Gust alleviation using rapidly deployed trailing-edge flaps

Frederick, Michael A.; Kerrigan, Eric C.; Graham, John M.

doi:10.1016/j.jweia.2010.06.005

Cited by 28 publications

(17 citation statements)

References 11 publications

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“…Similarities can be observed between the microtab model proposed in this paper and the dynamic model developed by Frederick et al [18] for the actuation of small trailing-edge flaps. However, the microflap model is based on the assumptions of small angle of attack and thin aerofoil, leading to a globally linear model.…”

supporting

confidence: 82%

Microtab dynamic modelling for wind turbine blade load rejection

2014

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A dynamic model characterising the effect of microtab deployment on the aerodynamics of its base aerofoil is presented. The developed model predicts the transient aerodynamic coefficients consistent with the experimental and computational data reported in the literature. The proposed model is then used to carry out investigation on the effectiveness of microtabs in load alleviation and lifespan increase of wind turbine blades. Simulating a bang-bang controller, different load rejection scenarios are examined and their effect on blade lifespan is investigated. Results indicate that the range of frequencies targeted for rejection can significantly impact the blade fatigue life. Case studies are carried out to compare the predicted load alleviation amount and the blade lifespan using the developed model with those obtained by other researchers using the steady state model. It is shown that the assumption of an instantaneous aerodynamic response as used in the steady state model can lead to inaccurate results.

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confidence: 82%

Microtab dynamic modelling for wind turbine blade load rejection

2014

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“…Previous studies [4,5,7,[13][14][15] have shown that microtab and gurney flap have similar behaviours and, for efficiency, that microtab should have a typical height of the order of the boundary-layer thickness of the aerofoil. More precise experiments and simulations, in particular for the S809 and DU-96-W-180 aerofoils demonstrated that microtab height above 2% of the chord length results in a significant increase in drag.…”

Section: Microtab Aerodynamic Response Modellingmentioning

confidence: 99%

Integrated aeroelastic and control analysis of wind turbine blades equipped with microtabs

Macquart

Maheri

2015

Renewable Energy

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Northumbria University has developed Northumbria Research Link (NRL) to enable users to access the University's research output. Copyright © and moral rights for items on NRL are retained by the individual author(s) and/or other copyright owners. Single copies of full items can be reproduced, displayed or performed, and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided the authors, title and full bibliographic details are given, as well as a hyperlink and/or URL to the original metadata page. The content must not be changed in any way. Full items must not be sold commercially in any format or medium without formal permission of the copyright holder. The full policy is available online: http://nrl.northumbria.ac.uk/policies.html This document may differ from the final, published version of the research and has been made available online in accordance with publisher policies. To read and/or cite from the published version of the research, please visit the publisher's website (a subscription may be required.)Published in Renewable Energy 75 (2015) 102-114 Terence Macquart & Alireza Maheri 1 Integrated Aeroelastic and Control Analysis of Wind Turbine Blades Equipped with MicrotabsTerence Macquart and Alireza Maheri Faculty of Engineering and Environment, Northumbria University, UK AbstractThis paper presents the results of an investigation into the performance of different controllers in active load control of wind turbine blades equipped with microtabs. A bang-bang (BB) controller, a linear quadratic regulator (LQR) a proportional integral derivative (PID) and a sliding mode controller (SMC) are synthesised for load alleviation. The performance of the synthesised controllers in load alleviation is evaluated by employing WTAC (Wind Turbine Aeroelastic and Control), a wind turbine simulator incorporating an unsteady aerodynamic module, a structural analysis module and a control module. The variable-speed pitch-controlled NREL-5MW is adopted as the case study. Using frequency domain analysis it is shown that for the studied case all controllers have more or less the same performance at rejecting the first rotational frequency loads. It is also shown that all controllers are more effective at rejecting loads with lower frequencies. BB and PID controllers, although capable of rejecting low frequency loads, may cause amplification of loads with higher frequencies. Investigating the performance of four controllers at different wind speeds for the studied wind turbine, it is observed that the effectiveness of BB and PID controllers reduces with wind speed but on the other hand SMC and LQR perform better at higher wind speeds. Introducing a new parameter, life index, the performance of different controllers in terms of the actuation wear is investigated. It is shown that LQR cause less actuation wear compared to SMC, while having comparable performance in load alleviation.

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“…Examples include the lowering of fuel costs and greenhouse gas emissions via the drag reduction of aircraft (Bushnell 2003) and shipping (Corbett & Koehler 2003), optimal mixing of chemical reagents (Couchman & Kerrigan 2010) and wind turbine gust alleviation (Frederick et al 2010), with many more examples stemming from the natural world (Fish & Lauder 2006). Attempts to control fluid flow are typically classified into three broad categories (Gad-el-Hak 2000): passive (e.g.…”

Section: Introductionmentioning

confidence: 99%

Modelling for robust feedback control of fluid flows

et al. 2015

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This paper addresses the problem of designing low-order and linear robust feedback controllers that provide a priori guarantees with respect to stability and performance when applied to a fluid flow. This is challenging since whilst many flows are governed by a set of nonlinear, partial differential-algebraic equations (the Navier-Stokes equations), the majority of established control system design assumes models of much greater simplicity, in that they are firstly: linear, secondly: described by ordinary differential equations, and thirdly: finite-dimensional. With this in mind, we present a set of techniques that enables the disparity between such models and the underlying flow system to be quantified in a fashion that informs the subsequent design of feedback flow controllers, specifically those based on the H ∞ loop-shaping approach. Highlights include the application of a model refinement technique as a means of obtaining low-order models with an associated bound that quantifies the closed-loop degradation incurred by using such finite-dimensional approximations of the underlying flow. In addition, we demonstrate how the influence of the nonlinearity of the flow can be attenuated by a linear feedback controller that employs high loop gain over a select frequency range, and offer an explanation for this in terms of Landahl's theory of sheared turbulence. To illustrate the application of these techniques, a H ∞ loop-shaping controller is designed and applied to the problem of reducing perturbation wall-shear stress in plane channel flow. DNS results demonstrate robust attenuation of the perturbation shear-stresses across a wide range of Reynolds numbers with a single, linear controller.

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Gust alleviation using rapidly deployed trailing-edge flaps

Cited by 28 publications

References 11 publications

Microtab dynamic modelling for wind turbine blade load rejection

Microtab dynamic modelling for wind turbine blade load rejection

Integrated aeroelastic and control analysis of wind turbine blades equipped with microtabs

Modelling for robust feedback control of fluid flows

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