Scale-Model, Low-Tip-Speed Turbofan Tested at Simulated Takeoff and Approach Conditions

Low-tip-speed fan installed in wind tunnel.

The test rig simulates full-scale engine components in scale-model size. The complete engine fan module (engine nacelle, bypass fan stage, and nozzle), a throughflow core duct, and engine acoustic treatment within the nacelle are all simulated. During the testing, fan model performance is obtained from force balances mounted internally in the model as well as by airflow measurements taken with duct wall and rake instrumentation. The internal force balances consist of a two-component rotating balance to measure thrust and torque and a six-component static balance to measure the drag and torque forces of the bypass stator and nacelle. Far-field acoustic measurements are obtained by a track-mounted, axially translating microphone. The microphone makes equal-angle stops along the traverse to obtain the noise at simulated takeoff and approach conditions. A rotating microphone array is used in the inlet and exhaust to obtain induct noise measurements for source diagnostic research.

The data obtained during this test will be used by NASA and Pratt & Whitney research engineers to ascertain the benefits of this lower tip speed, high-bypass-ratio fan stage. They will validate computer design and analysis codes used for both fan stage components and acoustic treatment. Comparison of the data with predictions from the computer codes will indicate where these codes can be improved for better performance predictions, lower noise, and better engine designs.