Aerodynamic Performance Of A Horizontal Axis Wind Turbine With Forward And Backward Swept Blades

Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design a classical pitch and torque regulator to control rotational speed and power, while the section on structural dynamics has been extended with a simplified mechanical system explaining the phenomena of forward and backward whirling modes. Readers will also benefit from a new chapter on Vertical Axis Wind Turbines (VAWT). Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method is also covered, as are eigenmodes and the dynamic behaviour of a turbine. The book describes the effects of the dynamics and how this can be modelled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Furthermore, it examines how to calculate the vibration of the whole construction, as well as the time varying loads and global case studies.

This book deals with horizontal-axis wind turbine aerodynamic performance prediction methods. It focuses on the traditional and newly-developed methods for the wind turbine aerodynamic performance calculation. The fundamental theories of fluid mechanics essential for understanding the other parts of this book are firstly introduced in Part I, followed by the blade element momentum theory in Part II, with special attentions to a systematic review of various correction models. Part III is mainly about the prescribed and free vortex wake methods, while the state-of-art computational fluid dynamics (CFD) methods are detailed in Part IV. Part III thoroughly describes the prescribed and free vortex wake methods which are still of great importance towards realistic investigation of wind turbine performance. Despite the highly computational cost, the CFD methods in Part IV have received increasing interest from the academic community since they provide more detailed information about the flow field around the wind turbine. This has shed a light in combination with the correction models introduced in Part II on more advanced research for wind turbine. This book is intended for researchers and students interested in aerodynamics of wind turbine and is particularly suitable for practicing engineers in wind energy. Readers can gain a comprehensive understanding in both classical and up-to-date methods for the study of wind turbine aerodynamics. The authors hope that this book can promote the research and development of wind turbines.

Focusing on Aerodynamics of Wind Turbines with topics ranging from Fundamental to Application of horizontal axis wind turbines, this book presents advanced topics including: Basic Theory for Wind turbine Blade Aerodynamics, Dynamics-Based Health Monitoring and Control of Wind Turbine Rotors, Experimental Testing of Wind Turbines Using Wind Tunnels with an Emphasis on Small-Scale Wind Turbines Under Low-Reynolds Numbers, Computational Methods, Ice Accretion for Wind Turbines and Influence of Some Parameters, and Special Structural Reinforcement Technique for Wind Turbine Blades. Consequently, for these reasons, analysis of wind turbines will attract readers not only from the wind energy community but also in the gas turbines heat transfer and fluid mechanics community.

Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its second edition, it has been entirely updated and substantially extended to reflect advances in technology, research into rotor aerodynamics and the structural response of the wind turbine structure. Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method is also covered, as are eigenmodes and the dynamic behaviour of a turbine. The new material includes a description of the effects of the dynamics and how this can be modelled in an ?aeroelastic code?, which is widely used in the design and verification of modern wind turbines. Further, the description of how to calculate the vibration of the whole construction, as well as the time varying loads, has been substantially updated.

