Academic literature on the topic 'Airfoil profiles'
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Journal articles on the topic "Airfoil profiles"
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Zhang, Qiang, and Phillip M. Ligrani. "Wake Turbulence Structure Downstream of a Cambered Airfoil in Transonic Flow: Effects of Surface Roughness and Freestream Turbulence Intensity." International Journal of Rotating Machinery 2006 (2006): 1–12. http://dx.doi.org/10.1155/ijrm/2006/60234.
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The wake turbulence structure of a cambered airfoil is studied experimentally, including the effects of surface roughness, at different freestream turbulence levels in a transonic flow. As the level of surface roughness increases, all wake profile quantities broaden significantly and nondimensional vortex shedding frequencies decrease. Freestream turbulence has little effect on the wake velocity profiles, turbulence structure, and vortex shedding frequency, especially downstream of airfoils with rough surfaces. Compared with data from a symmetric airfoil, wake profiles produced by the cambered airfoils also have significant dependence on surface roughness, but are less sensitive to variations of freestream turbulence intensity. The cambered airfoil also produces larger streamwise velocity deficits, and broader wakes compared to the symmetric airfoil.
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Xudong, Wang, Wang Licun, and Xia Hongjun. "An Integrated Method for Designing Airfoils Shapes." Mathematical Problems in Engineering 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/838674.
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A new method for designing wind turbine airfoils is presented in this paper. As a main component in the design method, airfoil profiles are expressed in a trigonometric series form using conformal transformations and series of polynomial equations. The characteristics of the coefficient parameters in the trigonometric expression for airfoils profiles are first studied. As a direct consequence, three generic airfoil profiles are obtained from the expression. To validate and show the generality of the trigonometric expression, the profiles of the NACA 64418 and S809 airfoils are expressed by the present expression. Using the trigonometric expression for airfoil profiles, a so-called integrated design method is developed for designing wind turbine airfoils. As airfoil shapes are expressed with analytical functions, the airfoil surface can be kept smooth in a high degree. In the optimization step, drag and lift force coefficients are calculated using the XFOIL code. Three new airfoils CQ-A15, CQ-A18, and CQ-A21 with a thickness of 15%, 18%, and 21%, respectively, are designed with the new integrated design method.
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Kumar, P. Madhan, and Abdus Samad. "Effect of Blade Profiles on the performance of Bidirectional Wave Energy Turbine." MATEC Web of Conferences 172 (2018): 06002. http://dx.doi.org/10.1051/matecconf/201817206002.
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To fulfill the ever growing demands of world energy consumption, the wave energy should be extracted economically. The oscillating water column is most commonly used to xtract energy from waves. It consists of a chamber in which waves drives the entrapped air column to rotate the Wells turbine. The Wells turbine is a self-rectifying low-pressure axial reaction turbine with 90ο stagger angle. These turbines consist of symmetrical airfoil profile to achieve unidirectional rotation for the bi-directional airflow. The turbine performance predominantly depends on the aerodynamic characteristics of the airfoil profile used. In this study, the performance of Wells turbine with various symmetrical airfoil profiles was analysed using ANSYS CFX 14.5. The CFD analysis was performed by solving three dimensional steady Reynolds averaged Navier-Stokes equation with k-ω SST turbulence closure model. The reference geometry has NACA0015 as blade profile and the CFD results were compared with the experimental values. The performance characteristics of the new airfoil profiles were compared with the reference case to analyse the suitability of airfoils in wave energy extraction. The NACA0021 airfoil profile showed better performance in the post-stall regime compared to the NACA0015 and the S1046 airfoil profiles.
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Xie, Yonghui, Kun Lu, Di Zhang, and Gongnan Xie. "Computational Analysis of Propulsion Performance of Modified Pitching Motion Airfoils in Laminar Flow." Mathematical Problems in Engineering 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/420436.
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The thrust generation performance of airfoils with modified pitching motion was investigated by computational fluid dynamics (CFD) modeling two-dimensional laminar flow at Reynolds number of 104. The effect of shift distance of the pitch axis outside the chord line(R), reduced frequency(k), pitching amplitude(θ), pitching profile, and airfoil shape (airfoil thickness and camber) on the thrust generated and efficiency were studied. The results reveal that the increase inRandkleads to an enhancement in thrust generation and a decrease in propulsive efficiency. Besides, there exists an optimal range ofθfor the maximum thrust and the increasingθinduces a rapid decrease in propulsive efficiency. Six adjustable parameters(K)were employed to realize various nonsinusoidal pitching profiles. An increase inKresults in more thrust generated at the cost of decreased propulsive efficiency. The investigation of the airfoil shape effect reveals that there exists an optimal range of airfoil thickness for the best propulsion performance and that the vortex structure is strongly influenced by the airfoil thickness, while varying the camber or camber location of airfoil sections offers no benefit in thrust generation over symmetric airfoil sections.
