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Interactional aerodynamics and acoustics of a hingeless coaxial helicopter with an auxiliary propeller in forward flight

Published online by Cambridge University Press:  03 February 2016

H. W. Kim ,
A. R. Kenyon ,
R. E. Brown  and
K. Duraisamy
H. W. Kim
Affiliation:
[email protected], Department of Aeronautics, Imperial College London, London, UK
A. R. Kenyon
Affiliation:
[email protected]
R. E. Brown
Affiliation:
[email protected], Department of Aerospace Engineering, University of Glasgow, Glasgow, UK
K. Duraisamy
Affiliation:
[email protected]
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Abstract

The aerodynamics and acoustics of a generic coaxial helicopter with a stiff main rotor system and a tail-mounted propulsor are investigated using Brown’s Vorticity Transport Model. In particular, the model is used to capture the aerodynamic interactions that arise between the various components of the configuration. By comparing the aerodynamics of the full configuration of the helicopter to the aerodynamics of various combinations of its sub-components, the influence of these aerodynamic interactions on the behaviour of the system can be isolated. Many of the interactions follow a simple relationship between cause and effect. For instance, ingestion of the main rotor wake produces a direct effect on the unsteadiness in the thrust produced by the propulsor. The causal relationship for other interdependencies within the system is found to be more obscure. For instance, a dependence of the acoustic signature of the aircraft on the tailplane design originates in the changes in loading on the main rotor that arise from the requirement to trim the load on the tailplane that is induced by its interaction with the main rotor wake. The traditional approach to the analysis of interactional effects on the performance of the helicopter relies on characterising the system in terms of a network of possible interactions between the separate components of its configuration. This approach, although conceptually appealing, may obscure the closed-loop nature of some of the aerodynamic interactions within the helicopter system. It is suggested that modern numerical simulation techniques may be ready to supplant any overt reliance on this reductionist type approach and hence may help to forestall future repetition of the long history of unforeseen, interaction-induced dynamic problems that have arisen in various new helicopter designs.

Type
Research Article
Information
The Aeronautical Journal , Volume 113 , Issue 1140: The International Powered Lift Conference 2008: A Special issue , February 2009 , pp. 65 - 78
Copyright
Copyright © Royal Aeronautical Society 2009 

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