Comportement dynamique d'une éolienne à axe vertical (développement théorique)

1988 ◽  
Vol 15 (3) ◽  
pp. 355-368
Author(s):  
Mario Veilleux ◽  
René Tinawi
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Instability ◽  
Equations Of Motion ◽  
Vertical Component ◽  
Vertical Axis ◽  
Nonlinear Static Analysis ◽  
Mode Shapes ◽  
Vertical Axis Wind Turbine ◽  
Qr Algorithm ◽  
Gyroscopic Effects

Complex frequencies and mode shapes are evaluated and presented for a guyed vertical axis wind turbine to detect any dynamic instability for a given speed of rotation. The equations of motion are developed in the rotating system of axes of the rotor to eliminate the time dependent terms. These equations take into account gyroscopic effects by evaluating the Coriolis and Circulatory (softening) matrices. The guys are replaced by nonlinear springs. The geometric stiffness matrix is also considered by performing a nonlinear static analysis that includes centrifugal effects and gravity loads, as well as compression from the vertical component of the guys. A reduction of the dynamic degrees of freedom is performed using the Rayleigh–Ritz technique. The complex frequencies and mode shapes are obtained using the QR algorithm. A program developed on a microcomputer was used to evaluate the dynamic instabilities of the ÉOLE Project. These results are described in the following paper. Key words: Vertical axis wind turbines, guys, complex frequencies, complex mode shapes, centrifugal forces, Coriolis forces, numerical software.

Comportement dynamique d'une éolienne à axe vertical (application pratique)

1988 ◽  
Vol 15 (3) ◽  
pp. 369-381
Author(s):  
Mario Veilleux ◽  
René Tinawi
Keyword(s):  
Dynamic Behaviour ◽  
Vertical Axis ◽  
Mode Shapes ◽  
Nonlinear Behaviour ◽  
Vertical Axis Wind Turbine ◽  
Initial Tension ◽  
Coriolis Forces ◽  
Gravity Forces ◽  
Vertical Axis Wind Turbines ◽  
Gyroscopic Effects

The dynamic behaviour of the vertical axis wind turbine of the ÉOLE Project is examined using a special purpose program developed for extracting the complex frequencies and mode shapes of the structure. The precise evaluation of the frequencies is an important step in the design process, to detect any dynamic instabilities of the rotor for a given speed. Gyroscopic effects and geometric nonlinearities due to centrifugal and gravity forces as well as the vertical compression due to the tension of the guys are also considered. Nonlinear behaviour of the guys is also accounted for. The influence of the variation in the stiffness of the guys on the dynamic behaviour is examined specifically for the ÉOLE Project. Results indicate that this effect is not important if the initial tension in the guy is high. Key words: Vertical axis wind turbines, guys, complex frequencies, complex mode shapes, centrifugal forces, Coriolis forces, Campbell diagrams, numerical software.

Mean Wave Drift Force on a Barge-Type Floating Wind Turbine With Moonpools

2021 ◽  
Author(s):  
Lei Tan ◽  
Tomoki Ikoma ◽  
Yasuhiro Aida ◽  
Koichi Masuda
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Offshore Wind ◽  
Hydrodynamic Performance ◽  
Vertical Axis Wind Turbine ◽  
Rotating Speed ◽  
Wave Drift ◽  
Floating Offshore Wind Turbines ◽  
Drift Force ◽  
Gyroscopic Effects

Abstract The barge-type foundation with moonpool(s) is a promising type of platform for floating offshore wind turbines, since the moonpool(s) could improve the hydrodynamic performance at particular frequencies and reduce the costs of construction. In this paper, the horizontal mean drift force and yaw drift moment of a barge-type platform with four moonpools are numerically and experimentally investigated. Physical model tests are carried out in a wave tank, where a 2MW vertical-axis wind turbine is modelled in the 1:100 scale. By varying the rotating speed of the turbine and the mass of the blades, the gyroscopic effects due to turbine rotations on the mean drift forces are experimentally examined. The wave diffraction and radiation code WAMIT is used to carry out numerical analysis of wave drift force and moment. The experimental results indicate that the influence of the rotations of a vertical-axis wind turbine on the sway drift force is generally not very significant. The predictions by WAMIT are in reasonable agreement with the measured data. Numerical results demonstrate that the horizontal mean drift force and yaw drift moment at certain frequencies could be reduced by moonpool(s).