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Duz, Hasan, and Serkan Yildiz. "Numerical Performance Analyses of Different Airfoils for Use in Wind Turbines." International Journal of Renewable Energy Development 7, no. 2 (July 10, 2018): 151–57. http://dx.doi.org/10.14710/ijred.7.2.151-157.
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This study numerically investigated different types of high-performance airfoils in order to increase the efficiency of wind turbines. Performances of five airfoil types were numerically simulated at different attack angles (0 ° <α <20 °) and at different wind speeds (4, 8, 16 and 32 m/s). Numerical analysis shows that all airfoils achieve the highest performance at attack angles between 4o and 7o. Results also show that the performance of all airfoils increases in direct proportion to increase in wind speed with a low gradient. A new hybrid airfoil was generated by combining lower and upper surface coordinates of two high-performance airfoils which achieved the better results in pressure distribution. Numerical analysis shows that the hybrid airfoil profile performs up to 6% better than other profiles at attack angles between 4o and 7o while it follows the maximum performance curves closely at other attack anglesArticle History: Received January 16th 2018; Received in revised form June 5th 2018; Accepted June 15th 2018; Available onlineHow to Cite This Article: Duz, H and Yildiz, S. (2018) Numerical Performance Analyses of Different Airfoils for Use in Wind Turbines. Int. Journal of Renewable Energy Development, 7(2), 151-157.https://doi.org/10.14710/ijred.7.2.151-157
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Sonoda, Toyotaka, and Heinz-Adolf Schreiber. "Aerodynamic Characteristics of Supercritical Outlet Guide Vanes at Low Reynolds Number Conditions." Journal of Turbomachinery 129, no. 4 (August 19, 2006): 694–704. http://dx.doi.org/10.1115/1.2720868.
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As a part of an innovative aerodynamic design concept for a single stage low pressure turbine, a high turning outlet guide vane is required to remove the swirl from the hot gas. The airfoil of the vane is a highly loaded compressor airfoil that has to operate at very low Reynolds numbers (Re∼120,000). Recently published numerical design studies and experimental analysis on alternatively designed airfoils showed that blade profiles with an extreme front loaded pressure distribution are advantageous for low Reynolds number conditions. The advantage even holds true for an increased inlet Mach number at which the peak Mach number on the airfoils reaches and exceeds the critical conditions (Mss>1.0). This paper discusses the effect of the inlet Mach number and Reynolds number on the cascade performance for both a controlled diffusion airfoil (CDA) (called baseline) and a numerically optimized front loaded airfoil. The results show that it is advantageous to design the profile with a fairly steep pressure gradient immediately at the front part in order to promote early transition or to prevent too large laminar—even shock induced—separations with the risk of a bubble burst. Profile Mach number distributions and wake traverse data are presented for design and off-design conditions. The discussion of Mach number distributions and boundary layer behavior is supported by numerical results obtained from the blade-to-blade flow solver MISES.
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Seralathan, Sivamani, T. Micha Premkumar, S. Thangavel, and G. P. Pradeep. "Numerical Studies on the Effect of Cambered Airfoil Blades on Self-Starting of Vertical Axis Wind Turbine Part 2: NACA 0018 and NACA 63415." Applied Mechanics and Materials 787 (August 2015): 245–49. http://dx.doi.org/10.4028/www.scientific.net/amm.787.245.
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NACA 0012 and NACA 4415 were discussed in Part 1 of the paper to study the capabilities of the airfoil blades by considering the effect of cambered airfoil blade on self-starting of vertical axis wind turbine. The numerical studies are carried out to identify self-starting capability of the airfoil using CFD analysis by studying the flow field over the vertical axis wind turbine blades. In this Part 2 paper, detailed numerical results of asymmetrical NACA 0018 and cambered airfoil NACA 63415 are presented. The lift force generated and the rotor torque induced varies with angle of attack. Based on the contours of static pressure and velocity distribution as well as based on the torque induced in the flow field over blade profiles, NACA 0018 is found to be better compared to cambered airfoil. Even though the lift force for cambered airfoils are higher, based on the rotor torque values, the wind turbine with asymmetrical airfoil blades NACA 0012 is better by 9.80% compared with NACA 4415 and 21.73% compared with NACA 63415. Self-starting issue can be addressed by proper selection of NACA blade profiles. By comparing the four airfoil blades in Part 1 and Part 2 of the papers, the asymmetrical NACA 0012 is found to be most suitable airfoil for self-starting the vertical axis wind turbine (VAWT).
