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Author: Myra Louise Blaylock Publisher: ISBN: 9781267967572 Category : Languages : en Pages :
Book Description
A fast, efficient way to control loads on industrial scale turbines is important for the growth of the wind industry. Active Aerodynamic Load Control (AALC) is one area which addresses this need. In particular, microjets, which are pneumatic jets located at the trailing edge of a wind turbine blade and blow perpendicular to the blade surface, are a possible AALC candidate. First, the Computational Fluid Dynamics (CFD) solver OVERFLOW is used to explore the effects of a microjet on lift, drag, and pitching moment. Then the interaction between an aerodynamic disturbance and an airfoil equipped with a microjet is modeled. The object of this dissertation is to investigate microtabs as viable AALC devices by presenting their aerodynamic properties and testing whether a proportional-integral (PI) controlled jets can alleviate loads caused by wind gusts. The use of CFD to simulate a microjet is validated by comparing the results to both previous experiments found in the literature as well as wind tunnel tests completed at UC Davis. The aerodynamic effectiveness of the jet is investigated as a function of various parameters such as Reynolds number, angle of attack, and the momentum coefficient of the jet. The effects of the microjet are found to be very similar to another AALC device, the microtab. An aerodynamic disturbance is simulated, and a control algorithm which is incorporated into the OVERFLOW code is used to activate the microjet, thus reducing the change of the blade load due to the gust. Finally, a more realistic model is made by adding both a linear and a torsional spring and damper to represent the blade movement. This two-degree of freedom system shows that during a gust the vertical blade movement is reduced when the microjets are activated. Microjets are found to work well to alleviate the changes in aerodynamic loads felt by the airfoil, and are therefore a good candidate for a practical AALC device. However, further investigation is needed in the areas of aeroacoustics, system energy requirements, and logistics of implementation.
Author: Myra Louise Blaylock Publisher: ISBN: 9781267967572 Category : Languages : en Pages :
Book Description
A fast, efficient way to control loads on industrial scale turbines is important for the growth of the wind industry. Active Aerodynamic Load Control (AALC) is one area which addresses this need. In particular, microjets, which are pneumatic jets located at the trailing edge of a wind turbine blade and blow perpendicular to the blade surface, are a possible AALC candidate. First, the Computational Fluid Dynamics (CFD) solver OVERFLOW is used to explore the effects of a microjet on lift, drag, and pitching moment. Then the interaction between an aerodynamic disturbance and an airfoil equipped with a microjet is modeled. The object of this dissertation is to investigate microtabs as viable AALC devices by presenting their aerodynamic properties and testing whether a proportional-integral (PI) controlled jets can alleviate loads caused by wind gusts. The use of CFD to simulate a microjet is validated by comparing the results to both previous experiments found in the literature as well as wind tunnel tests completed at UC Davis. The aerodynamic effectiveness of the jet is investigated as a function of various parameters such as Reynolds number, angle of attack, and the momentum coefficient of the jet. The effects of the microjet are found to be very similar to another AALC device, the microtab. An aerodynamic disturbance is simulated, and a control algorithm which is incorporated into the OVERFLOW code is used to activate the microjet, thus reducing the change of the blade load due to the gust. Finally, a more realistic model is made by adding both a linear and a torsional spring and damper to represent the blade movement. This two-degree of freedom system shows that during a gust the vertical blade movement is reduced when the microjets are activated. Microjets are found to work well to alleviate the changes in aerodynamic loads felt by the airfoil, and are therefore a good candidate for a practical AALC device. However, further investigation is needed in the areas of aeroacoustics, system energy requirements, and logistics of implementation.