The following study is a compilation on the research and development in the field of horizontal axis wind turbines. It is known that in the wind energy industry, the horizontal axis wind turbines take lead over all other types. They are applicable on the domestic level too but this work focuses on the large scale machines. A driving factor is that they are a source of green energy. The other reason is that the horizontal axis wind turbines are more efficient than the vertical axis wind turbines. They have a number of mechanical components but the ones emphasized in this study are primarily the aerodynamics related ones. To confine, rotor has been the major area of study and research. The vital part is blade, so, the work is majorly around performance aspects of the blade. An effort is made to explore the possibilities of improvement in blade design variables. A cursory investigation is also done on another related structural component, tower, which affects the performance of rotor. A brief review of the horizontal axis wind turbine life cycle is also included in order to mark the environmental implications of it as a product. Analyses of the researchers have been studied and many important and recent findings have been highlighted. Modern techniques which are used for the enhancement of design variables, are investigated and recent works on correction factors for the governing equations have been discussed. The aim of this study is to review the current research on the HAWTs. The purpose is to explore the possibilities toward the improvement of design variables relating to the aerodynamic performance. To mention explicitly, the study focuses on the improvement in the design aspects of rotor which predominantly depends on the blade. The intent is to investigate the pros and cons of altering various parameters of the blade; aiming at the improved performance, keeping in view the material, manufacturing and the environmental aspects of the stated WTs as a product.The work starts with the overview of the wind energy capacity of various countries, to have surface knowledge of the importance of the technology. The study covers the basic features of HAWTs as well as VAWTs, that is, the other wind energy technology. A basic review is had on the various relevant aspects of the wind farm which directly affect the performance of HAWTs. To investigate HAWT as a product; its environmental impacts have been estimated in order to justify the technology. Starting from the aerodynamic efficiency limit, that is, Betz's limit, various governing equations previously derived have been highlighted and along with that the correction factors have been discussed which refine the analyses based on the applied theories.An investigation on the performance of the blade, as the main part of the rotor, has been done. Correlation of various design variables has been observed. Some findings relevant to the performance improvement have been stated. Novel approaches like using VAWTs as the supporting machines for HAWTs and having multi rotor WTs have been studied to see if they are viable at some scale of power generation. There is a limit to the optimization of the blade that the researchers can do. So, according to applications, the workability of the stated novel approaches is studied as well as recommended for future research.

Author's abstract: The demand for wind energy as a renewable source is rising substantially. A growing interest exists in utilizing potential energy conversion applications in areas with less powerful and less consistent wind conditions. In these areas, vertical-axis wind turbines (VAWTs) possess several advantages over the conventional horizontal-axis type. Savonius turbines are drag-based rotors which operate due to a pressure difference between the advancing and retreating blades. These turbines are simpler in design, less expensive to install, non-dependent of wind direction, and more efficient in lower wind speeds. In the present study, six different rotor designs with equal swept areas are analyzed with wind tunnel testing and numerical simulations. These models include a traditional Savonius with 2 blades, “CC” model, “QM” model, and 90 degree helical twist models with 2, 3, and 4 blades. The models were designed using the CAD software SolidWorks. Due to the complex geometry of the blades, the physical models were then 3D printed for experimental testing. Subsonic, open-type wind tunnel testing was used for measuring RPM and reactional torque over a range of wind speeds. For the numerical approach, ANSYS Fluent simulations were used for analyzing aerodynamic performance by utilizing moving reference frame and sliding mesh model techniques. For the models with helical twist, the cross-sections of the blades varies in the Y-direction. Because of this, a 3-dimensional and transient method was used for accurately solving torque and power coefficients. The 5 new rotor geometries included in the study create a center of pressure further from the axis of rotation causing greater torque on the turbine shaft, compared to the traditional Savonius turbine. The CC and QM cross-sections reduce the total range of negative torque on the blades by 20 degrees, compared to the traditional Savonius model. Helical designs better spread the applied torque over a complete revolution resulting in positive torque over all operational angles. Helical models with 2 and 3 blades have the best self-starting capability in low wind speeds. Under no generator loading, Helical3 begins rotation of 35 RPM at just 1.4 m/s wind velocity. The highest power coefficient in the study is achieved, both experimentally and numerically, by the helical VAWT with 2 blades. Averaged over one full rotation, a maximum power coefficient of 0.14 is observed with the Helical2 model at tip-speed ratio of 0.475.

Wind power is an increasingly significant renewable energy resource, producing no environmentally damaging CO2 emissions. The efficient production of electricity by wind turbines relies on aerodynamics: Aerodynamics of Wind Turbines provides the fundamental solutions to efficient wind turbine design. Following a historical introduction, Part 1 of Aerodynamics of Wind Turbines is concerned with basic rotor aerodynamics, while Part 2 deals with structural aspects of the wind turbine and calculation of the loads on it. Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method is also covered, as are eigenmodes and the dynamic behavior of a turbine. Aerodynamics of Wind Turbines is an essential reference for both engineering students and others with a professional or academic interest in the physics and technologies behind horizontal axis wind turbines. It will provide a sound understanding of the mechanisms behind the generation of forces on a wind turbine.