Accession Number : ADA307817

Title :   Experimental Evaluation of Throat Inserts in a Storable-Propellant Rocket Engine.

Descriptive Note : Technical memo.,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER

Personal Author(s) : Winter, Jerry M. ; Plews, Larry D. ; Johnston, James R.

PDF Url : ADA307817

Report Date : OCT 1966

Pagination or Media Count : 99

Abstract : A total of 57 throat inserts for ablative-material nozzle sections were tested at a nominal throat diameter of 1.20 inches. The two propellants used were nitrogen tetroxide and a blend of 50 percent hydrazine and 50 percent unsymmetrical dimethyl hydrazine. Nominal engine conditions included a chamber pressure of 100 pounds per square inch absolute and an oxidant-fuel ratio of 2.0. The materials tested ranged from ablative-reinforced plastics to refractory alloys. No throat erosion, low outer envelope temperature, and structural integrity were the criteria for an acceptable insert. Hypereutectic zirconium carbide met these criteria after two 60-second firing cycles. Refractory metals such as tungsten and molybdenum were found to oxidize rapidly in the test environment. The refractory oxides provided good erosion resistance but suffered thermal shock failures. Pyrolytic graphite gave encouraging results but requires further design work. The best insert was a 0.040-inch-thick pyrolytic silicon carbide coating on graphite, which underwent four test cycles totalling 722 seconds before failure.

Descriptors :   *NOZZLE THROATS, *STORABLE ROCKET PROPELLANTS, TEST AND EVALUATION, METALS, LOW TEMPERATURE, HYDRAZINES, DIMETHYLHYDRAZINES, GRAPHITE, MOLYBDENUM, CARBIDES, CYCLES, EROSION, PRESSURE, ZIRCONIUM, ENVIRONMENTAL TESTS, EXTERNAL, NITROGEN OXIDES, TUNGSTEN, ENVELOPE(SPACE), CHAMBERS, REFRACTORY MATERIALS, PYROLYTIC GRAPHITE, EROSION RESISTANCE, THROATS(EQUIPMENT), INSERTS, EUTECTICS, REFRACTORY METAL ALLOYS, TETROXIDES, STRUCTURAL INTEGRITY.

Subject Categories : Liquid Rocket Propellants

Distribution Statement : APPROVED FOR PUBLIC RELEASE