关键词: 剪刀式尾桨, 气动特性, 噪声特性, FW-H方程, 计算流体力学

Abstract:

A comprehensive analysis method is established to predict the aerodynamic force and aeroacoustic characteristics of a scissors tail-rotor in hover based on computational fluid dynamics (CFD)/FW-H (Ffowcs Williams-Hawkings). In the present method, the CFD method is first employed to simulate the flowfield around the tail-rotor by solving the Reynolds-averaged Navier-Stokes equations which are formulated at the blade-attached reference frame, and a second-order upwind scheme (Roe scheme) and an implicit LU-SGS (Lower-Upper Symmetric Gauss-Seidel) scheme are used for space and time discretization respectively. Secondly, based on the flowfield solved by the present CFD method, the FW-H equation is used to transfer acoustic disturbance to the far field. Finally, comprehensive calculations on two different configurations of scissors tail-rotor, i.e., L configuration and U configuration, are performed based on the method developed. The differences are studied between a scissors tail-rotor and a conventional tail-rotor in terms of aerodynamic force and aeroacoustic characteristics. Meanwhile, the influence is analyzed of the two important parameters of scissors angle and vertical space on the aerodynamic force and acoustic characteristics. It is demonstrated that the configuration parameters have significant effects on the aerodynamic force and aeroacoustic characteristics of the tail-rotor, and reasonable configuration parameters can decrease its acoustic level.

Key words: scissors tail-rotor, aerodynamic performance, aeroacoustic characteristic, FW-H equation, computational fluid dynamics