Mechanism and control of airframe noise of large passenger aircraft

The aerodynamic noise is not only the key problem of airworthiness forensics of large airliners, but also an important index related to passenger comfort. High lift device noise and landing gear noise are the main sources of airframe noise. In this paper, the key problems of the noise mechanism and control of the noise high lift device and landing gear in the development of large passenger aircraft are studied. In view of the noise generation mechanism, a novel noise source analysis method is proposed for vortex dynamics processes such as vorticity near wall boundary and boundary vorticity flux. Aiming at the noise control of the airframe, the small-scale wavy control method of the slat wing cove and large-scale wavy control method of landing gear support strut are proposed. The numerical results show that the slat cove is the main noise source of the high lift devices. The noise and pure tone peaks of the low and middle frequencies are mainly from the slat cove and the leading edge of the main wing, and the trailing edge flap makes a relatively small contribution to the noise. A large number of complex large-scale turbulent vortex structures exist in the wake region of the landing gear and the cove region of wheels, which are the main noise source of the landing gear. The noise characteristics of each landing gear component basically exhibit broadband characteristics. The strut component has the largest radiation noise, and the axle and torque link components have relatively small radiation noise. The slat cove wavy noise control method has both drag reduction and noise reduction effects. The large-scale wavy noise control method of the landing gear can reduce the far-field radiation noise effectively. The research content of this paper provides technical support for the integrated pneumatic and noise design of high lift device and noise reduction design of the landing gear.