UNSTEADY LIFTING-LINE THEORY AS A SINGULAR-PERTURBATION PROBLEM.

被引：0

作者：

Ahmadi, Ali R. ^{[1
]}

Widnall, Sheila E. ^{[1
]}

机构：

[1] MIT, Cambridge, MA, USA, MIT, Cambridge, MA, USA

来源：

Journal of Fluid Mechanics | 1985年 / 153卷

关键词：

FLOW OF FLUIDS - Unsteady Flow;

D O I：

暂无

中图分类号：

V211 [空气动力学]; V411 [空气动力学];

学科分类号：

0801 ; 080103 ; 080104 ;

摘要：

Unsteady lifting-line theory is developed for a wing of large aspect ratio oscillating at low frequency in inviscid incompressible flow. The wing is assumed to have a rigid chord but a flexible span. Use of the method of matched asymptotic expansions reduces the problem from a singular integral equation to quadrature. The pressure field and airloads, for a prescribed wing shape and motion, are obtained in closed form as expansions in inverse aspect ratio. A rigorous definition of unsteady induced downwash is also obtained. Numerical calculations are presented for an elliptic wing in pitch and heave; compared with numerical lifting-surface theory, computation time is reduced significantly. The present work also identifies and resolves errors in the unsteady lifting-line theory of E. C. James, and points out a limitation in that of T. van Holten. Refs.

引用

页码：59 / 81