Effect of a Planetary Gearbox on the Dynamics of a Rotor System

2018 ◽  
Author(s):  
Ali Tatar ◽  
Christoph W. Schwingshackl
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Behaviour ◽  
Rotor System ◽  
Mode Shapes ◽  
Rotating System ◽  
Planetary Gearbox ◽  
Finite Element Software ◽  
Gyroscopic Effects ◽  
The Masses ◽  
Parameter Values

The dynamic analysis of rotors with bladed disks has been investigated in detail over many decades and is reasonably well understood today. In contrast, the dynamic behaviour of two rotors that are coupled via a planetary gearbox is much less well understood. The planetary gearbox adds inertia, mass, stiffness, damping and gyroscopic moments to the system and can strongly affect the modal properties and the dynamic behaviour of the global rotating system. The main objective of this paper is to create a six degrees of freedom numerical model of a rotor system with a planetary gearbox and to investigate its effect on the coupled rotor system. The analysis is based on the newly developed finite element software “GEAROT” which provides axial, torsional and lateral deflections of the two shafts at different speeds via Timoshenko beam elements and also takes gyroscopic effects into account. The disks are currently considered as rigid and the bearings are modelled with isotropic stiffness elements in the translational and rotational directions. A novel planetary gearbox model has been developed, which takes the translational and rotational stiffness and the damping of the gearbox, as well as the masses and inertias of the sun gear, ring gear, planet gears and carrier into account. A rotating system with a planetary gearbox has been investigated with GEAROT. The gearbox mass and stiffness parameters are identified as having a significant effect on the modal behaviour of the rotor system, affecting its natural frequencies and mode shapes. The higher frequency modes are found to be more sensitive to the parameter changes as well as the modes which have a higher deflection at the location of the gearbox on the rotor system. Compared with a single shaft system, the presence of a gearbox introduces new global modes to the rotor system and decouples the mode shapes of the two shafts. The introduction of a planetary gearbox may also lead to an increase or a reduction of the frequency response of the rotor system based on gear parameter values.

scholarly journals Aerodynamics and Modal Analysis for the Combined Vane type Vertical Axis Wind Turbine

2018 ◽  
Vol 7 (4.38) ◽  
pp. 1395 ◽  
Author(s):  
Kadhim H. Suffer ◽  
Yassr Y. Kahtan ◽  
Zuradzman M. Razlan
Keyword(s):  
Wind Turbine ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Turbine Rotor ◽  
Mode Shapes ◽  
Vertical Axis Wind Turbine ◽  
Ansys Fluent ◽  
Starting Torque

The present global energy economy suggests the use of renewable sources such as solar, wind, and biomass to produce the required power. The vertical axis wind turbine is one of wind power applications. Usually, when the vertical axis wind turbine blades are designed from the airfoil, the starting torque problem begins. The main objective of this research is to numerically simulate the combination of movable vanes of a flat plate with the airfoil in a single blade configuration to solve the starting torque problem. CFD analysis in ANSYS-FLUENT and structural analysis in ANSYS of combined blade vertical axis wind turbine rotor has been undertaken. The first simulation is carried out to investigations the aerodynamic characteristic of the turbine by using the finite volume method. While the second simulation is carried out with finite element method for the modal analysis to find the natural frequencies and the mode shape in order to avoid extreme vibration and turbine failure, the natural frequencies, and their corresponding mode shapes are studied and the results were presented with damping and without damping for four selected cases. The predicted results show that the static pressure drop across the blade increase in the active blade side because of the vanes are fully closed and decrease in the negative side because of the all the vanes are fully open. The combined blade helps to increase turbine rotation and so, thus, the power of the turbine increases. While the modal results show that until the 5th natural frequency the effect of damping can be neglected. The predicted results show agreement with those reported in the literature for VAWT with different blade designs.   