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Chen, Jin, Jiang Tao Cheng, and Wen Zhong Shen. "Research on Design Methods and Aerodynamics Performance of CQU-DTU-B21 Airfoil." Advanced Materials Research 455-456 (January 2012): 1486–90. http://dx.doi.org/10.4028/www.scientific.net/amr.455-456.1486.
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This paper presents the design methods of CQU-DTU-B21 airfoil for wind turbine. Compared with the traditional method of inverse design, the new method is described directly by a compound objective function to balance several conflicting requirements for design wind turbine airfoils, which based on design theory of airfoil profiles, blade element momentum (BEM) theory and airfoil Self-Noise prediction model. And then an optimization model with the target of maximum power performance on a 2D airfoil and low noise emission of design ranges for angle of attack has been developed for designing CQU-DTU-B21 airfoil. To validate the optimization results, the comparison of the aerodynamics performance by XFOIL and wind tunnels test respectively at Re=3×106 is made between the CQU-DTU-B21 and DU93-W-210 which is widely used in wind turbines.
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Bostan, Viorel, Marin Guţu, and Valeriu Odainâi. "Aerodynamic efficiency enhancement for asymmetric profiles." MATEC Web of Conferences 178 (2018): 06022. http://dx.doi.org/10.1051/matecconf/201817806022.
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This paper presents a solution for enhancement of aerodynamic efficiency for asymmetric airfoils. In order to increase the lift and reduce the drag forces for a blade segment, a groove was created on its surface. There were carried out experiments consisting in the analysis of two asymmetric airfoil segments of the same type in the wind tunnel. One segment was designed with the groove and the other without it. The optimum location of the groove was determined by means of CFD analysis. Simulation results were compared to test results and the CFD analysis model was validated.
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Lee, H., and S. H. Kang. "Flow Characteristics of Transitional Boundary Layers on an Airfoil in Wakes." Journal of Fluids Engineering 122, no. 3 (February 14, 2000): 522–32. http://dx.doi.org/10.1115/1.1287592.
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Transition characteristics of a boundary layer on a NACA0012 airfoil are investigated by measuring unsteady velocity using hot wire anemometry. The airfoil is installed in the incoming wake generated by an airfoil aligned in tandem with zero angle of attack. Reynolds number based on the airfoil chord varies from 2.0×105 to 6.0×105; distance between two airfoils varies from 0.25 to 1.0 of the chord length. To measure skin friction coefficient identifying the transition onset and completion, an extended wall law is devised to accommodate transitional flows with pressure gradient and nonuniform inflows. Variations of the skin friction are quite similar to that of the flat plate boundary layer in the uniform turbulent inflow of high intensity. Measured velocity profiles are coincident with families generated by the modified wall law in the range up to y+=40. Turbulence intensity of the incoming wake shifts the onset location of transition upstream. The transitional region becomes longer as the airfoils approach one another and the Reynolds number increases. The mean velocity profile gradually varies from a laminar to logarithmic one during the transition. The maximum values of rms velocity fluctuations are located near y+=15-20. A strong positive skewness of velocity fluctuation is observed at the onset of transition and the overall rms level of velocity fluctuation reaches 3.0–3.5 in wall units. The database obtained will be useful in developing and evaluating turbulence models and computational schemes for transitional boundary layer. [S0098-2202(00)01603-5]
Dissertations / Theses on the topic "Airfoil profiles"
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Ahmed, Irfan [Verfasser]. "Development of Form-Adaptive Airfoil Profiles for Wind Turbine Application / Irfan Ahmed." Kassel : Kassel University Press, 2017. http://d-nb.info/1143155335/34.
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Allan, William D. E. "An experimental study of flow about an airfoil with slotted flap and spoiler using Joukowsky profiles." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28363.
