Prestressed Modal Analysis of the Wind Turbine Rotor Based on ANSYS Workbench

2013 ◽  
Vol 327 ◽  
pp. 301-305 ◽  
Author(s):  
Zhi Qiang Xu
Keyword(s):  
Wind Turbine ◽  
High Speed ◽  
Geometric Model ◽  
Turbine Blades ◽  
Great Influence ◽  
Turbine Rotor ◽  
Algorithm Selection ◽  
Finite Element Software ◽  
Dynamic Stiffening ◽  
Stiffening Effect

The high speed rotating prestress makes wind turbine blades produce the dynamic stiffening effect, which has great influence on the strength of the blade and the resonance frequency. The geometric model of the rotor is established in the 3D drawing software. Based on the finite element software, the meshing, the algorithm selection and material properties are discussed respectively. The modal simulation results of the prestressed condition and no prestress state are compared. The dynamic stiffening effect increases the blade original natural frequency.

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.   

scholarly journals Damage tolerance and structural monitoring for wind turbine blades

2015 ◽  
Vol 373 (2035) ◽  
pp. 20140077 ◽  
Author(s):  
M. McGugan ◽  
G. Pereira ◽  
B. F. Sørensen ◽  
H. Toftegaard ◽  
K. Branner
Keyword(s):  
Wind Turbine ◽  
Damage Tolerance ◽  
Turbine Blades ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Offshore Wind ◽  
Tolerance Index ◽  
Wind Turbine Blades ◽  
Efficient Operation ◽  
Reliable Design

The paper proposes a methodology for reliable design and maintenance of wind turbine rotor blades using a condition monitoring approach and a damage tolerance index coupling the material and structure. By improving the understanding of material properties that control damage propagation it will be possible to combine damage tolerant structural design, monitoring systems, inspection techniques and modelling to manage the life cycle of the structures. This will allow an efficient operation of the wind turbine in terms of load alleviation, limited maintenance and repair leading to a more effective exploitation of offshore wind.

Vibrations of a Three-Bladed Wind Turbine Rotor Due to Classical Flutter

2002 ◽  
Author(s):  
M. H. Hansen
Keyword(s):  
Wind Turbine ◽  
Critical Frequency ◽  
Turbine Blades ◽  
Turbine Rotor ◽  
Normal Operation ◽  
Aerodynamic Damping ◽  
Operation Conditions ◽  
Torsional Frequency ◽  
Classical Flutter ◽  
Wind Turbine Rotor

The aeroelastic stability of a three-bladed wind turbine is considered with respect to classical flutter. Previous studies have shown that the risk of stall-induced vibrations of turbine blades is related to the dynamics of the complete turbine, for example does the aerodynamic damping of a rotor whirling mode depend highly on the tower stiffness. The results of this paper indicate that the turbine dynamics also affect the risk of flutter. The study is based on an eigenvalue analysis of a linear aeroelastic turbine model. In an example of a MW sized turbine, the critical frequency of the first torsional blade mode is determined for which flutter can occur under normal operation conditions. It is shown that this critical torsional frequency is higher when the blades are interacting through the hub with the remaining turbine, than when all blades are rigidly clamped at the root. Thus, the dynamics of the turbine has increased the risk of flutter.

Design and Evaluation of a Rooftop Wind Turbine Rotor With Untwisted Blades

2013 ◽  
Author(s):  
Sayem Zafar ◽  
Mohamed Gadalla
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Low Cost ◽  
Turbine Blades ◽  
Angle Of Attack ◽  
Turbine Rotor ◽  
Wind Turbine Blades ◽  
Wind Speeds ◽  
Small Wind Turbines ◽  
Wind Turbine Rotor

A small horizontal axis wind turbine rotor was designed and tested with aerodynamically efficient, economical and easy to manufacture blades. Basic blade aerodynamic analysis was conducted using commercially available software. The blade span was constrained such that the complete wind turbine can be rooftop mountable with the envisioned wind turbine height of around 8 m. The blade was designed without any taper or twist to comply with the low cost and ease of manufacturing requirements. The aerodynamic analysis suggested laminar flow airfoils to be the most efficient airfoils for such use. Using NACA 63-418 airfoil, a rectangular blade geometry was selected with chord length of 0.27[m] and span of 1.52[m]. Glass reinforced plastic was used as the blade material for low cost and favorable strength to weight ratio with a skin thickness of 1[mm]. Because of the resultant velocity changes with respect to the blade span, while the blade is rotating, an optimal installed angle of attack was to be determined. The installed angle of attack was required to produce the highest possible rotation under usual wind speeds while start at relatively low speed. Tests were conducted at multiple wind speeds with blades mounted on free rotating shaft. The turbine was tested for three different installed angles and rotational speeds were recorded. The result showed increase in rotational speed with the increase in blade angle away from the free-stream velocity direction while the start-up speeds were found to be within close range of each other. At the optimal angle was found to be 22° from the plane of rotation. The results seem very promising for a low cost small wind turbine with no twist and taper in the blade. The tests established that non-twisted wind turbine blades, when used for rooftop small wind turbines, can generate useable electrical power for domestic consumption. It also established that, for small wind turbines, non-twisted, non-tapered blades provide an economical yet productive alternative to the existing complex wind turbine blades.

scholarly journals Enhancement of Free Vortex Filament Method for Aerodynamic Loads on Rotor Blades

