Download or read book Analysis and Optimization of Shrouded Horizontal Axis Wind Turbines written by Tariq Abdulsalam Khamlaj and published by . This book was released on 2018 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: So-called wind-lens turbines offer the potential for improved energy efficiency and better suitability for urban and suburban environments compared to unshrouded or bare wind turbines. Wind-lenses, which are typically comprised of a diffuser shroud equipped with a flange, can enhance the wind velocity at the rotor plane due to the generation of a lower back pressure. This work comprises of two main studies which aim to develop fast and accurate simulation tools for the performance prediction and design of shrouded horizontal axis wind turbines. In the first study, a low-order theoretical model of ducted turbines is developed to establish a better understanding of the basic aerodynamics of shrouded wind turbines. Then a cost-effective CFD tool coupled with a multi-objective genetic algorithm is developed and employed to improve the performance of shrouded wind turbines. A low-order semi empirical model, which offers performance prediction for the power and thrust coefficients, is developed and applied to shrouded turbines. This 1D model is based on assumptions and approximations to calculate optimal power coefficients and power extraction, as well as augmentation ratios. It is revealed that the power enhancement is proportional to the mass stream rise produced by the nozzle diffuser-augmented wind turbine (NDAWT). Such mass flow rise can only be accomplished through two essential principles: an increase in the area ratios and/or by reducing the negative back pressure at the exit. The thrust coefficient for optimal power production of a conventional bare wind turbine is known to be 8/9, whereas the theoretical analysis of the NDAWT predicts an ideal thrust coefficient either lower or higher than 8/9 depending on the back-pressure coefficient at which the shrouded turbine operates. Computed performance expectations demonstrate a good agreement with numerical and experimental results, and it is demonstrated that much larger power coefficients than for traditional wind turbines are achievable. Lastly, the developed model is found to be very well suited for the preliminary design of shrouded wind turbines where typically many trade-off studies need to be conducted inexpensively. Then a higher fidelity model is developed and implemented to calculate the power, thrust, and drag coefficients by solving the Reynolds-averaged Navier-Stokes (RANS) equations with the k-epsilon turbulence model for the flow within and around diffuser augmented wind turbines using the open source software OpenFOAM. To reduce the computational cost, the turbine rotor itself is modeled by incorporating blade element momentum body forces into the RANS equations. Realistic rotor data for the sectional lift and drag coefficients for all angles of attacks are utilized via look-up tables. Grid convergence studies for verification and comparisons with experiments for validation are carried out to demonstrate that the adopted methodology is able to accurately predict the performance of a wind-lens prior to performing shape optimizations. Finally, the wind-lens performance is increased by designing the shroud and wind turbine shapes as well as flange height through an optimization process that seeks to maximize the power while minimizing drag and thrust forces. The employed optimizer is a multi-objective genetic algorithm (MOGA). Bezier curves are used to define the chord and twist distribution of the turbine blades and a piece-wise quadratic polynomial is utilized to define the shroud shape. It is demonstrated that the resulting optimal designs yield significant improvements in the output power.

Download or read book CFD Analysis of the Characteristics of a Shrouded Turbine written by Maximilian Ludwig Ganis and published by diplom.de. This book was released on 2003-07-25 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inhaltsangabe:Abstract: Wind energy is an increasingly import source of renewable, clean energy. In spite of this, only the methods and the materials of construction have improved over time, while the basic working principle of the wind turbine is still the same as it was centuries ago. In this thesis we have increased the power of a wind turbine by a factor of 4 in a fluid dynamic simulation, using a very simple external shroud system. We have also extended the theory of wind turbines (limit of Betz), to include this new kind of device and show why past attempts to augment the power of a wind turbine by means of shroud systems have failed. A detailed analysis of the device and its functioning principle is presented in this thesis - optimization studies need to be done in the future. Inhaltsverzeichnis:Table of Contents: AbstractI IndexII List of FiguresIV List of SymbolsVI Introduction1 1.Theory of Wind Turbines5 1.1Introduction5 1.2The Betz Law6 1.3Aerodynamics of the rotor13 1.4Rotor Power Characteristics18 1.5Number of Rotor Blades20 1.6Horizontal Axis Wind Turbines (HAWT)22 1.7Shrouded / Ducted Wind Turbines28 1.7.1Ducted Rotor29 1.7.2Turbine with a Diffuser Duct29 2.Methodology33 2.1Introduction33 2.2Computational Domain34 2.3Computational Code41 2.3.1Conservation Equations42 2.3.2K-Epsilon Turbulence Model43 2.3.3Discretization of the Conservation Equations45 2.4MFR - Multiple Frame of Reference45 2.5Parallel Processing46 2.6Simulations47 3.Results48 3.1Introduction48 3.2Conventional Turbine49 3.2.1Velocity Field49 3.2.2Static Pressure Field52 3.2.3Total Pressure Field53 3.2.4Power of the Conventional Turbine55 3.2.5Energy and Momentum Transfer57 3.3Shrouded Turbine59 3.3.1Velocity Field59 3.3.2Static Pressure Field62 3.3.3Total Pressure Field63 3.3.4Power of the Shrouded Turbine65 3.3.5Energy and Momentum Transfer66 3.3.6The Betz Limit68 3.3.7Cross Check Analysis with Traditional Shrouded Turbines69 Conclusions72 Bibliography73 Acknowledgments

