Jet Exhaust Reactions: A Theoretical Study

The objective of the project was to find an appropriate means for temporarily reducing the temperature of engine exhaust gases while holding to a minimum the infrared spectral emission in the reaction products at the exhaust temperature. The most promising approach appears to involve the injection of materials that undergo endothermic decomposition. Only limited data on endothermic decomposition were found in the literature. However, heat of decomposition values can be calculated from heat of formation data which is much more readily available. Some promising substances were tested by injecting their powders into a hot gas stream and measuring the temperature reduction thereby induced. Preliminary calculations based on these measurements indicate, typically, that engine exhaust temperature reductions of about 100F can be achieved for each 1 lb/sec of powder injected. The emission spectra of materials and their reaction products are also discussed. (Author)