Experimental Slat Noise Assessment Through Phased Array and Hot-Film Anemometry Measurements

摘要

Slat acoustic and aerodynamic properties are investigated through experimental tests in a wind tunnel. Far held acoustic measurements using microphone phased array are performed along with hot-film anemometry to assess slat noise mechanisms, specially mid-frequency slat tones. The high-lift model is representative of a conventional commercial aircraft, with slotted slats and single flap. The acoustically treated closed test section wind tunnel used for the campaign withstand velocities up to 40 m/s and, by means of a suction system at the walls, can represent high-lift two-dimensional flow. Acoustic measurements are carried out with a 61 microphone array and results are processed through frequency domain Conventional Beamforming technique with source power integration for acoustic source localization and spectral analysis. Hot-film anemometry is used in slat cove region close to the reattachment location, distributed both in chordwise and spanwise directions. A single probe at the slat cusp is used for analysis of the tripping effects and of the flow characteristics emerging from the cusp. The model set-up is analyzed considering wind tunnel wall suction, slat brackets effects, and influence of trip on slat pressure side. Three different tripping devices are tested and results are evaluated according to its aerodynamic and aeroacoustic influences. Results provide acoustic and aerodynamic characterization of the model slat noise sources along with detailed information about broadband noise and mid-frequency peaks, which include reattachment localization, spectral analysis, and correlation between aerodynamic unsteadiness and far field mapped noise sources.