Download or read book Numerical Modeling and Optimization of Power Generation from Shrouded Wind Turbines written by Tudor F. Foote and published by . This book was released on 2011 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, it has been theoretically suggested by some researchers that the power coefficient of a wind turbine can be increased beyond the Betz limit for a bare turbine by enclosing the turbine with a duct. In this thesis, this potential for increases in power generation by adding a shroud around a turbine is investigated using numerical flow modeling. Two configurations for ducted turbines are considered for numerical simulations and optimization. The first configuration considers shrouds for standard horizontal axis wind turbines. Several turbine diameters, wind speeds, and shroud sizes are considered. The results show that shrouding can almost double the power that would be generated by a bare turbine. The second configuration considers the potential of converting abandoned or unused farm silos into solar chimneys with low cost shape modification of the chimney to further augment the power generation. The most effective, simple and low cost shape modification is found to be a diffuser added to the top of the silo, which can increase the power output by nearly 50%. Increasing the buoyancy effect by heating the air at the base of the silo can further increase the power output by a significant amount, as much as 50%. It should be noted that in this configuration, the effect of cross flow wind at the exit of the diffuser can have a negative effect on the generated wind power; however, it is surmised to be small. Both these configurations are analyzed by employing computational fluid dynamics flow solver, which solves the Reynolds-Averaged Navier-Stokes equations, in conjunction with a two equation k-epsilon turbulence model. The turbine is modeled as an actuator disk neglecting the rotational effects. The diffuser shapes in both the configurations are optimized using a genetic algorithm. The computations show that the shrouded turbines can generate greater power than that generated by the bare turbines and should be considered for small and medium size turbines. Further investigation is needed in the overall economic benefit considering the initial investment, maintenance and life cycle costs. The technical feasibility of shrouding a turbine and the structural integrity of a shrouded turbine are also major considerations.

Download or read book Aerodynamics of Wind Turbines written by Sven Schmitz and published by John Wiley & Sons. This book was released on 2019-07-31 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review of the aerodynamics, design and analysis, and optimization of wind turbines, combined with the author’s unique software Aerodynamics of Wind Turbines is a comprehensive introduction to the aerodynamics, scaled design and analysis, and optimization of horizontal-axis wind turbines. The author –a noted expert on the topic – reviews the fundamentals and basic physics of wind turbines operating in the atmospheric boundary layer. He then explores more complex models that help in the aerodynamic analysis and design of turbine models. The text contains unique chapters on blade element momentum theory, airfoil aerodynamics, rotational augmentation, vortex-wake methods, actuator-line modeling, and designing aerodynamically scaled turbines for model-scale experiments. The author clearly demonstrates how effective analysis and design principles can be used in a wide variety of applications and operating conditions. The book integrates the easy-to-use, hands-on XTurb design and analysis software that is available on a companion website for facilitating individual analyses and future studies. This component enhances the learning experience and helps with a deeper and more complete understanding of the subject matter. This important book: Covers aerodynamics, design and analysis and optimization of wind turbines Offers the author’s XTurb design and analysis software that is available on a companion website for individual analyses and future studies Includes unique chapters on blade element momentum theory, airfoil aerodynamics, rotational augmentation, vortex-wake methods, actuator-line modeling, and designing aerodynamically scaled turbines for model-scale experiments Demonstrates how design principles can be applied to a variety of applications and operating conditions Written for senior undergraduate and graduate students in wind energy as well as practicing engineers and scientists, Aerodynamics of Wind Turbines is an authoritative text that offers a guide to the fundamental principles, design and analysis of wind turbines.

Download or read book Review of Research in Horizontal Axis Wind Turbines written by Ali Sheikh and published by . This book was released on 2019-11-05 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Towards Multidisciplinary Design Optimization Capability of Horizontal Axis Wind Turbines written by Michael Kenneth McWilliam and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Research into advanced wind turbine design has shown that load alleviation strategies like bend-twist coupled blades and coned rotors could reduce costs. However these strategies are based on nonlinear aero-structural dynamics providing additional benefits to components beyond the blades. These innovations will require Multi-disciplinary Design Optimization (MDO) to realize the full benefits.This research expands the MDO capabilities of Horizontal Axis Wind Turbines. The early research explored the numerical stability properties of Blade Element Momentum (BEM) models. Then developed a provincial scale wind farm siting models to help engineers determine the optimal design parameters. The main focus of this research was to incorporate advanced analysis tools into an aero-elastic optimization framework. To adequately explore advanced designs with optimization, a new set of medium fidelity analysis tools is required. These tools need to resolve more of the physics than conventional tools like (BEM) models and linear beams, while being faster than high fidelity techniques like grid based computational fluid dynamics and shell and brick based finite element models.

