scholarly journals Helicopter Vibratory Loads Alleviation through Combined Action of Trailing-Edge Flap and Variable-Stiffness Devices

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Massimo Gennaretti ◽  
Giovanni Bernardini ◽  
Jacopo Serafini ◽  
Marco Molica Colella
Keyword(s):  
Rotor Blade ◽  
Variable Stiffness ◽  
Control Procedure ◽  
Trailing Edge ◽  
Control Effort ◽  
Control Laws ◽  
Trailing Edge Flaps ◽  
Control Configuration ◽  
Helicopter Main Rotor ◽  
And Control

The aim of this paper is the assessment of the capability of controllers based on the combined actuation of flaps and variable-stiffness devices to alleviate helicopter main rotor vibratory hub loads. Trailing-edge flaps are positioned at the rotor blade tip region, whereas variable-stiffness devices are located at the pitch link and at the blade root. Control laws are derived by an optimal control procedure based on the best trade-off between control effectiveness and control effort, under the constraint of satisfaction of the equations governing rotor blade aeroelastic response. The numerical investigation concerns the analysis of performance and robustness of the control techniques developed, through application to a four-bladed helicopter rotor in level flight. The identification of the most efficient control configuration is also attempted.

Induced-shear piezoelectric actuators for rotor blade trailing edge flaps

2002 ◽  
Vol 11 (1) ◽  
pp. 24-35 ◽  
Author(s):  
Louis R Centolanza ◽  
Edward C Smith ◽  
Brian Munsky
Keyword(s):  
Rotor Blade ◽  
Piezoelectric Actuators ◽  
Trailing Edge ◽  
Trailing Edge Flaps

Vibration reduction of helicopter with trailing-edge flaps at various flying conditions

2016 ◽  
Vol 231 (4) ◽  
pp. 770-784 ◽  
Author(s):  
SK Kodakkattu ◽  
ML Joy ◽  
K Prabhakaran Nair
Keyword(s):  
Rotor Blade ◽  
Torsional Stiffness ◽  
Trailing Edge ◽  
Control Power ◽  
Surface Method ◽  
Solidity Ratio ◽  
Helicopter Rotor Blade ◽  
Trailing Edge Flaps ◽  
Trailing Edge Flap ◽  
Improved Design

The aim of this study is to find the optimal torsional stiffness and trailing-edge flap locations of the helicopter rotor blade for minimum vibration and flap control power at flap lengths of 6% and 9% of the rotor-blade length. A three level orthogonal array based response surface method using polynomial functions is used to describe both vibration and flap control power. Pareto points minimizing hub vibration and flap control power are found at flap lengths of 6% and 9% of the rotor length. This study also explores the variation in rotor hub vibration and flap control power with flying conditions such as the advance ratio and the thrust-to-solidity ratio at the optimum design points. This gives a useful improved design with about a 60% decrease in hub vibration with a penalization of increased flap power at the normal flying regime of rotor-craft flight.

Sizing and control of trailing edge flaps on a smart rotor for maximum power generation in low fatigue wind regimes

Wind Energy ◽  
2015 ◽  
Vol 19 (4) ◽  
pp. 607-624 ◽  
Author(s):  
Jeroen Smit ◽  
Lars O. Bernhammer ◽  
Sachin T. Navalkar ◽  
Leonardo Bergami ◽  
Mac Gaunaa
Keyword(s):  
Power Generation ◽  
Maximum Power ◽  
Trailing Edge ◽  
Trailing Edge Flaps ◽  
Wind Regimes ◽  
And Control

scholarly journals Identification of Flap Motion Parameters for Vibration Reduction in Helicopter Rotors with Multiple Active Trailing Edge Flaps

2011 ◽  
Vol 18 (5) ◽  
pp. 727-745 ◽  
Author(s):  
Uğbreve;ur Dalli ◽  
Şcedilefaatdin Yüksel
Keyword(s):  
Rotor Blade ◽  
Helicopter Rotor ◽  
System Response ◽  
Trailing Edge ◽  
Blade Root ◽  
Helicopter Rotor Blade ◽  
Blade Vibrations ◽  
Trailing Edge Flaps ◽  
Trailing Edge Flap ◽  
Blade Loads

