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An asymptotic unsteady lifting-line theory with energetics and optimum motion of thrust-producing lifting surfacesA low frequency unsteady lifting-line theory is developed for a harmonically oscillating wing of large aspect ratio. The wing is assumed to be chordwise rigid but completely flexible in the span direction. The theory is developed by use of the method of matched asymptotic expansions which reduces the problem from a singular integral equation to quadrature. The wing displacements are prescribed and the pressure field, airloads, and unsteady induced downwash are obtained in closed form. The influence of reduced frequency, aspect ratio, planform shape, and mode of oscillation on wing aerodynamics is demonstrated through numerical examples. Compared with lifting-surface theory, computation time is reduced significantly. Using the present theory, the energetic quantities associated with the propulsive performance of a finite wing oscillating in combined pitch and heave are obtained in closed form. Numerical examples are presented for an elliptic wing.
Document ID
19810014502
Acquisition Source
Legacy CDMS
Document Type
Thesis/Dissertation
Authors
Ahmadi, A. R. (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
September 4, 2013
Publication Date
April 1, 1981
Subject Category
Aerodynamics
Report/Patent Number
NASA-CR-165679
Accession Number
81N23035
Funding Number(s)
CONTRACT_GRANT: NGR-22-009-818
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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