Design Analysis Of Performance And Aerodynamic Loading Of Non Flexible Horizontal Axis Wind Turbines

The objective of this report is to develop simplified methods of determining the performance and aerodynamic loading of non -flexible horizontal axis wind turbines. The first chapter is devoted to a general discussion and background of wind turbine aerodynamics. The second chapter covers horizontal axis wind turbine performance in a uniform wind. A calculation scheme is developed and examples are given. The calculation scheme and program listing are given in detail in Appendik A. The third chapter deals with the analysis and behavior of wind turbines subject to yaw, wind shear and tower shadow. The method of analysis used for yaw has been checked with NACA wind tunnel test data for yawed propellers. Calculation procedures and program listings are given in Appendices B and C.

The exploitation of small horizontal axis wind turbines provides a clean, prospective and viable option for energy supply. Although great progress has been achieved in the wind energy sector, there is still potential space to reduce the cost and improve the performance of small wind turbines. An enhanced understanding of how small wind turbines interact with the wind turns out to be essential. This work investigates the aerodynamic design and analysis of small horizontal axis wind turbine blades via the blade element momentum (BEM) based approach and the computational fluid dynamics (CFD) based approach. From this research, it is possible to draw a series of detailed guidelines on small wind turbine blade design and analysis. The research also provides a platform for further comprehensive study using these two approaches. The wake induction corrections and stall corrections of the BEM method were examined through a case study of the NREL/NASA Phase VI wind turbine. A hybrid stall correction model was proposed to analyse wind turbine power performance. The proposed model shows improvement in power prediction for the validation case, compared with the existing stall correction models. The effects of the key rotor parameters of a small wind turbine as well as the blade chord and twist angle distributions on power performance were investigated through two typical wind turbines, i.e. a fixed-pitch variable-speed (FPVS) wind turbine and a fixed-pitch fixed-speed (FPFS) wind turbine. An engineering blade design and analysis code was developed in MATLAB to accommodate aerodynamic design and analysis of the blades. The linearisation for radial profiles of blade chord and twist angle for the FPFS wind turbine blade design was discussed. Results show that, the proposed linearisation approach leads to reduced manufacturing cost and higher annual energy production (AEP), with minimal effects on the low wind speed performance. Comparative studies of mesh and turbulence models in 2D and 3D CFD modelling were conducted. The CFD predicted lift and drag coefficients of the airfoil S809 were compared with wind tunnel test data and the 3D CFD modelling method of the NREL/NASA Phase VI wind turbine were validated against measurements. Airfoil aerodynamic characterisation and wind turbine power performance as well as 3D flow details were studied. The detailed flow characteristics from the CFD modelling are quantitatively comparable to the measurements, such as blade surface pressure distribution and integrated forces and moments. It is confirmed that the CFD approach is able to provide a more detailed qualitative and quantitative analysis for wind turbine airfoils and rotors. With more advanced turbulence model and more powerful computing capability, it is prospective to improve the BEM method considering 3D flow effects.

Growing energy demand and environmental consciousness have re-evoked human interest in wind energy. As a result, wind is the fastest growing energy source in the world today. Policy frame works and action plans have already been for- lated at various corners for meeting at least 20 per cent of the global energy - mand with new-renewables by 2010, among which wind is going to be the major player. In view of the rapid growth of wind industry, Universities, all around the world, have given due emphasis to wind energy technology in their undergraduate and graduate curriculum. These academic programmes attract students from diver- fied backgrounds, ranging from social science to engineering and technology. Fundamentals of wind energy conversion, which is discussed in the preliminary chapters of this book, have these students as the target group. Advanced resource analysis tools derived and applied are beneficial to academics and researchers working in this area. The Wind Energy Resource Analysis (WERA) software, provided with the book, is an effective tool for wind energy practitioners for - sessing the energy potential and simulating turbine performance at prospective sites.

Printed collection of 105 full-length, peer-reviewed technical papers.

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.

Includes all works deriving from DOE, other related government-sponsored information and foreign nonnuclear information.

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 energy’s bestselling textbook- fully revised. This must-have second edition includes up-to-date data, diagrams, illustrations and thorough new material on: the fundamentals of wind turbine aerodynamics; wind turbine testing and modelling; wind turbine design standards; offshore wind energy; special purpose applications, such as energy storage and fuel production. Fifty additional homework problems and a new appendix on data processing make this comprehensive edition perfect for engineering students. This book offers a complete examination of one of the most promising sources of renewable energy and is a great introduction to this cross-disciplinary field for practising engineers. “provides a wealth of information and is an excellent reference book for people interested in the subject of wind energy.” (IEEE Power & Energy Magazine, November/December 2003) “deserves a place in the library of every university and college where renewable energy is taught.” (The International Journal of Electrical Engineering Education, Vol.41, No.2 April 2004) “a very comprehensive and well-organized treatment of the current status of wind power.” (Choice, Vol. 40, No. 4, December 2002)