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Advances in aircraft performance depend heavily upon improved and properly integrated propulsion systems. Historically, new engines and aircraft are developed concurrently, but the design and test cycle of engine systems is longer than that of the aircraft they power because of demanding flight qualification, reliability, and durability requirements 1 . Consequently, the engine hardware development process starts first, so that the success of the entire program often hinges on engine design decisions made early in the process. Critical to the design of efficient air vehicle systems is the design of the gas turbine exhaust nozzle. Aircraft exhaust nozzles serve two primary functions. First, they must control the engine backpressure to provide the correct, and optimum, engine performance, which is accomplished through jet area variations. Second, they must efficiently convert the potential energy of the exhausting gas to kinetic energy by increasing the exhaust velocity, which is accomplished through efficiently expanding the exhausting gases to the ambient pressure. Since the exhaust nozzle provides the integration between the propulsion and aircraft systems, its design must also consider installed, or thrust-minus-drag, performance. Additional design challenges are introduced by the requirement for features such as thrust vectoring and reversing. This paper provides guidelines and procedures for incorporating these considerations into the design of gas turbine exhaust nozzles. NOMENCLATURE |
