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Laplace-domain approximation to the transfer functions of a rotor blade in forward flight

Published online by Cambridge University Press:  04 July 2016

F. Nitzsche
F. Nitzsche*
Affiliation:
Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa, Ontario, Canada
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Abstract

A continuous frequency domain method with roots on the classic Hill’s determinant analysis is presented to approximate the time-varying characteristics of a linear periodic system. The method is particularly useful to derive a time-invariant equivalent form of the time-varying aeroelastic problem of a rotor blade in forward flight. The proposed technique allows methodology usually employed in fixed wing aircraft to obtain closed-loop control laws be extended to rotary wings. The method is first validated solving Mathieu’s equation. Next, the two-degree-of-freedom (flap bending and torsion) problem of rotating beam subject to unsteady and incompressible aerodynamics in forward flight is solved in the laplace domain. As a demonstration of the proposed method, the transfer functions in the ‘s’ plane between a sudden and uniformly distributed input pressure perturbation applied along the beam and the output response of the two elastic degrees of freedom considered are obtained at a set of local sections.

Type
Research Article
Information
The Aeronautical Journal , Volume 105 , Issue 1047 , April 2001 , pp. 233 - 240
Copyright
Copyright © Royal Aeronautical Society 2002 

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