Analysis and design of helicopter rotor blades for reduced vibrational level

Download
2011
Tamer, Aykut
In this thesis analysis and design of helicopter rotor blades were discussed for reduced vibrational level. For this purpose an optimization procedure was developed which involves coupling of the comprehensive rotorcraft analysis tool CAMRAD JA and the gradient based optimization algorithm. The main goal was to achieve favorable blade structural dynamics characteristics that would lead to reduction in vibrational level. For this purpose blade stiffness and mass distributions were considered as the design variables. In order to avoid likely occurrences of unrealistic results, the analyses were subjected to constraints which were sensitive to the design variables. The optimization procedure was applied on two isolated rotor blades and a full helicopter with main rotor, tail rotor and fuselage by using natural frequency separation and hub load minimization respectively. While the former approach relied on the blade natural frequencies, the latter approach involved higher harmonic aerodynamic and blade motion calculations. For both approaches, the improvement in vibration characteristics and blade mass and stiffness distributions of the initial design and the design after optimization analyses were compared and discussed.

Suggestions

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...
Design and analysis of an equipment rack structure of a medium transport aircraft
Yalçın, Mehmet Efruz; Yaman, Yavuz; Department of Aerospace Engineering (2009)
In this study, equipment rack structure for a medium transport aircraft was designed and finite element analysis of this design was performed. The equipment rack structure, which was designed for a modernization project, was positioned and dimensions were determined by regarding the geometry of primary structures of the aircraft. The structure was designed such that it satisfies the pre-defined margin of safety values. Design of the structure was prepared in Unigraphics, and the finite element modeling and ...
Investigation of rotor wake interactions in helicopters using 3d unsteady free vortex wake methodology
Yemenici, Öznur; Uzol, Oğuz; Department of Aerospace Engineering (2010)
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 cond...
Adaptive controller applications for rotary wing aircraft models of varying simulation fidelity
Tarımcı, Onur; Yavrucuk, İlkay; Department of Aerospace Engineering (2009)
This thesis concerns the design, analysis and testing of adaptive controllers for rotary wing aircraft, in particular helicopters. A non-linear helicopter model is developed and validated by trim and dynamic response analyses. A inner-outer loop cascade controller is designed with a trajectory generator in the most outer layer and an adaptive neural network controller is implemented to the inner loop. Controller is then challenged to carry out complex maneuvers autonomously under turbulence. Finally, the ce...
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...
Citation Formats
A. Tamer, “Analysis and design of helicopter rotor blades for reduced vibrational level,” M.S. - Master of Science, Middle East Technical University, 2011.