Active Load Control of an Articulated Composite Rotor Blade via Dual Trailing Edge Flaps

2003 ◽  
Author(s):  
Jun-Sik Kim ◽  
Edward Smith ◽  
Kon-Well Wang
Keyword(s):  
Rotor Blade ◽  
Load Control ◽  
Trailing Edge ◽  
Active Load ◽  
Trailing Edge Flaps

scholarly journals Pressure Based Lift Estimation and its Application to Feedforward Load Control employing Trailing Edge Flaps

2020 ◽  
Author(s):  
Sirko Bartholomay ◽  
Tom T. B. Wester ◽  
Sebastian Perez-Becker ◽  
Simon Konze ◽  
Christian Menzel ◽  
...  
Keyword(s):  
Surface Pressure ◽  
Feedforward Control ◽  
Force Balance ◽  
Estimation Methods ◽  
Load Control ◽  
Trailing Edge ◽  
Trailing Edge Flaps ◽  
Feedforward Controller ◽  
Trailing Edge Flap ◽  
C 30

Abstract. This experimental load control study presents results of an active trailing edge flap feedforward controller for wind turbine applications. The controller input is derived from pressure based lift estimation methods that rely either on a quasi-steady method, based on a three-hole probe, or on an unsteady method that is based on three selected surface pressure ports. Furthermore, a standard feedback controller, based on force balance measurements, is compared to the feedforward control. A Clark-Y airfoil is employed for the wing that is equipped with a trailing edge flap of x/c = 30 % chordwise extension. Inflow disturbances are created by a two-dimensional active grid. The Reynolds number is Re = 290,000 and reduced frequencies of k = 0.07 up to k = 0.32 are analyzed. Within the first part of the paper, the lift estimation methods are compared. The surface pressure based method shows generally more accurate results whereas the three-hole probe estimate overpredicts the lift amplitudes with increasing frequencies. Nonetheless, employing the latter as input to the feedforward controller is more promising as a beneficial phase lead is introduced by this method. A successful load alleviation was achieved up to reduced frequencies of k = 0.192.

scholarly journals Active Aerodynamic Load Control of Wind Turbine Blades

2007 ◽  
Author(s):  
Dale E. Berg ◽  
Jose R. Zayas ◽  
Donald W. Lobitz ◽  
C. P. van Dam ◽  
Raymond Chow ◽  
...  
Keyword(s):  
Turbine Blades ◽  
Cost Effective ◽  
Rotor Blades ◽  
Load Control ◽  
Aerodynamic Load ◽  
Wind Turbine Blades ◽  
Trailing Edge ◽  
Trailing Edge Flaps ◽  
Control Devices ◽  
The Cost

The cost of wind-generated electricity can be reduced by mitigating fatigue loads acting on the rotor blades of wind turbines. One way to accomplish this is with active aerodynamic load control devices that supplement the load control obtainable with current full-span pitch control. Thin airfoil theory suggests that such devices will be more effective if they are located near the blade trailing edge. While considerable effort in Europe is concentrating on the capability of conventional trailing edge flaps to control these loads, our effort is concentrating on very small devices, called microtabs, that produce similar effects. This paper discusses the work we have done on microtabs, including a recent simulation that illustrates the large impact these small devices can exert on a blade. Although microtabs show promise for this application, significant challenges must be overcome before they can be demonstrated to be a viable, cost-effective technology.

Active load control for wind turbine blades using trailing edge flap

2013 ◽  
Vol 16 (3) ◽  
pp. 263-278 ◽  
Author(s):  
Jong-Won Lee ◽  
Joong-Kwan Kim ◽  
Jae-Hung Han ◽  
Hyung-Kee Shin
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Load Control ◽  
Wind Turbine Blades ◽  
Trailing Edge ◽  
Active Load ◽  
Trailing Edge Flap

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.

Active load reduction by means of trailing edge flaps on a wind turbine blade

2014 ◽  
Author(s):  
Ian Couchman ◽  
Damien Castaignet ◽  
Niels K. Poulsen ◽  
Thomas Buhl ◽  
Jens Jakob Wedel-Heinen ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Wind Turbine Blade ◽  
Load Reduction ◽  
Trailing Edge ◽  
Active Load ◽  
Trailing Edge Flaps

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.

Dynamic Aeroelastic Response of Wind Turbine Rotors Under Active Flow Control

2019 ◽  
Author(s):  
Muraleekrishnan Menon ◽  
Fernando L. Ponta
Keyword(s):  
Flow Control ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Active Flow Control ◽  
Load Control ◽  
Aerodynamic Load ◽  
Trailing Edge ◽  
Trailing Edge Flaps ◽  
Utility Scale ◽  
Active Flow

Abstract The significance of wind power and the associated relevance of utility-scale wind turbines are becoming more prominent in tapping renewable sources for power. Operational wind turbines today rated at 8 MW have rotor diameters of 164 m. Economies-of-scale factor suggest a sustained growth in rotor size, forecasting the use of longer and heavier blades. This has led to an increased emphasis on studies related to improvements and innovations in aerodynamic load-control methodologies. Among several approaches to controlling the stochastic aerodynamics loads on wind turbine rotors, most popular is the pitch control. Widely used in operational wind turbines, conventional pitch control is an effective approach for long-term load variations. However, their application to mitigate short-term fluctuations have limitations that present a bottleneck for growth in rotor size. Sporadic changes occurring within short time scales near the turbine rotor have significant impact on the aeroelastic behavior of the blades, power generation, with long-term effects on the rotor life-span. Cyclic variations occurring within few seconds emphasize the need for swift response of control methods that counter the resulting adverse effects. Current study revolves around the need to evaluate innovative active load control techniques that can swiftly handle high frequency oscillations in dynamic loading of turbine rotors. This may result from sudden changes in wind conditions due to gusts, environmental effects like atmospheric boundary layer and uneven terrain, or from turbine design features and operating conditions such as tower shadow effects. The upward surge in rotor size is linked with a down-side for existing techniques in rotor control that now need to account for heavier blades and the associated inertia. For example, the pitching operation rotates the entire blade around its longitudinal axis to regulate angle of wind at specific blade sections, involving huge inertial loads associated with the entire blade. On the other hand, active flow-control devices (FCDs) have the potential to alleviate load variations through rapid aerodynamic trimming. Trailing-edge flaps are light weight attachments on blades that have gradually gained relevance in studies focused on wind turbine aerodynamics and active load control. This computational study presents an aeroelastic assessment of a benchmark wind turbine based on the NREL 5-MW Reference Wind Turbine (RWT), with added trailing-edge flaps for rapid load control. The standard blades used on the NREL 5-MW RWT rotor are aerodynamically modified to equip them with actively controllable fractional-chord trailing-edge flaps, along a selected span. The numerical code used in the study handles the complex multi-physics dynamics of a wind turbine based on a self-adaptive ODE algorithm that integrates the dynamics of the control system in to the coupled response of aerodynamics and structural deformations of the rotor. Using the 5-MW RWT as a reference, the blades are modified to add trailing-edge flaps with Clark Y profile and constant chord. Attached at chosen sections of the blade, these devices have a specific range of operational actuation angles. Numerical experiments cover scenarios relevant to the aeroelastic response of a rotor with such adapted blades under operating conditions observed in utility-scale wind turbines. These fractional-chord devices attached along short spans of the blades make them light weight devices that can be easily controlled using low power of actuation. This overcomes the bottleneck in active aerodynamic load control, giving flexibility to study a wider ranged of control strategies for utility-scale wind turbines of the future. Preliminary outcomes suggest that rapid active flow control has high potential in shaping the future of aerodynamic load control in wind turbines.

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