High Chamber Pressure Reusable Rocket Engine Technology 700798
Performance and extended component life are key requirements of propulsion for reusable launch craft (the space shuttle). Performance of the engine and vehicle require engines with high expansion ratio nozzles in compact sizes. The combination of thrust, specific impulse, and engine envelope required for the space shuttle can be achieved with a 3000-psia chamber pressure rocket engine. Pumping the propellants to high pressures requires high turbopump horsepower, dictating a staged combustion rocket engine cycle to eliminate the thrust performance loss associated with propellants that are used to drive the turbopumps. High energy density engines have much higher heat fluxes, turbomachinery speeds and mechanical stress than prior generations of rocket engines requiring more sophisticated design methods and mechanical configuration to meet the performance objectives. The reuse requirements place new restrictions on the design of rocket engines, particularly in the hot section areas where low cycle fatigue (LCF) and material creep properties determine life and cyclic limits. Design procedures and criteria that are being used for the design of Pratt & Whitney Aircraft's reusable shuttle rocket engine are based on those that have been used successfully for the design of commercial and military turbojet engines. This paper discusses significant components and features of design that give lightweight highly stressed parts extended component life.