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An experimental study has been carried out on an airfoil with slotted flap and spoiler using Joukowsky profiles. Pressure distributions
were measured as functions of angle of attack, flap deflection angle, spoiler size and inclination. The results are uncorrected for wind tunnel wall effects but the data base is available to carry out the corrections. The results will be used to compare with predictions of a theoretical model, yet to be worked out, which combines work previously done by Williams, Jandali, Parkinson and Yeung. This theory will involve the potential flow about a two-element 'near'-Joukowsky airfoil system. The secondary airfoil is a simulated slotted flap. Various size spoilers are introduced to the system at arbitrary angles of inclination using methods proposed by Parkinson and Yeung.
The experimental results are qualitatively reasonable and some interesting effects are observed. The behaviour of spoilers, when used with slotted flaps at various deflection angles, corresponds well with requirements of aircraft in approach or landing situations. Similarly, the use of slotted flaps alone provides the high lift at low angle of attack which is beneficial to aircraft taking off. Some recommendations are proposed for further testing with this equipment.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Lobato, Hugo Manuael Pinto. "An investigation into coordinate measuring machine task specific measurement uncertainty and automated conformance assessment of airfoil leading edge profiles." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3439/.
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The growing demand for ever more greener aero engines has led to ever more challenging designs and higher quality products. An investigation into Coordinate Measuring Machine measurement uncertainty using physical measurements and virtual simulations revealed that there were several factors that can affect the measurement uncertainty of a specific task. Measurement uncertainty can be affected by temperature, form error and measurement strategy as well as Coordinate Measuring Machine specification. Furthermore the sensitivity of circular features size and position varied, when applying different substitute geometry algorithms was demonstrated. The Least Squares Circle algorithm was found to be more stable when compared with the Maximum Inscribed Circle and the Minimum Circumscribed Circle. In all experiments it was found that the standard deviation when applying Least Squares Circle was of smaller magnitude but similar trends when compared with Maximum Inscribed Circle and the Minimum Circumscribed Circle. A Virtual Coordinate Measuring Machine was evaluated by simulating physical measurement scenarios of different artefacts and different features. The results revealed good correlation between physical measurements uncertainty results and the virtual simulations. A novel methodology for the automated assessment of leading edge airfoil profiles was developed by extracting the curvature of airfoil leading edge, and the method lead to a patent where undesirable features such as flats or rapid changes in curvature could be identified and sentenced. A software package named Blade Inspect was developed in conjunction with Aachen (Fraunhoufer) University for the automated assessment and integrated with a shop floor execution system in a pre-production facility. The software used a curvature tolerancing method to sentence the leading edge profiles which aimed at removing the subjectivity associated with the manual vision inspection method. Initial trials in the pre-production facility showed that the software could sentence 200 profiles in 5 minutes successfully. This resulted in a significant improvement over the current manual visual inspection method which required 3 hours to assess the same number of leading edge profiles.
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Junior, Joseph Youssif Saab. "Trailing-edge noise: development and application of a noise prediction tool for the assessment and design of wind turbine airfoils." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-14032017-140101/.
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This report concerns the research, design, implementation and application of an airfoil trailing-edge noise prediction tool in the development of new, quieter airfoil for large-size wind turbine application. The tool is aimed at enabling comparative acoustic performance assessment of airfoils during the early development cycle of new blades and rotors for wind turbine applications. The ultimate goal is to enable the development of quieter wind turbines by the Wind Energy Industry. The task was accomplished by developing software that is simultaneously suitable for comparative design, computationally efficient and user-friendly. The tool was integrated into a state-of-the-art wind turbine design and analysis code that may be downloaded from the web, in compiled or source code form, under general public licensing, at no charge. During the development, an extensive review of the existing airfoil trailing-edge noise prediction models was accomplished, and the semi-empirical BPM model was selected and modified to cope with generic airfoil geometry. The intrinsic accuracy of the original noise prediction model was evaluated as well as its sensitivity to the turbulence length scale parameter, with restrictions imposed accordingly. The criterion allowed comparison of performance of both CFD-RANS and a hybrid solver (XFLR5) on the calculation