Aeroacoustic Noise Survey on Supersonic Transport Airframe in Large-Scale Aerodynamic Low-Speed Wind Tunnel

Abstract

To obtain aeroacoustic noise data and aerodynamic characteristics of airframe, SST configuration model was tested in closed test section of large-scale aerodynamic low-speed wind tunnel in JAXA. Size of the test section was 6.5m x 5.5m, and phased-array microphones were placed on upper wall of the closed test section. Noise source survey had been successfully conducted, and characteristics of typical noise sources on the airframe were visualized, such as noise from kink of double-delta wing, wing tip, landing gear, chine, and so on. Moreover, effects of the configuration and angle of attack and its frequency dependency were analyzed by comparing relative sound pressure level of maximum noise, and each element of noise sources was also investigated. In this testing, in large angle of attack, Cruise configuration showed noise in all frequency, and Landing (flap-down) configuration showed stronger noise in low frequency only. Gear configuration showed strong noise in low frequency in all angle of attack. In detailed analysis of noise source elements, in 4-10 kHz, dominant noise in large angle of attack in Cruise configuration was kink of main wing, and gear noise was remarkable at low angle of attack in Gear configuration. Wing tip noise also became large at medium angle of attack in Landing configuration. At 16 kHz, the kink noise was still strong, but gear noise was not visible very much. Mechanism of noise occurrence was also discussed using these characteristics.