Author: Owen Francisco Hurley Publisher: ISBN: 9781321806397 Category : Languages : en Pages :
Book Description
A computational investigation was performed analyzing the potential for reduction in wind turbine fatigue utilizing microjets for active aerodynamic load control. Increasing size of wind turbine rotors requires methods for reduction of critical fatigue and extreme loads. Active Aerodynamic Load Control provides local control of aerodynamic properties utilizing active flow control devices to alter loads along the wind turbine span to reduce total loading. These devices respond quickly allowing for on demand control of aerodynamic loading. Microjets have shown promising aerodynamic characteristics but require pneumatic input to operate which poses as a potentially difficult to overcome obstacle to implementation in wind turbine applications where Cost of Energy (COE) is critical. This thesis explores systems with both passive and active driven pneumatic systems comparing the energy input to the potential for fatigue reduction. Analysis of a wide range of potential configurations of microjets along the NREL Baseline Offshore 5-MW Reference Wind Turbine is conducted. A program developed to calculate flow potential at each configuration is integrated with WT-Perf, a BEM horizontal wind turbine performance simulation tool that is used to calculate the reduction in steady state flapwise root bending moment. Reduction in steady state flapwise root bending moment across the wind turbine's operating range is the primary metric for comparing the success of each microjet system configuration. Passive systems in which no externally driven pneumatic devices, such as blowers, are considered along with active systems which include external means of driving flow through the microjet. The findings in this thesis indicate that the optimum location for a microjet system on the NREL 5-MW begins approximately halfway down the span of the wind turbine blade extending a length of approximate one quarter of the total blade length. With a passive system, maximum reduction in flapwise root bending moment at rated wind speed was approximately 4.5% of the total flapwise moment which increases to 6% with the addition of a 5kPa blower.
Author: Wen Zhong Shen Publisher: MDPI ISBN: 3039215248 Category : Technology & Engineering Languages : en Pages : 410
Book Description
Wind turbine aerodynamics is one of the central subjects of wind turbine technology. To reduce the levelized cost of energy (LCOE), the size of a single wind turbine has been increased to 12 MW at present, with further increases expected in the near future. Big wind turbines and their associated wind farms have many advantages but also challenges. The typical effects are mainly related to the increase in Reynolds number and blade flexibility. This Special Issue is a collection of 21 important research works addressing the aerodynamic challenges appearing in such developments. The 21 research papers cover a wide range of problems related to wind turbine aerodynamics, which includes atmospheric turbulent flow modeling, wind turbine flow modeling, wind turbine design, wind turbine control, wind farm flow modeling in complex terrain, wind turbine noise modeling, vertical axis wind turbine, and offshore wind energy. Readers from all over the globe are expected to greatly benefit from this Special Issue collection regarding their own work and the goal of enabling the technological development of new environmentally friendly and cost-effective wind energy systems in order to reach the target of 100% energy use from renewable sources, worldwide, by 2050
Author: E. Obert Publisher: IOS Press ISBN: 1607504073 Category : Science Languages : en Pages : 656
Book Description
The origin of Aerodynamic Design of Transport Aircraft stems from the time when the author was appointed part-time professor in the Aerospace Faculty of Delft University of Technology. At the time his main activities were those of leading the departments of Aerodynamics, Performance and Preliminary Design at Fokker Aircraft Company. The groundwork for this book started in 1987 as a series of lecture notes consisting mainly of pictorial material with a minimum of English explanatory text. After the demise of Fokker in 1996 one feared that interest in aeronautical engineering would strongly diminish. As a result of this, the course was discontinued and the relationship between the author and the faculty came to an end. Two years later the situation was reappraised, and the interest in aeronautical engineering remained, so the course was reinstated with a former Fokker colleague Ronald Slingerland as lecturer. The lecture notes from these courses form the foundation of this publication.
Author: Holger Babinsky Publisher: Cambridge University Press ISBN: 1139498649 Category : Technology & Engineering Languages : en Pages : 481
Book Description
Shock wave-boundary-layer interaction (SBLI) is a fundamental phenomenon in gas dynamics that is observed in many practical situations, ranging from transonic aircraft wings to hypersonic vehicles and engines. SBLIs have the potential to pose serious problems in a flowfield; hence they often prove to be a critical - or even design limiting - issue for many aerospace applications. This is the first book devoted solely to a comprehensive, state-of-the-art explanation of this phenomenon. It includes a description of the basic fluid mechanics of SBLIs plus contributions from leading international experts who share their insight into their physics and the impact they have in practical flow situations. This book is for practitioners and graduate students in aerodynamics who wish to familiarize themselves with all aspects of SBLI flows. It is a valuable resource for specialists because it compiles experimental, computational and theoretical knowledge in one place.
Author: Myra Louise Blaylock
Author: Myra Louise Blaylock
Author: Owen Francisco Hurley
Author: American Institute of Aeronautics and Astronautics
Author: Karen A. Deere
Author: 
Author: Andrew R. Fenlon
Author: Quian Liu
Author: Wen Zhong Shen
Author: E. Obert
Author: Holger Babinsky