of the turbulent boundary layer data, with the eventual adjustment and selection of the latter. After all the elements for assembling the method had been selected and the code specified, a collaboration project was made effective between Poli-USP and TU-Berlin, which allowed the seamless coupling of the new airfoil TE noise module, \"PNoise\", to the popular wind turbine design/analysis integrated environment, \"QBlade\". After implementation, the code calculation routines were thoroughly verified and then used in the development of a family of \"silent profiles\" with good relative acoustic and aerodynamic performance. The sample airfoil development study closed the initial design cycle of the new tool and illustrated its ability to fulfill the originally intended purpose of enabling the design of new, quieter blades and rotors for the advancement of the Wind Energy Industry with limited environmental footprint.Este trabalho descreve a pesquisa de elementos iniciais, o projeto, a implantação e a aplicação de uma ferramenta de predição de ruído de bordo de fuga, no desenvolvimento de aerofólios mais silenciosos para turbinas eólicas de grande porte. O objetivo imediato da ferramenta é permitir a comparação de desempenho acústico relativo entre aerofólios no início do ciclo de projeto de novas pás e rotores de turbinas eólicas. O objetivo mais amplo é possibilitar o projeto de turbinas eólicas mais silenciosas, mas de desempenho aerodinâmico preservado, pela indústria da Energia Eólica. A consecução desses objetivos demandou o desenvolvimento de uma ferramenta que reunisse, simultaneamente, resolução comparativa, eficiência computacional e interface amigável, devido à natureza iterativa do projeto preliminar de um novo rotor. A ferramenta foi integrada a um ambiente avançado de projeto e análise de turbinas eólicas, de código aberto, que pode ser livremente baixado na Web. Durante a pesquisa foi realizada uma ampla revisão dos modelos existentes para predição de ruído de bordo de fuga, com a seleção do modelo semi-empírico BPM, que foi modificado para lidar com geometrias genéricas. A precisão intrínseca do modelo original foi avaliada, assim como sua sensibilidade ao parâmetro de escala de turbulência transversal, com restrições sendo impostas a esse parâmetro em decorrência da análise. Esse critério permitiu a comparação de resultados de cálculo provenientes de método CFD-RANS e de método híbrido (XFLR5) de solução da camada limite turbulenta, com a escolha do último. Após a seleção de todos os elementos do método e especificação do código, uma parceria foi estabelecida entre a Poli-USP e a TU-Berlin, que permitiu a adição de um novo módulo de ruído de bordo de fuga, denominado \"PNoise\", ao ambiente de projeto e análise integrado de turbinas eólicas \"QBlade\". Após a adição, as rotinas de cálculo foram criteriosamente verificadas e, em seguida, aplicadas ao desenvolvimento de aerofólios mais silenciosos, com bons resultados acústicos e aerodinâmicos relativos a uma geometria de referência. Esse desenvolvimento ilustrou a capacidade da ferramenta de cumprir a missão para a qual foi inicialmente projetada, qual seja, permitir à Indústria desenvolver pás mais silenciosas que irão colaborar com o avanço da energia eólica através da limitação do seu impacto ambiental.
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Olsson, Niklas, and Christian Selberg. "Numerical simulation and experimental validation of a manufactured wing profile." Thesis, Högskolan Väst, Avdelningen för Industriell ekonomi, Elektro- och Maskinteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-14287.
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The background for this thesis originates from a study of the flow characteristics for an airfoil of the type NACA0018. The aim for this thesis was to evaluate how the characteristics of the flow over the NACA0018 profile depend on surface roughness. Airfoils were manufactured in Aluminum by Computer Numerical Control-milling and in polylactide polymer using a 3D-printer, where some of the profile surfaces were postprocessed with sandpaper in various grain sizes. The surface roughness of the profiles was evaluated in a 3D optical profilometer using white light interferometry from Filmetrics. By that technique 3D surface plots were created. The manufactured airfoils were tested in a wind tunnel where the achieved data was made dimensionless for comparative purposes. The computational fluid dynamics simulations were performed in Ansys Fluent and compared against the wind tunnel data as well as with the data from a previously made study at htw saar. The results from the wind tunnel tests show that the surface roughness has an effect on the flow characteristic of the airfoil, where different angles of stall were observed in the comparison. The difference for the dimensionless numbers coefficient of lift and drag show that the manufactured aluminum airfoil performs better compared to the 3D-Printed airfoil in this study. It has a higher performance mean value for both of these coefficients in a span of angles between 0 and 30 degrees. When compared, the results from the simulations and wind tunnel experiments do match in some cases, where the dimensionless coefficients and stall angle coheres. Further studies based on this report are recommended, where small geometric changes to the profile could be tested and validated.
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Grim, Robert. "Aerodynamická optimalizace vysokovýkonného padákového kluzáku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241112.
