%-30% in JP-10/i-octane.Pyrolysis of decalin and the blended fuels of decalin with n-octane or i-octane in different proportion were studied. The results showed that n-octane accelerated the cracking of decalin, while that of n-octane was inhibited in decalin/n-octane. And the overall conversions were lower than the calculated values. The addition of i-octane observably initiated the cracking of decalin, but the conversion of i-octane was inhibited. The overall conversions were increased compared with the calculated values. The experimental results indicated that the optimum content of n-octane was about 30% in decalin/n-octane and i-octane was 10%～30% in decalin/i-octane.The pyrolysis of decalin catalyzed by oil-solubility nickel nanoparticles was investigated in the pseudo-homogeneous condition. Results showed that the decomposition conversion can be increased by 240% compared with the thermal cracking at 610℃, and 110% even at 670℃. The content of H2 was increased in the gas products of catalytic reaction, which can improve ignition performance. The yield of cokes was increased with increasing conversion of catalytic cracking and their morphologies were filamentous.The feasibility of adding alkanol into hydrocarbon fuel as additive was also discussed. The densities and viscosities of the blended fuels of JP-10/n-butanol and JP-10/n-pentanol were determined over the entire composition range. The thermodynamic properties derived from these data can provide important information for studying the blended fuels. It was found according to the experimental results that the addition of n-alkanol has effect on the pyrolysis of JP-10, but the results showed no apparent trend.
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