摘要
Flap side-edge noise is a significant noise source for airplane at takeoff and landing stages. The generation mechanism of flap side-edge noise is analyzed by numerical simulation on unsteady flow field using Very Large Eddy Simulation （VLES）. Two kinds of flap side-edge shape modifications are proposed, and their frequency spectrum and directivity of far-field noise are compared with the baseline configuration using permeable integral surface Ffowcs Williams and Hawkings （FW-H） acoustic analogy method to investigate their effects on noise reduction. Via the numerical simulation of flow field and acoustic field, it proves that the flap side-edge noise is broadband noise in nature. The different shapes of flap side-edge change the pattern of flow field, vortex structures and the development of vortex, thus having influences on noise source distributions and characteristics of far-field noise. The result shows that at the given 5° angle of attack, the proposed flap side-edge shape modifications can reduce the overall sound pressure level （OASPL） by 1 to 2 dB without decreasing the lift and drag aerodynamic performances.
Flap side-edge noise is a significant noise source for airplane at takeoff and landing stages. The generation mechanism of flap side-edge noise is analyzed by numerical simulation on unsteady flow field using Very Large Eddy Simulation （VLES）. Two kinds of flap side-edge shape modifications are proposed, and their frequency spectrum and directivity of far-field noise are compared with the baseline configuration using permeable integral surface Ffowcs Williams and Hawkings （FW-H） acoustic analogy method to investigate their effects on noise reduction. Via the numerical simulation of flow field and acoustic field, it proves that the flap side-edge noise is broadband noise in nature. The different shapes of flap side-edge change the pattern of flow field, vortex structures and the development of vortex, thus having influences on noise source distributions and characteristics of far-field noise. The result shows that at the given 5° angle of attack, the proposed flap side-edge shape modifications can reduce the overall sound pressure level （OASPL） by 1 to 2 dB without decreasing the lift and drag aerodynamic performances.
