Aeroacoustic Validation of Installed Low Noise Propulsion for NASA's N+2 Supersonic Airliner

Bridges, James

关键词: AEROACOUSTICS;    ACOUSTIC MEASUREMENT;    SYSTEMS INTEGRATION;    LOW NOISE;    PROPULSION;    FAR FIELDS;    TRANSPORT AIRCRAFT;    DIRECTIVITY;    PHASED ARRAYS;    JET AIRCRAFT NOISE;    PROPULSION SYSTEM CONFIGURATIONS;    INSTALLING;    NOISE PREDICTION;    REGULATIONS;    CERTIFICATION;   

RP-ID  :  GRC-E-DAA-TN50110

美国|英语

来源: NASA Technical Reports Server

【 摘 要 】

An aeroacoustic test was conducted at NASA Glenn Research Center on an integrated propulsion system designed to meet noise regulations of ICAO Chapter 4 with 10EPNdB cumulative margin. The test had two objectives: to demonstrate that the aircraft design did meet the noise goal, and to validate the acoustic design tools used in the design. Variations in the propulsion system design and its installation were tested and the results compared against predictions. Far-field arrays of microphones measured the acoustic spectral directivity, which was transformed to full scale as noise certification levels. Phased array measurements confirmed that the shielding of the installation model adequately simulated the full aircraft and provided data for validating RANS-based noise prediction tools. Particle image velocimetry confirmed that the flow field around the nozzle on the jet rig mimicked that of the full aircraft and produced flow data to validate the RANS solutions used in the noise predictions. The far-field acoustic measurements confirmed the empirical predictions for the noise. Results provided here detail the steps taken to ensure accuracy of the measurements and give insights into the physics of exhaust noise from installed propulsion systems in future supersonic vehicles.