Jet Diffuser for Simulating Ram-Pressure and Altitude Conditions on a Turbojet-Engine Static Test Stand

An investigation has been made of an experimental jet diffuser designed to utilize the kinetic energy of the jet from a turbojet engine to reduce the discharge pressure at the exhaust nozzle, and thereby to provide simulated ram-pressure ratios across the engine and altitudes. Curves of performance data for a turbojet engine at several ram-pressure ratios across the engine and altitudes. Curves of performance data for a turbojet engine at several ram-pressure ratios show the range of engine operating conditions obtainable with the jet diffuser. A maximum engine-inlet to exhaust-chamber pressure ratio of about 2.4 was obtained at a simulated pressure altitude of approximately 23,000 feet. Comparison of the engine thrust obtained at a ram-pressure ratio of 1.0 with and without the jet diffuser, indicated that the presence of the diffuser did not interfere with the gas flow through the engine-exhaust-nozzle outlet at this ram-pressure ratio and at a ram-pressure ratio greater than 1.0.