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Brittle Materials Design, High Temperature Gas Turbine

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Final rept. 1 Jul 1971-31 Aug 1979

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A goal of 200 hours of engine of engine rig demonstrations for representative duty cycle temperatures in a regenerated vehicular gas turbine was chosen, with uncooled ceramic components to operate at least 25 hours at 2500 F, considerably beyond the temperatures possible with uncooled metal components. The total systems approach included major efforts in ceramic design, materials development, fabrication process development, and test and evaluation methodology. Considerable progress was made in each of these areas during the course of the program. For example, the strength of reaction bonded silicon nitride RBSN used in the stator and rotor blades was more than tripled between July 1971 and July 1977. By the end of the program, 200 hours of duty cycle durability on turbine test rigs between 1930 F - 2500 F was attained on RBSN stationary components including stators, nose cones and turbine rotor tip shrouds. Similarly, 200 hours of duty cycling on test rigs was attained with reaction sintered SiC combustors and stators. A 200 hour test of a duo-density silicon nitride rotor with 1800 F rim temperatures, with maximum blade temperatures of approximately 2200 F, was run at speeds to 50,000 rpm. Engine tests of up to 100 hours duration were run with an entire uncooled ceramic stationary flow path only the rotors being metallic at up to 87 of engine design speed at 1930 F. A 37 hours engine rig test was run with an uncooled ceramic rotor at temperatures up to 2500 F and speeds up to 50,000 RPM 100 Design E speed.

Subject Categories:

  • Ceramics, Refractories and Glass
  • Jet and Gas Turbine Engines

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