COMBINED CYCLE ENGINE VARIABLE AREA NOZZLE DEVELOPMENT

High speed combined cycle propulsion systems have several subsystems in common including the need for a method through which the exhaust nozzle area can be varied to meet the range of altitudes and velocities within a given systems' flight envelope. The extremely high temperatures and limited material cooling media available for advanced engine systems combined with lightweight propulsion system needs makes the use of high temperature composite materials, ceramic matrix composites, (CMC's) very attractive for extreme temperatures and demanding performance conditions that a variable area nozzle must meet. The required mechanical motions of a variable area nozzle makes the development of ultra high temperature lubricant systems extremely important to the reliable function of a CMC variable area nozzle. Ceramic Composites, Inc. has proposed a Phase I demonstration experiment that addresses key CMC and lubricant or tribological performance issues. Ho pivoting nozzle component tests at temperatures up to 1500 degrees C will be performed in an existing ceramic kiln to demonstrate feasibility of a hot CMC variable area nozzle. Phase II will address complete variable area nozzle design and various subcomponent development activities which will lead up a connected pipe engine test with a prototype variable area nozzle.