
Gijs van Kuikretired from Delft University of Technology
Gijs van Kuik
emeritus professor
About
122
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Introduction
Publications
Publications (122)
Usually, the load on lifting bodies in incompressible, inviscid flow is determined by integration of the pressure on the body surface, once the flow is solved. Prandtl ( Nachrichten von der Gesellschaft der Wissenschaften zu Göttingen, Mathematisch- Physikalische Klasse , vol. 1918, pp. 451–477) proposed an opposite method in which the body force f...
The first version of the actuator disc momentum theory is more than 100 years old. The extension towards very low rotational speeds with high torque for discs with a constant circulation became available only recently. This theory gives the performance data like the power coefficient and average velocity at the disc. Potential flow calculations hav...
Abstract. The first version of the actuator disc momentum theory is more than 100 years old. The extension towards very low rotational speeds with high torque for discs with a constant circulation, became available only recently. This theory gives the performance data like the power coefficient and average velocity at the disc. Potential flow calcu...
Two new engineering models are presented for the aerodynamic induction of a wind turbine under dynamic thrust. The models are developed using the differential form of Duhamel integrals of indicial responses of actuator disc type vortex models. The time constants of the indicial functions are obtained by the indicial responses of a linear and a nonl...
The currently most used theory for rotor aerodynamics — Blade Element Momentum is based on the assumption of stationary wake conditions. However, an unsteady rotor loading results in an unsteady wake flow field. This work aims to study the impact of an unsteady actuator disc on the wake flow field using a free wake vortex ring model. The numerical...
Actuator disc theory is the basis for rotor design and analysis, valid for discs representing wind turbine rotors as well as propellers. In Froude's momentum theory swirl is absent, in Joukowsky's momentum theory this is included. The momentum theory including swirl, developed in WES, 2:307-316,2017, as well as potential flow calculations have been...
The first rotor performance predictions were published by Joukowsky exactly 100 years ago. Although a century of research has expanded the knowledge of rotor aerodynamics enormously, and modern computer power and measurement techniques now enable detailed analyses that were previously out of reach, the concepts proposed by Froude, Betz, Joukowsky a...
The Blade Element Momentum model, which is based on the actuator disc theory, is still the model most used for the design of open rotors. Although derived from steady cases with a fully developed wake, this approach is also applied to unsteady cases, with additional engineering corrections. This work aims to study the impact of an unsteady loading...
Actuator disc theory is the basis for most rotor design methods, albeit with many extensions and engineering rules added to make it a well-established method. However, the off-design condition of a very low rotational speed Ω of the disc is still a topic for scientific discussions. Several authors have presented solutions of the associated momentum...
The presence of conservative forces on rotor blades is neglected in the blade element theory and all the numerical methods derived from it (like e.g. the blade element momentum theory and the actuator line technique). This might seem a reasonable simplification of the real flow of rotor blades, since conservative loads, by definition, do not contri...
Actuator disc theory is the basis for most rotor design methods, be it with many extensions and engineering rules added to make it a well-established method. However, the off-design condition of a very low rotational speed Ω of the disc is still a topic for scientific discussions. Several authors have presented solutions of the associated momentum...
Wind turbine load alleviation has traditionally been addressed in the literature using either full-span pitch control, which has
limited bandwidth, or trailing-edge flap control, which typically shows low
control authority due to actuation constraints. This paper combines both
methods and demonstrates the feasibility and advantages of such a combin...
Actuator disc theory is the basis for most rotor design methods, be it with many extensions and engineering rules added to make it a well-established method. However, the off-design condition of a very low rotational speed Ω of the disc is still a topic for scientific discussions. Several authors have presented solutions of the associated momentum...
Trailing edge flaps located outboard on wind turbine blades have recently shown considerable potential in the alleviation of turbine lifetime dynamic loads. The concept of the free-floating flap is specifically interesting for wind turbines, on account of its modularity and enhanced control authority. Such a flap is free to rotate about its axis; c...
The state of the art engineering dynamic inflow models of Pitt-Peters, Øye and ECN have been used to correct Blade Element Momentum theory for unsteady load prediction of a wind turbine for two decades. However, their accuracy is unknown. This paper is to benchmark the performance of these engineering models by experimental and numerical methods. T...
In this paper we report the results of a workshop organised by the Delft University of Technology in 2014, aiming at the comparison between different state-of-the-art numerical models for the simulation of wind turbine wakes. The chosen benchmark case is a wind tunnel measurement, where stereoscopic Particle Image Velocimetry was employed to obtain...
In this paper the reductions of fatigue and extreme loads of wind turbine components are analysed. An individual flap controller was designed to reduce cyclic loads. The load reduction potential was computed for power production and start-up load cases with normal and extreme turbulence, extreme gust events, and direction changes according to the c...
Although the Blade Element Momentum method has been derived for the steady conditions, it is used for unsteady conditions by using corrections of engineering dynamic inflow models. Its applicability in these cases is not yet fully verified. In this paper, the validity of the assumptions of quasi-steady state and annuli independence of the blade ele...
Wind turbine load alleviation has traditionally been addressed in literature using either full-span pitch control, which has limited bandwidth, or trailing-edge flap control, which typically shows low control authority due to actuation constraints. This paper combines both methods, and demonstrates the feasibility and advantages of such a combined...
Wind turbine upscaling is motivated by the fact that larger machines can achieve lower levelized cost of energy. However, there are several fundamental issues with the design of such turbines, and there is little public data available for large wind turbine studies. To address this need, we develop a 20 MW common research wind turbine design that i...
The European Academy of Wind Energy (eawe), representing universities and institutes with a significant wind energy programme in 14 countries, has discussed the long-term research challenges in wind energy. In contrast to research agendas addressing short- to medium-term research activities, this eawe document takes a longer-term perspective, addre...
This book presents the view of European wind energy experts on the long-term research challenges to be solved in order to develop wind energy beyond the applications of today and tomorrow. By this book, the European Academy of Wind Energy (eawe), representing universities and institutes with a significant wind energy programme in 14 countries, want...
The actuator disc is the oldest representation of a rotor, screw or propeller. Performance prediction is possible by applying momentum theory, giving integrated values for power and velocity. Computational fluid dynamics has provided much more flow details, but a full potential flow solution zooming in on these flow details was still absent. With t...
The structural cost of offshore wind energy can be drastically reduced by the development of floating wind turbines. However, the design of a feedback controller for rotor speed control of such turbines faces fundamental bandwidth limitations because of the presence of nonminimum phase zeros. New developments in lidar technology enable turbines to...
In van Kuik & Lignarolo (2015, Wind Energy accepted with modifications) potential flow solutions have been obtained for classical actuator discs (axisymmetric, uniform load) presenting a model for the non-uniformity of the axial velocity at the disc. Current rotor design models proceed from a disc with a uniform axial velocity, modified by a tip co...
This paper is the first of two papers on the history of rotor aerodynamics with special emphasis on the role of Joukowsky. The present one focuses on the development of the momentum theory while the second one surveys the development of vortex theory for rotors. Joukowsky has played a major role in these developments. Although he cooperated with ot...
In this paper one of the �rst utility scale smart rotors is studied in detail. The structural response of the Sandia National Laboratories Smart Rotor Experiment due to flap excitation has been modeled by the in-house code DU-SWAT and compared to experimental data. Good agreement has been found for both tower and blade motion. The numerically obtai...
Most state of the art rotor design methods are based on the actuator disc theory developed about one century ago. The actuator disc is an axisymmetric permeable surface carrying a load that represents the load on a real rotor with a finite number of blades N. However, the mathematics of the transition from a real rotor load to an axisymmetrically l...
During the last decade research on the field of smart rotor has advanced significantly. Fundamental aerodynamics, structural and control concepts have been established and simulators created for distributed flaps on wind turbine blades, which are considered the most promising option. Also a proof of concept has been done under laboratory conditions...
In most rotor design methods, the blade load is found by a blade element analysis in an iterative procedure with flow solvers like actuator disc and -line analyses as well as momentum balances. For the flow solvers the force field is the input. In most other aerodynamic analyses the force field is the output result instead of input. This is done by...
This paper presents a method for multidisciplinary design optimization of offshore wind turbines at system level. The formulation and implementation that enable the integrated aerodynamic and structural design of the rotor and tower simultaneously are detailed. The objective function to be minimized is the levelized cost of energy. The model includ...
This paper presents a method for multidisciplinary design optimization of offshore wind turbines at system level. The formulation and implementation that enable the integrated aerodynamic and structural design of the rotor and tower simultaneously are detailed. The objective function to be minimized is the levelized cost of energy. The model includ...
The theory to predict the performance and loads on rotors (propellers, screws, windmills) has a history of more than a century. Apart from modern computational fluid dynamics and vortex panel models taking the true blade geometry into account, most other models proceed from an infinitely thin actuator disc or line. These models assume an externally...
Individual pitch control (IPC) for reducing blade loads has been investigated and proven successful in recent literature. For IPC, the multi-blade co-ordinate (MBC) transformation is used to process the blade load signals from the rotating to a stationary frame of reference. In the stationary frame of reference, the yaw error of a turbine can be ap...
In the past year, smart rotor technology has been studied significantly as solution to the ever growing turbines. Aeroservoelastic tools are used to asses and predict the behavior of rotors using trailing edge devices like flaps. In this paper an unsteady aerodynamic model (Beddoes-Leishman type) and an CFD model (URANS) are used to analyze the aer...
A novel Subspace Predictive Repetitive Control (SPRC) methodology is presented and used to control trailing edge flaps for wind turbines. First, the dynamics of the wind turbine are identified online. This is especially important for trailing edge flaps on a large wind turbine, where a local change in wind conditions can result in significantly alt...
Manufacturing and maintenance costs arising out of wind turbine dynamic loading are one of the largest bottlenecks in the roll-out of wind energy. Individual Pitch Control (IPC) is being researched for cost reduction through load alleviation; it poses a challenging mechatronic problem due to its multi-input, multi-output (MIMO) nature and actuation...
The purpose of this study is the examination of optimum rotor theories with ideal load distributions along the blades, to analyze some of the underlying ideas and concepts, as well as to illuminate them. The book gives the historical background of the issue and presents the analysis of the problems arising in the actuator disc theory -the simplest...
In this paper an individual flap controller (IFC) design for smart rotors is presented and compared to the model identification of the Sandia National Labs Smart Rotor experiment. The controller design has been carried out using an in-house aeroservoelastic software - DU_SWAT. The root bending moment response due to a step input of the flap deflect...
In this article the proof of concept of a smart rotor is illustrated, by aeroelastic simulations on a small scale rotor and comparison with wind tunnel experiments. The application of advanced feedback controllers using actively deformed flaps in the wind tunnel measurements is shown to alleviate dynamic loads leading to considerable fatigue load r...
This paper describes the implementation of system identification and controller design techniques using model predictive control (MPC) for wind turbines with distributed active flaps for load control. An aeroservoelastic model of the 5?MW NREL/Upwind reference wind turbine, implemented in the code DU_SWAMP, is used in an industry-based MPC controll...
The derivation of the efficiency of an ideal wind turbine has been attributed to the three famous scientists of the three aerodynamic research schools in Europe during the first decades of the previous century: Lanchester, Betz and Joukowsky. However, detailed reading of their classical papers has shown that Lanchester did not accept Froude's resul...
General momentum theory is used to study the behaviour of the ‘classical’ free vortex wake model of Joukowsky. This model has recently attained considerable attention as it shows the possibility of achieving a power performance that greatly exceeds the Lanchester-Betz limit for rotors running at low tip speed ratios. This behaviour is confirmed eve...
This paper studies the load reduction potential of a prototyped “smart” rotor. This is, a rotor where the blades are equipped with a number of control devices that locally change the lift profile on the blade, combined with appropriate sensors and controllers. Experimental models, using dedicated system identification techniques, are developed of a...
The ever increasing size of wind turbines poses a number of design issues for the industry, like increasing component mass and fatigue loads. An interesting concept for reducing fatigue loads is the implementation of spanwise distributed devices to control the aerodynamic loading along the span of the blade, thus mitigating fluctuations in loading...
This paper focuses on evaluating the feasibility of estimating loads on vertical axis wind turbine blades in dynamic stall with velocity data acquired with Particle Image Velocimetry. The study uses numerical simulation data of a 2D Vertical Axis Wind Turbine in dynamic stall to verify sources of error and uncertainty and estimate the accuracy of t...
Reducing the loads experienced by wind turbine rotor blades can lower the cost of energy of wind turbines. "Smart rotor control" concepts have emerged as a solution to reduce fatigue loads on wind turbines. In this approach, aerodynamic load control devices are distributed along the span of the blade, and through a combination of sensing, control,...
This article presents a review of the state of the art and present status of active aeroelastic rotor control research for wind turbines. Using advanced control concepts to reduce loads on the rotor can offer great reduction to the total cost of wind turbines. With the increasing size of wind turbine blades, the need for more sophisticated load con...
Active aerodynamic load control of wind turbine blades is being investigated by the wind energy research community and shows great promise, especially for reduction of turbine fatigue damage in blades and nearby components. For much of this work, full system aeroelastic codes have been used to simulate the operation of the actively controlled rotor...
This paper develops a system identification approach and procedure that is employed for distributed control system design for large wind turbine load reduction applications. The primary goal of the study is to identify the process that can be used with multiple sensor inputs of varying types (such as aerodynamic or structural) that can be used to c...
The Vertical Axis Wind Turbine, in its 2D form, is characterized by a complex unsteady aerodynamic flow, including dynamic stall and blade vortex interaction. Adding to this complexity, the 3D flow causes spanwise effects and the presence of trailing vorticity and tip vortices. The objective of the current paper is to bring insight into the 3D deve...
The implementation of wind energy conversion systems in the built environment has renewed the interest and the research on Vertical Axis Wind Turbines (VAWTs).
The VAWT has an inherent unsteady aerodynamic behavior due to the variation of angle of attack and perceived velocity with azimuth angle. The phenomenon of dynamic stall is then an intrinsic...
The purpose of this paper is to integrate the controller design of wind turbines with structure and aerodynamic analysis and use the final product in the design optimization process (DOP) of wind turbines. To do that, the controller design is automated and integrated with an aeroelastic simulation tool. This integrated tool is linked with an optimi...
A wind turbine blade has a complex shape and consists of different elements with dissimilar material properties. To do any aeroelastic simulation, the structural properties of the blade such as stiffnesses and mass per unit length should be known in advance, and extracting these properties is a difficult task. This paper presents an analytical mode...
The aerodynamic behavior of a vertical axis wind turbine (VAWT) is analyzed by means of 2D particle image velocimetry (PIV),
focusing on the development of dynamic stall at different tip speed ratios. The VAWT has an unsteady aerodynamic behavior
due to the variation with the azimuth angle θ of the blade’s sections’ angle of attack, perceived veloc...
A newly developed comprehensive aeroelastic model is used to investigate active flap concepts on the Upwind 5MW reference wind turbine. The model is specially designed to facilitate distributed control concepts and advanced controller design. Different concepts of centralized and distributed control schemes based on choices of realistic measurement...
