Investigation of rotor wake interactions in helicopters using 3d unsteady free vortex wake methodology

Yemenici, Öznur
This thesis focuses on developing and examining the capabilities of a new in-house aerodynamic analysis tool, AeroSIM+, and investigating rotor-rotor aerodynamic interactions for two helicopters, one behind the other in forward flight. AeroSIM+ is a 3-D unsteady vortex panel method potential flow solver based on a free vortex wake methodology. Validation of the results with the experimental data is performed using the Caradonna-Tung hovering rotor test case. AeroSIM+ code is improved for forward flight conditions so that, the blades are allowed to move according to the rotor dynamics. In the simulations, blade airload prediction is seen to be sensitive to changes in vortex core size. Blade Vortex Interaction (BVI) locations differ depending on the relative position of the rear rotor with respect to the front rotor as well as on the forward flight speed. It was observed that the performance characteristics of the rear rotor alter depending on the relative positions of the rotors within the asymmetric wake flow field. The results of this thesis study such as the computed forces and moments on each rotor and the frequency characteristics of these loads can be also used in helicopter dynamics simulators.


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In this study, design and analysis of a mode-switching vertical take-off and landing (VTOL) unmanned aerial vehicle (UAV) with level flight capability is considered. The design of the platform includes both multirotor and fixed-wing (FW) conventional airplane structures; therefore named as VTOL-FW. The aircraft is modeled using aerodynamical principles including post-stall conditions. Trim conditions are obtained by solving constrained optimization problems. Linear analysis techniques are utilized for trim ...
Design and analysis of a structural component of a heavy transport aircraft
Çıkrıkcı, Davut; Yaman, Yavuz; Department of Aerospace Engineering (2010)
This thesis aims to present the design and analysis of a structural component of a heavy transport aircraft. The designed component is the “coupling“ which is the interface member connecting two frames or two stringers in the fuselage assembly. The “frames”, which are the circumferential stiffeners, are joined together by the “frame couplings”. The “stringers”, which are the longitudinal stiffeners, are joined together by the “stringer couplings”. At the preliminary design phase; the structural design princ...
Development of a comprehensive and modular modelling, analysis and simulation tool for helicopters
Yücekayalı, Arda; Kutay, Ali Türker; Department of Aerospace Engineering (2011)
Helicopter flight dynamic, rotor aerodynamic and dynamic analyses activities have been a great dispute since the first helicopters, at both design and test stages. Predicting rotor aerodynamic and dynamic characteristics, helicopter dynamic behavior and trimmed flight conditions is a huge challenge to engineers as it involves the tradeoff between accuracy, fidelity, complexity and computational cost. Flight dynamic activities such as; predicting trim conditions, helicopter dynamic behavior and simulation of...
Accurate position control of a flapping-wing robot enabling free-flight flow visualisation in a wind tunnel
Karasek, Matej; Perçin, Mustafa; Cunis, Torbjorn; van Oudheusden, Bas W.; De Wagter, Christophe; Remes, Bart D. W.; de Croon, Guido C. H. E. (SAGE Publications, 2019-10-02)
Flow visualisations are essential to better understand the unsteady aerodynamics of flapping wing flight. The issues inherent to animal experiments, such as poor controllability and unnatural flapping when tethered, can be avoided by using robotic flyers that promise for a more systematic and repeatable methodology. Here, we present a new flapping-wing micro air vehicle (FWMAV)-specific control approach that, by employing an external motion tracking system, achieved autonomous wind tunnel flight with a maxi...
Simulation of Rapidly Maneuvering Airfoils with Synthetic Jet Actuators
Jee, SolKeun; Lopez Mejia, Omar D.; Moser, Robert D.; Muse, Jonathan A.; Kutay, Ali Türker; Calise, Anthony J. (American Institute of Aeronautics and Astronautics (AIAA), 2013-08-01)
Synthetic jet actuators are investigated for rapidly maneuvering airfoils that are regulated by a closed-loop control system. To support active flow-control simulations performed here, the closed-loop system and vehicle dynamics are coupled with computational fluid dynamics. High-frequency sinusoidal pitching simulations with and without synthetic jet actuation indicate that the current synthetic jet actuators provide bidirectional change in aerodynamic forces during rapid maneuvers whose time scales are of...
Citation Formats
Ö. Yemenici, “Investigation of rotor wake interactions in helicopters using 3d unsteady free vortex wake methodology,” M.S. - Master of Science, Middle East Technical University, 2010.