FloVAWT: Progress on the Development of a Coupled Model of Dynamics for Floating Offshore Vertical Axis Wind Turbines

2013 ◽  
Author(s):  
Maurizio Collu ◽  
Michael Borg ◽  
Andrew Shires ◽  
Feargal P. Brennan
Keyword(s):  
Experimental Data ◽  
Wind Turbines ◽  
Three Dimensional ◽  
Coupled Model ◽  
Vertical Axis ◽  
Potential Method ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Wind Profiles ◽  
Gyroscopic Effects

In the present article, progress on the development of an aero-hydro-servo-elastic coupled model of dynamics for floating Vertical Axis Wind Turbines (VAWTs) is presented, called FloVAWT (Floating Vertical Axis Wind Turbine). Aerodynamics is based on Paraschivoiu’s Double-Multiple Streamtube (DMST) model [1] [2], relying on blade element momentum (BEM) theory, but also taking into account three-dimensional effects, dynamic stall, and unsteady wind profiles and platform motions. Hydrodynamics is modelled with a time domain seakeeping model [3], based on hydrodynamic coefficients estimated with a frequency analysis potential method. In this first phase of the research program, the system is considered a rigid body. The mooring system is represented through a user defined force-displacement relationship. Due to the lack of experimental data on offshore floating VAWTs, the model has initially been validated by taking each module separately and comparing it against known experimental data, showing good agreement. The capabilities of the program are illustrated through a case study, giving an insight on the relative importance of aerodynamics loads and gyroscopic effects with respect to hydrodynamic load effects.

On establishing equations of motion of mechanical vibration systems placed on moving bases

2017 ◽  
Vol 45 (3) ◽  
pp. 209-227
Author(s):  
M Gürgöze ◽  
F Terzioğlu
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Mechanical Vibration ◽  
Main Idea ◽  
Vertical Axis ◽  
Constant Angular Velocity ◽  
Vibration System ◽  
Reaction Forces ◽  
The Subject ◽  
Vibrating Systems

The first author has been teaching the postgraduate course, “The Dynamics of Mechanical Systems” in The ITU Faculty of Mechanical Engineering for nearly 20 years. He has observed that students frequently have problems in obtaining the equations of motion of the vibrating systems which were placed on moving bases. Starting from this observation, he has found that the homework stated below, which was given to the students occasionally, was very helpful in learning the subject. The main idea of the homework is the derivation of the equations of motion, with the help of formulating the Lagrange’s equations with respect to a moving set of axis for a vibration system with two degrees of freedom which consists of a horizontal table rotating with a constant angular velocity around a vertical axis. The students were also asked to solve the same problem with a different method of their choice and to determine the reaction forces as well. We want to share this problem with the reader, which we have assessed as very instructive and appropriate from the viewpoint of applicability of different methods.

Dynamic Analysis of the Optimized Savonius Vertical Axis Wind Turbine Composite Blades

2021 ◽  
pp. 1-7
Author(s):  
Sobhy Ghoneam ◽  
Ahmed Hamada ◽  
Taha S. Sherif
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Dynamic Characteristics ◽  
Dynamic Performance ◽  
Vertical Axis ◽  
Mode Shapes ◽  
Speed Ratio ◽  
Damping Factor ◽  
Vertical Axis Wind Turbine ◽  
Composite Blades

Abstract This paper presents a comprehensive study of the dynamic behavior of small vertical axis wind turbines (VAWTs) based on local fabricated Savonius VAWTs, which is suitable for countries that have moderate wind speed. The merits of this design are cleanliness, silent, start-up under low wind speed, independent wind directions, adaptability and ease of manufacturing. Also, this paper presents an experimental validation study for the optimized Savonius VAWT. Four verification test configurations of the optimized VAWT composite blades are designed, simulated and fabricated of Glass – Polyester with different stacking sequence layout for each. Modified mechanical parameters are introduced to improve the scalability, reliability, and accuracy of the developed models. Based on wind energy conversion system basics, aerodynamic characteristics (tip speed ratio (λ) and coefficient of power (Cp)), dynamic characteristics (natural frequencies and mode shapes) of Savonius-rotor models are presented and simulated within SOLIDWORKS Simulation 2020 software. The dynamic characteristics such as frequency, mode shape and damping factor are extensively investigated using Fast Fourier Transformer (FFT) analyzer. The results show that the role of composite material blades in improving the dynamic performance of a wind turbine is significant.