Download or read book CFD based Analysis and Optimization of Wind Boosters for Low Speed Vertical Axis Wind Turbines written by Natapol Korprasertsak and published by . This book was released on 2015 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Towards a Virtual Platform for Aerodynamic Design Performance Assessment and Optimization of Horizontal Axis Wind Turbines written by Daniel Martínez Valdivieso and published by . This book was released on 2017 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis focuses on the study and improvement of the techniques involved on a virtual platform for the simulation of the Aerodynamics of Horizontal Axis Wind Turbines, with the ultimate objective of making Wind Energy more competitive. Navier-Stokes equations govern Aerodynamics, which is an unresolved and very active field of research due to the current inability to capture the relevant the scales both in time and space for nowadays industrial-size machines (with rotors over 100 m in diameter). Therefore, there is a need to aim at a combination of engineering and scientific models. The structure of this thesis is designed in accordance to the previous fact, so there are clearly two parts or approaches within the conducted research: zero dimensional models and CFD based analysis. For those zero-dimensional and (computationally) cheaper approach, the efforts done were the next: visualization and side improvements on the well known BEM code for pre-design purposes; designing an AeroElectric coupled algorithm to merge BEM with simple generator models that exclude details on electric circuits; designing a C++ code to study the dynamics of wind turbines coupling different component models; implementation of energy production based algorithms to optimize blades pre-designed with BEM, given the wind resources at the real location. CFD-based analysis are meant to be the tools to design wind turbines in the future. Nowadays and for the years to come, they are and will be under ongoing research. The efforts done to this rescpect have been the next: exploration, implementation and analysis of Non-Inertial Reference Frame, Immersed Boundary Method, Sliding Meshes. Additionally, Adaptive Mesh Refinement and Wall Model LES methods have been explored too.

Download or read book Probabilistic Design Optimization of Horizontal Axis Wind Turbine Rotors written by Caboni Marco and published by . This book was released on 2016 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analysis of the Control Problem for Horizontal Axis Wind Turbines written by Sven Erik Mattsson and published by . This book was released on 1983 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reliability Based Optimization of Floating Wind Turbine Support Structures written by Mareike Leimeister and published by Springer Nature. This book was released on 2023-01-01 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book pursues the ambitious goal of combining floating wind turbine design optimization and reliability assessment, which has in fact not been done before. The topic is organized into a series of very ambitious objectives, which start with an initial state-of-the-art review, followed by the development of high-fidelity frameworks for a disruptive way to design next generation floating offshore wind turbine (FOWT) support structures. The development of a verified aero-hydro-servo-elastic coupled numerical model of dynamics for FOWTs and a holistic framework for automated simulation and optimization of FOWT systems, which is later used for the coupling of design optimization with reliability assessment of FOWT systems in a computationally and time-efficient manner, has been an aim of many groups internationally towards implementing a performance-based/goal-setting approach in the design of complex engineering systems. The outcomes of this work quantify the benefits of an optimal design with a lower mass while fulfilling design constraints. Illustrating that comprehensive design methods can be combined with reliability analysis and optimization algorithms towards an integrated reliability-based design optimization (RBDO) can benefit not only the offshore wind energy industry but also other applications such as, among others, civil infrastructure, aerospace, and automotive engineering.

Download or read book Review of Research and Development in the Field of Horizontal Axis Wind Turbines written by Ali Rashwan and published by Independently Published. This book was released on 2019-07-20 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Lifting Surface Performance Analysis for Horizontal Axis Wind Turbines written by Dianna S. Kocurek and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quasi static Structural Analysis of a Vertical axis Wind Turbine written by Kevin Lee Jackson and published by . This book was released on 1984 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Methods for Design Analysis of Horizontal Axis Wind Turbines written by Rene H. Miller and published by . This book was released on 1978 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Methods for Design Analysis of Horizontal Axis Wind Turbines Wind Energy Conversion written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The material is presented as far as possible in the form of charts, either tables or graphs, from which specific design information may be selected or trends determined without the need for computational facilities. For design purposes, or when attempting to correct a design deficiency, trends are frequently more useful than absolute information. Since it is impossible to cover all possible configurations for a system with as many parameters as a wind turbine, interpolation will be necessary in many cases.

Download or read book Lifting Surface Performance Analysis for Horizontal Axis Wind Turbines written by Dianna S. Kocurek and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: