A Note on the Effects of Longitudinal Cyclic Pitch Control Variations on the Forced Aero‐Elastic Response of a Helicopter Rotor Blade

Abstract Active vibration control of helicopter rotor blade is studied. For the purpose of illustration, we have considered only flap wise vibration of a hingeless rotor blade, and modelled it, using finite element method, by 20 beam elements. The first 12 bending modes of the system are considered in the model. A H∞ controller is designed for the plant formulated as above. The result of the numerical simulation of the closed-loop system shows that the control introduces an appreciable amount of damping in the frequency region of interest. The consideration of the modelling uncertainty in the synthesis of the controller resulted in a design which is robust stable in presence of formulated model uncertainty.

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An Investigation of the Aerodynamic and Vibration Behavior of a Helicopter Rotor Blade

Volume 4: Advances in Aerospace Technology ◽

10.1115/imece2020-23668 ◽

2020 ◽

Author(s):

Mohammad Khairul Habib Pulok ◽

Uttam K. Chakravarty

Keyword(s):

Rotor Blade ◽

Fluid Structure Interaction ◽

Interaction Model ◽

Scale Model ◽

Helicopter Rotor ◽

Small Scale ◽

Fluid Structure ◽

Structure Interaction ◽

Aerodynamic Analysis ◽

Helicopter Rotor Blade

Abstract Rotary-wing aircrafts are the best-suited option in many cases for its vertical take-off and landing capacity, especially in any congested area, where a fixed-wing aircraft cannot perform. Rotor aerodynamic loading is the major reason behind helicopter vibration, therefore, determining the aerodynamic loadings are important. Coupling among aerodynamics and structural dynamics is involved in rotor blade design where the unsteady aerodynamic analysis is also imperative. In this study, a Bo 105 helicopter rotor blade is considered for computational aerodynamic analysis. A fluid-structure interaction model of the rotor blade with surrounding air is considered where the finite element model of the blade is coupled with the computational fluid dynamics model of the surrounding air. Aerodynamic coefficients, velocity profiles, and pressure profiles are analyzed from the fluid-structure interaction model. The resonance frequencies and mode shapes are also obtained by the computational method. A small-scale model of the rotor blade is manufactured, and experimental analysis of similar contemplation is conducted for the validation of the numerical results. Wind tunnel and vibration testing arrangements are used for the experimental validation of the aerodynamic and vibration characteristics by the small-scale rotor blade. The computational results show that the aerodynamic properties of the rotor blade vary with the change of angle of attack and natural frequency changes with mode number.

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Design optimization of helicopter rotor using kriging

Aircraft Engineering and Aerospace Technology ◽

10.1108/aeat-12-2016-0250 ◽

2018 ◽

Vol 90 (6) ◽

pp. 937-945 ◽

Cited By ~ 2

Author(s):

Saijal Kizhakke Kodakkattu ◽

Prabhakaran Nair ◽

Joy M.L.

Keyword(s):

Rotor Blade ◽

Optimization Problem ◽

Torsional Stiffness ◽

Helicopter Rotor ◽

Vibration Level ◽

Content Type ◽

Aeroelastic Analysis ◽

Kriging Metamodel ◽

Helicopter Rotor Blade ◽

Trailing Edge Flaps

Purpose The purpose of this study is to obtain optimum locations, peak deflection and chord of the twin trailing-edge flaps and optimum torsional stiffness of the helicopter rotor blade to minimize the vibration in the rotor hub with minimum requirement of flap control power. Design/methodology/approach Kriging metamodel with three-level five variable orthogonal array-based data points is used to decouple the optimization problem and actual aeroelastic analysis. Findings Some very good design solutions are obtained using this model. The best design point in minimizing vibration gives about 81 per cent reduction in the hub vibration with a penalization of increased flap power requirement, at normal cruise speed of rotor-craft flight. Practical implications One of the major challenges in the helicopters is the high vibration level in comparison with fixed wing aircraft. The reduction in vibration level in the helicopter improves passenger and crew comfort and reduces maintenance cost. Originality/value This paper presents design optimization of the helicopter rotor blade combining five design variables, such as the locations of twin trailing-edge flaps, peak deflection and flap chord and torsional stiffness of the rotor. Also, this study uses kriging metamodel to decouple the complex aeroelastic analysis and optimization problem.

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