Prandtl's [L. Prandtl, Über die Entstehung von Wirbeln in der idealen Flüssigkeit, mit Anwendung auf die Tragflügeltheorie und andere Aufgaben, in: von Kármán, Levi-Cevita (Eds.), Vorträge aus dem Gebiete der Hydro- und Aerodynamik, Springer, Berlin, 1922] self-similar, semi-infinite, free vortex sheets are characterized by a two-dimensional unstea...
Modern wind turbines are steadily increasing in size, with recent models boasting rotor diameters greater than 120 m. Wind turbines are subjected to significant and rapid fluctuating loads, which arise from a variety of sources including turbulence, tower shadow, wind shear and yawed flow. Reducing the loads experienced by the rotor blades can lowe...
One of the results of the development of wind energy conversion solutions for the built environment is the reappearance of Vertical Axis Wind Turbines (VAWTs). The application of wind turbines in urban environments presents design challenges driven by the complex wind fields experienced in the urban boundary layer. Urban Wind Turbines operate near,...
Wind turbine design codes for calculating blade loads are usually based on a blade element momentum (BEM) approach. Since wind turbine rotors often operate in off-design conditions, such as yawed flow, several engineering methods have been developed to take into account such conditions. An essential feature of a BEM code is the coupling of local bl...
Actuator disc calculations can be divided in two categories: force models where, for a prescribed force field, the flow is calculated using a CFD method, and kinematic models, where the wake is calculated based on wake boundary conditions and the force field is known when the velocities are known. In both categories, but specifically for the kinema...
The Blade Element Momentum theory is based on the work of Glauert who formulated the equations to derive thrust, torque and power as a function of the tip speed ratio λ and axial induction. The moment of momentum applied to the wake, is taken into account in his theory with one major simplification. The radial pressure distribution required to main...
A newly developed comprehensive aeroelastic model is used to investigate active flap concepts on the Upwind 5MW reference wind turbine. The model is specially designed to facilitate distributed control concepts and advanced controller design. Different concepts of centralized and distributed control schemes based on choices of realistic measurement...
To reduce the level of uncertainty associated with current rotor aerodynamics codes, improved understanding of rotor aerodynamics is required. Wind tunnel measurements on model rotors contribute to advancing our knowledge on rotor aerodynamics. The combined recording of blade loads and rotor wake is desired, because of the coupled blade and wake ae...
An improved physical understanding of the rotor aerodynamics of a horizontal axis wind turbine (HAWT) is required to reduce the uncertainties associated with today's design codes. Wind tunnel experiments contribute to increased knowledge and enable validation and construction of models. The present study focuses on the near-wake of a model HAWT in...
The trend with offshore wind turbines is to increase the rotor diameter as much as possible to decrease the costs per kilowatt-hour. The increasing dimensions have led to the relative increase of the loads on the wind turbine structure. Because of the increasing rotor size and the spatial load variations along the blade, it is necessary to react to...
Most modern large wind turbines run at variable rotational speed with collective control of the blade pitch angle. The latter has not only led to high quality power regulation, but also to a signifi cantly lighter blade construction. The next step in blade load control is pitch angle adjustment per blade instead of collective. This will further all...
Wind tunnel tests on a non-rotating, dynamically scaled wind turbine blade equipped with variable trailing edge geometry were carried out. The effectiveness of the system for active load reduction purposes, with the interaction between structural dynamics, aerodynamics and control was tested. The actuation of the adaptive trailing edge was based on...
The increasing awareness of the need for environmentally sustainable housing and cities has driven the promotion of wind energy conversion systems for the built environment. One of the results of the development of solutions for the built environment is the reappearance of Vertical Axis Wind Turbines (VAWTs). In the built environment, the VAWT pres...
Wind energy has conquered many startup problems and has attained in a new, more mature phase. The annual market volume increases Wind energy has conquered many startup problems and has attained in a new, more mature phase. The annual market volume increases
by 20–30% per year, making significant contributions to the national electricity supply in s...