Study and Demonstration of Passively Cooled Nozzles Containing Heat Absorbent Coolants Between Pyrolytic Graphite Washers

摘要

When utilizing passively cooled rocket assemblies, the onset of chemical corrosion can become a significant problem. At the elevated temperatures experienced in the combustion of halogenated oxidizers with amine fuels, chemical corrosion becomes a significant problem due to the accelerated reaction rates between the corrosive exhaust species and the inner rocket wall. The excessive removal of the wall and throat material may cause unpredictable and unacceptable fluctuations in delivered thrust of rocket engines. This program's objective was to investigate the utility of internally contained heat absorbent coolants in lowering the throat wall temperature of pyrolytic graphite washer nozzle inserts, and the subsequent minimizing of the amount of chemical corrosion in the throat. Analytical investigation of this concept revealed that nozzles containing heat absorbent coolants would be most effective in reducing throat erosion when fired for long duration (1000 seconds) at chamber pressures below 500 psia. Three pyrolytic graphite nozzles were designed and fabricated for test evaluation at 200 psia chamber pressure with liquid fluorine/amine propellants. Two of the nozzles contained internal coolants, the third being a heat sink nozzle without coolants for comparison purposes. (Author)