A compact apparatus for simulating the in-flight aerodynamic performance of a multimission aircraft propulsion system of the gas turbine engine variety having an external envelope of a reduced size in relation to the engine to be simulated. The apparatus includes a turbine driven by externally generated, high pressure motive air which is drivingly connected to a compressor in the usual manner of a gas turbine engine. The flow of air pressurized by the compressor is mixed with a portion of the relatively higher pressure turbine motive air so as to generate a mixed flow having a generally uniform pressure profile entering the exhaust nozzle. The compressor, turbine, mixer and nozzle are sized to produce a pressure ratio across the apparatus and a nozzle flow function which are substantially identical to the engine to be simulated, though these components are of a reduced size in relation thereto. Through modulation of the amount of turbine motive air which is mixed with the air pressurized by the compressor, the nozzle flow function and pressure ratio can be altered to simulate a wide range of engine operating cycles including those associated with reheat and dry operation. The remainder of the turbine motive air exhausts from the apparatus as a nonpropulsive stream.
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