2014 ◽  
Author(s):  
Hamidreza Abedi ◽  
Lars Davidson ◽  
Spyros Voutsinas
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Boundary Layer Separation ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Free Vortex ◽  
Irrotational Flow ◽  
Aerodynamic Loads ◽  
Operational Conditions ◽  
Turbine Rotor Blade

The aerodynamics of a wind turbine is governed by the flow around the rotor, where the prediction of air loads on rotor blades in different operational conditions and its relation to rotor structural dynamics is one of the most important challenges in wind turbine rotor blade design. Because of the unsteady flow field around wind turbine blades, prediction of aerodynamic loads with high level of accuracy is difficult and increases the uncertainty of load calculations. A free vortex wake method, based on the potential, inviscid and irrotational flow, is developed to study the aerodynamic loads. Since it is based on the potential, inviscid and irrotational flow, it cannot be used to predict viscous phenomena such as drag and boundary layer separation. Therefore it must be coupled to the tabulated airfoil data to take the viscosity effects into account. The results are compared with the Blade Element Momentum (BEM) [1] method and the GENUVP code [2] (see also the acknowledgments).

Design and Research on a Automatic Cleaning Device of Wind Turbine Blades

2013 ◽  
Vol 448-453 ◽  
pp. 3472-3475
Author(s):  
Tai Lv ◽  
Qiang Wang
Keyword(s):  
Wind Turbine ◽  
High Speed ◽  
Pressure Field ◽  
Turbine Blades ◽  
Positive Pressure ◽  
Wind Turbine Blades ◽  
Cleaning Device ◽  
Horizontal Axis Wind Turbines ◽  
Ash Deposit ◽  
Fluent Software

Aiming at ash deposit problem of wind turbine blades, a cleaning device for 10kW horizontal axis wind turbines was designed by applying the mechanism that ash deposit on blades surface was purged by high-speed flows from nozzle. Using fluent software, a numerical simulation was carried out in cleaning device, and its pressure field and velocity field in different cross section of wind turbine blades were simulated under cleaning state. The results showed that positive pressure zone created by cleaning device was formed on blades surface, and high-speed airflow purging blades surface was formed. As a result, the purpose of cleaning is achieved.

scholarly journals Flutter Behavior of Highly Flexible Two- and Three-bladed Wind Turbine Rotors

2021 ◽  
Author(s):  
Mayank Chetan ◽  
Shulong Yao ◽  
D. Todd Griffith
Keyword(s):  
Wind Turbine ◽  
Structural Design ◽  
Comprehensive Evaluation ◽  
Turbine Blades ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Flutter Speed ◽  
Cost Of Energy ◽  
Manufacturing Technologies

Abstract. With the progression of novel design, material, and manufacturing technologies, the wind energy industry has successfully produced larger and larger wind turbine rotor blades while driving down the Levelized Cost of Energy (LCOE). Though the benefits of larger turbine blades are appealing, larger blades are prone to aero-elastic instabilities due to their long, slender, highly flexible nature, and this effect is accentuated as rotors further grow in size. In addition to the trend of larger rotors, new rotor concepts are emerging including two-bladed rotors and downwind configurations. In this work, we introduce a comprehensive evaluation of flutter behavior including classical flutter, edgewise vibration, and flutter mode characteristics for two-bladed, downwind rotors. Flutter speed trends and characteristics for a series of both two- and three-bladed rotors are analyzed and compared in order to illustrate the flutter behavior of two-bladed rotors relative to more well-known flutter characteristics of three-bladed rotors. In addition, we examine the important problem of blade design to mitigate flutter and present a solution to mitigate flutter in the structural design process. A study is carried out evaluating the effect of leading edge and trailing edge reinforcement on flutter speed and hence demonstrates the ability to increase the flutter speed and satisfy structural design requirements (such as fatigue) while maintaining or even reducing blade mass.

scholarly journals Experimental Investigation of Finite Aspect Ratio Cylindrical Bodies for Accelerated Wind Applications

Fluids ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 25 ◽  
Author(s):  
Michael Parker ◽  
Douglas Bohl
Keyword(s):  
Aspect Ratio ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Cylindrical Body ◽  
Turbine Rotor ◽  
Flow Speed ◽  
The Body ◽  
Rotor Blades ◽  
Wind Turbine Blades ◽  
Smooth Cylinder

The placement of a cylindrical body in a flow alters the velocity and pressure fields resulting in a local increase in the flow speed near the body. This interaction is of interest as wind turbine rotor blades could be placed in the area of increased wind speed to enhance energy harvesting. In this work the aerodynamic performance of two short aspect ratio (AR = 0.93) cylindrical bodies was evaluated for potential use in “accelerated wind” applications. The first cylinder was smooth with a constant diameter. The diameter of the second cylinder varied periodically along the span forming channels, or corrugations, where wind turbine blades could be placed. Experiments were performed for Reynolds numbers ranging from 1 × 105 to 9 × 105. Pressure distributions showed that the smooth cylinder had lower minimum pressure coefficients and delayed separation compared to the corrugated cylinder. Velocity profiles showed that the corrugated cylinder had lower peak speeds, a less uniform profile, and lower kinetic energy flux when compared to the smooth cylinder. It was concluded that the smooth cylinder had significantly better potential performance in accelerated wind applications than the corrugated cylinder.

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