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Modeling of iced rotor dynamics via CFD/CSD coupling

Wagdi G. Habashi (Department of Mechanical Engineering, McGill University, Montreal, Canada)
Maged Yassin (Department of Mechanical Engineering, McGill University, Montreal, Canada)

International Journal of Numerical Methods for Heat & Fluid Flow

ISSN: 0961-5539

Article publication date: 5 May 2022

Issue publication date: 25 November 2022




The purpose of this paper is to advance the multiphysics analysis of helicopter rotors under icing conditions by coupling the iced rotor’s aerodynamics, analyzed by CFD, with the rotor’s structural characteristics, analyzed by CSD.


The current work introduces supercomputer-based computational approaches capable of assessing the impact of ice accretion on the aerodynamics, blade dynamics, vibrations and loading of a rotorcraft. The rigid and elastic motions of the blades are accounted for through a loose coupling of the flow solver to a multibody dynamics solver. The coupling framework allows for comprehensive aeroelastic simulations of iced rotors in hover and in forward flight.


The flow and structural modules were validated on a full helicopter configuration in forward flight using the ROBIN experimental model. The tip structural deflections were in very close agreement with the experimental measurements.

Research limitations/implications

The results of the CFD analyses are limited by the available experimental results they can be compared to. In dry air CFD, three-dimensional (3D) experiments occur first and CFD is then compared to them; in icing, the opposite is true: 3D experiments (if they are ever done, as they are very expensive) chase CFD and sometimes never occur.

Practical implications

This paper presents an outline of how CFD and computational stress dynamics (CSD) analyses can be linked and provides a toolbox for deeper investigation of the complex flows over helicopters operating under difficult in-flight icing conditions.

Social implications

More and more helicopters are designed to be able to operate in hostile environments such as rescuing and saving lives over the oceans or mountains, conditions under which icing encounters cannot be avoided.


A loosely coupled CFD/CSD framework that accounts for the rotor blades structural response to aerodynamic loading and ice accretion in hover and forward flight has been presented. This versatile and cost-effective framework provides a more accurate estimation of the helicopter rotor performance and its degradation due to icing encounters during the early design stages than traditional CFD tools.



The authors are grateful for the generous financial support of the Natural Sciences and Engineering Research Council of Canada (NSERC) and Bell in the form of an NSERC-Industrial Research Chair. The authors are also grateful to the Digital Research Alliance of Canada for the use of their supercomputer resources. Finally, the authors would like to acknowledge Professor Pierangelo Masarati for his assistance and advice with regards to helicopter aerodynamics and multibody modeling and access to MBDyn.


Habashi, W.G. and Yassin, M. (2022), "Modeling of iced rotor dynamics via CFD/CSD coupling", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 32 No. 12, pp. 3848-3862.



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