An active control method utilizing the multiple trailing edge flap configuration for rotorcraft vibration suppression and blade loads control is presented. A comprehensive model for rotor blade with active trailing edge flaps is used to calculate the vibration characteristics, natural frequencies and mode shapes of any complex composite helicopter rotor blade. A computer program is developed to calculate the system response, rotor blade root forces and moments under aerodynamic forcing conditions. Rotor blade system response is calculated using the proposed solution method and the developed program depending on any structural and aerodynamic properties of rotor blades, structural properties of trailing edge flaps and properties of trailing edge flap actuator inputs. Rotor blade loads are determined first on a nominal rotor blade without multiple active trailing edge flaps and then the effects of the active flap motions on the existing rotor blade loads are investigated. Multiple active trailing edge flaps are controlled by using open loop controllers to identify the effects of the actuator signal output properties such as frequency, amplitude and phase on the system response. Effects of using multiple trailing edge flaps on controlling rotor blade vibrations are investigated and some design criteria are determined for the design of trailing edge flap controller that will provide actuator signal outputs to minimize the rotor blade root loads. It is calculated that using the developed active trailing edge rotor blade model, helicopter rotor blade vibrations can be reduced up to 36% of the nominal rotor blade vibrations.

AEROELASTIC ANALYSIS OF BEARINGLESS ROTOR SYSTEMS WITH TRAILING EDGE FLAPS

2009 ◽  
Vol 23 (03) ◽  
pp. 461-464
Author(s):  
IN-GYU LIM ◽  
IN LEE
Keyword(s):  
Control Process ◽  
Beam Theory ◽  
Forward Flight ◽  
Trailing Edge ◽  
Control Effort ◽  
Rotor Systems ◽  
Aeroelastic Analysis ◽  
Strip Theory ◽  
Trailing Edge Flaps ◽  
Active Flap

An aeroelastic analysis of bearingless rotor systems with trailing edge flaps was conducted using large deflection-type beam theory for forward flight conditions with a focus on reducing vibration while minimizing control effort. The aerodynamic forces of the rotor blade were calculated using two-dimensional quasi-steady strip theory. For the analysis of forward flight, the nonlinear periodic blade steady response was obtained by integrating the full finite element equation in time through a coupled trim procedure with a vehicle trim. The objective function, which includes vibratory hub loads and active flap control inputs, was minimized by an optimal control process. Numerical simulations were performed for the steady-state forward flight of various advance ratios. Numerical results of the steady blade and flap deflections as well as the vibratory hub loads were also presented for various advance ratios and were compared with previously published analysis results obtained from modal analyses based on a moderate deflection-type beam theory.

Numerical Simulation and Investigation of Transonic & Symmetrical Airfoil for Helicopter Main Rotor Blade Application

2014 ◽  
Vol 704 ◽  
pp. 137-142
Author(s):  
Ziad bin Abdul Awal ◽  
Mohd Shariff bin Ammoo
Keyword(s):  
Rotor Blade ◽  
Lift Coefficient ◽  
Computational Simulation ◽  
Main Rotor ◽  
Rotor Aerodynamics ◽  
Stability And Control ◽  
Helicopter Main Rotor ◽  
And Control ◽  
Transonic Airfoil ◽  
Main Rotor Blade

Helicopter rotor aerodynamics is prognosticated to be one of the most perplexing and enigmatic affliction encountered by both researchers and aviators throughout the ages. The bewilderment of the flow field around the main rotor blade ceaselessly remains unrequited in tangible flight environments. Appalling calamities repeatedly befall owing to these unforeseen and equivocal instances. In order to extricate these impediments, one must go back to the brass tacks and apprehend the cause. However, it is every so often exceedingly disconcerting to obtain experimental data due to intricacy, perplexity and substantial price tag. Subsequently, computational simulation is progressively becoming more of a preferred choice in recent times. Bearing this in mind, this study intended to simulate and visualize the air flow configuration of the main rotor blade using symmetrical and transonic airfoils to demarcate their physiognomies and behavior. Results have revealed that the transonic airfoil has a higher lift coefficient (Cl) than the symmetrical airfoil. Contrariwise, if used in an actual rotorcraft, the transonic airfoil can cause stern apprehension in terms of stability and control.

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