111 非コンパクトグリーン関数による楕円翼の低騒音設計 : マシュー関数の応用(騒音・振動の解析技術(2))

抄録

This paper describes a new method of designing low noise wing using Non-compact Green function represented by Mathieu function. The author stands for the theory of vortex sound for predicting wing noise from low Mach number flow, where the Green function represents the acoustical boundary condition. 'Compact Green function' has been developed for predicting the wing noise, whose usability is confined within low frequency range. On the contrary the new Non- compact Green function is feasible on high frequency range, since the function satisfies the Helmholtz equation in place of the Laplace equation. Mathieu function is introduced to represents the boundary condition of wing-like flat cylindrical body. Boundary condition of porous surface is considered to compose the Green function. Two cases are presented for designing method of low flow noise body, firstly a circular cylinder and secondly the slender 2-D wing. This paper presents designing examples of low-noise wing with porous surface.