Numerical simulations on static and dynamic response of full-scale mast structures for H-Darrieus wind turbine

2020 ◽  
pp. 0309524X2091731
Author(s):  
Fateh Ferroudji ◽  
Lakhdar Saihi ◽  
Khayra Roummani
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Dynamic Responses ◽  
Mode Shapes ◽  
Manufacturing Cost ◽  
Vertical Axis Wind Turbine ◽  
Structural Dynamic ◽  
Finite Element Software ◽  
Von Mises ◽  
Von Mises Stresses

Mast structure is one of the most important parts of a vertical-axis wind turbine which supports generator and rotor and represents one-third of the overall costs in the production of a standard wind turbine (approximately 30%). All this may cause significant economic and physical losses when it is damaged or collapsed. The purpose of this research is to investigate numerically the static strength and structural dynamic responses of 10-kW vertical-axis wind turbine masts subjected to the aerodynamic and gravity loadings (according to the IEC 61400-2:2006 and EN 1991-1-4:2005 standards) using the SolidWorks finite element software. Mast structures with four different heights (12, 14, 16, and 18 m) and three various outer diameters (0.6, 0.7, and 0.8 m), in each height configuration, were evaluated. These analyses were performed to identify the stiffness, resistance, reliability, and natural frequency stiffness requirements within the mast structures, in order to save manufacturing cost. Based on static analysis, no structural failure is predicted for all masts during wind turbine operation according to maximum von Mises stresses at the bottom of the mast and maximum total deflections on the top of the mast. In addition, the dynamic parameters of these 12 models of masts have been studied to obtain the natural frequencies and corresponding mode shapes. Finally, the recommendations to avoid resonance and design strategy for each mast model are discussed.

Case Study: Dynamic Analysis of a Novel Vertical Axis Wind Turbine

2015 ◽  
Author(s):  
Jeffrey A. Bennett ◽  
Shane Coogan ◽  
Kenneth B. Lane
Keyword(s):  
Wind Turbine ◽  
Analytical Model ◽  
Degrees Of Freedom ◽  
Vertical Axis ◽  
Energy System ◽  
Vertical Axis Wind Turbine ◽  
Low Level ◽  
Unique System ◽  
Novel Concept

An analytical model was developed for the dynamic evaluation of a novel vertical axis wind energy system. This study was conducted early on in the design process, so the goal was to create a low level tool to determine if the concept was feasible, to perform initial sizing of the turbine, to better understand the behavior of the unique furling mechanisms, and to predict the performance. In order to prevent damage at high rotational speeds, the novel concept integrates passive mechanisms into a drag driven vertical axis wind turbine with the intention that blades furl out of the wind once a critical wind speed is reached, and passively reopen. Established wind turbine aeroelastic codes were unable to represent this unique system, therefore, a standalone analytical model was developed in Python. A Lagrangian approach was taken to represent the interactions of the system’s degrees of freedom. To complete the model, mathematical representations of the furling mechanisms and interaction of the wind on the blades was developed. Basic structural calculations were also included to determine the initial size of the primary mechanical components. This case study focuses on the development of the low-level dynamic model and shares several results of the expected behavior.

Vibration Analysis of Vertical-Axis Wind-Turbine Blades

2016 ◽  
Author(s):  
Fatemeh Afzali ◽  
Onur Kapucu ◽  
Brian F. Feeny
Keyword(s):  
Equations Of Motion ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Wind Turbine Blades ◽  
Aerodynamic Model ◽  
Vibration Model ◽  
Nonlinear Equations Of Motion ◽  
Energy Equations ◽  
Twisting Deformation

In this work the derivation of a vibration model for an H-rotor/Giromill blade is investigated. The blade is treated as a uniform straight elastic Euler-Bernoulli beam under transverse bending and twisting deformation. The derivation of the energy equations for the bending and twisting blade and a simplified aerodynamic model is issued. Lagrange’s equations are applied to assumed modal coordinates to obtain nonlinear equations of motion for bend and twist. A single quasi-steady airfoil theory is applied to obtain the aeroelastic loads. The behavior of the linearized equation for bend only is examined.

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