Helicopter blade flapping with and without small angle assumption in the presence of dynamic stall

Majhi, Jyoti Ranjan and Ganguli, Ranjan (2010) Helicopter blade flapping with and without small angle assumption in the presence of dynamic stall. In: Applied Mathematical Modelling, 34 (12). pp. 3726-3740.

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Abstract

The flapping equation for a rotating rigid helicopter blade is typically derived by considering (1)small flap angle, (2) small induced angle of attack and (3) linear aerodynamics. However, the use of nonlinear aerodynamics such as dynamic stall can make the assumptions of small angles suspect as shown in this paper. A general equation describing helicopter blade flap dynamics for large flap angle and large induced inflow angle of attack is derived. A semi-empirical dynamic stall aerodynamics model (ONERA model) is used. Numerical simulations are performed by solving the nonlinear flapping ordinary differential equation for steady state conditions and the validity of the small angle approximations are examined. It is shown that the small flapping assumption, and to a lesser extent, the small induced angle ofattack assumption, can lead to inaccurate predictions of the blade flap response in certain flight conditions for some rotors when nonlinear aerodynamics is considered. (C) 2010 Elsevier Inc. All rights reserved.

Item Type:	Journal Article
Publication:	Applied Mathematical Modelling
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Helicopter;Flapping;Aerodynamics;Dynamic stall;Aeroelasticity
Department/Centre:	Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited:	24 Aug 2010 06:41
Last Modified:	19 Sep 2010 06:14
URI:	http://eprints.iisc.ac.in/id/eprint/31344

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