Analytical Investigation of the Effects of Vitiated Air Contamination on Combustion and Hypersonic Airbreathing Engine Ground Tests

摘要

A broad analytical study has been performed to define and evaluate the effects of vitiated air species contamination on combustion research development tests. The processes investigated include: equilibrium, chemical relaxation, vibrational relaxation, condensation, boundary layer and shock boundary layer interaction, combustion, mixing, and overall test engine performance. This study is concerned with the effects of hydrogen and propane vitiation in heating the working medium to temperatures of approximately 7000 degrees R. It is apparent that for the flight conditions investigated here, boundary layer phenomena and mixing are essentially insensitive to vitiation and that chemical equilibrium is adequate for facility nozzle flow determination. Furthermore, vitiation tends to enhance vibrational equilibrium. It is found, however, that the chemical kinetics of combustion and test engine nozzle recombination losses must be considered for both vitiated and pure air configurations. Condensation and combustion kinetics appear as the two most significant processes altered by the effects of vitiation. In general, it has been found that vitiation with propane in comparison with hydrogen results in substantially smaller mismatch in molecular weight while also extending the condensation limit. (Author)