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This thesis is focused on the aerodynamic analysis of the competition paraglider wing. Drags of the particular wing parts are divided into chapters. The aim was to get a grasp of sizes of the individual components drags in relation to the entire assembly. In the first instance, a 2D profile and then the entire configuration of the 3D wing was analyzed. After the evaluation, some power reserves were detected in an airfoil and so the airfoil shape was optimized. After the optimization of the individual components, the CFD calculation was used again. At the end, geometry changes were evaluated.
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Gulla, Duncan. "Ausgewählte statistische Betrachtungen im Flugzeugentwurf: Superkritische Profile und Fahrwerk." Aircraft Design and Systems Group (AERO), Department of Automotive and Aeronautical Engineering, Hamburg University of Applied Sciences, 2019. http://d-nb.info/1180601696.
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Kenntnisse über Parametereigenschaften und Charakteristiken von Flugzeugkomponenten sind eine wesentliche Grundlage für Methoden des Flugzeugentwurfs. Daher ist Ziel dieser Arbeit, statistische Merkmale und Kenngrößen einer für den Flugzeugbau und Entwurf relevanten Auswahl an Komponenten zu erschließen. Dabei wurden zunächst superkritische Tragflügelprofile hinsichtlich ihrer geometrischen Eigenschaften (relative Profildicke, Wölbung, Dickenrücklage, Wölbungsrücklage und der sogenannte "Leading Edge Sharpness Parameter") untersucht. Diese Eigenschaften wurden mit der Software XFLR5 aus einer Auswahl an superkritischen Profilgeometrien erhoben und mit grafischen und beschreibenden Statistikmethoden ausgewertet. Die Profile wiesen relative Wölbungen von 0 % bis 3,4 % auf, die Mehrzahl entfiel auf Wölbungen von 1 % bis 2 %. Die Wölbungsrücklagen zeigten die für superkritische Profile typische Lage im hinteren Profilbereich zwischen 70 % und 90 % der Profiltiefe. Die Dickenrücklagen verteilten sich um einen Mittelwert von 37 % der Profiltiefe. Eine Betrachtung von Flugzeugreifendimensionen sollte das Verhältnis von Reifenbreite zum Durchmesser w/d charakterisieren. Es wurde ein annähernd lineares Verhalten festgestellt. Die Werte des Parameters w/d umfassten einen Bereich von 0,3 bis 0,4. Durch Regressionsanalysen konnten auch die Abhängigkeiten des Parameters w/d von nur einer bekannten Reifendimension (Breite oder Durchmesser) aufgezeigt werden. Die im Rahmen dieser Arbeit dargestellten Erkenntnisse können als Grundlage weiterführender Untersuchungen genutzt werden.
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Yakhina, Gyuzel. "Experimental study of the tonal trailing-edge noise generated by low-reynolds number airfoils and comparison with numerical simulations." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC008/document.
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Le bruit tonal rayonné au bord de fuite des profils à faible nombre de Reynolds est un phénomène observé sur les ailes de drones ou micro-drones qui sont utilisés partout dans la vie quotidienne. La diminution de ce bruit va augmenter la survivabilité et l'efficacité des appareils dans le domaine militaire. De plus, cela va augmenter le champ des applications civiles et minimiser la pollution par le bruit. La réduction efficace du bruit est indispensable et, par conséquent, une compréhension complète du processus de rayonnement du bruit tonal du profil est nécessaire. Malgré le fait que des essais dédiés aient été réalisés depuis les années 70, il reste beaucoup de détails à expliquer. Le travail présenté est dédié à une étude expérimentale et analytique du bruit tonal. C'est une partie de collaboration entre l'Ecole Centrale de Lyon et Embry- Riddle Aeronautical University. Le but est de réaliser une caractérisation exhaustive des paramètres acoustiques et aérodynamiques du bruit tonal de bord de fuite d'un profil et de produire une base de données qui pourra être utilisée pour valider les simulations numériques réalisées dans le futur. Le profil symétrique NACA-0012 ainsi que le profil asymétrique SD7003 ont été testés pour une série d'angles d'incidence (de -10° à 10°) dans la soufflerie anéchoïque à jet ouvert de l'Ecole Centrale de Lyon pour des nombres de Reynolds modérés (0.6x105 < Rec < 2.6x105). Les mesures de pression aux parois et de pression acoustique en champ lointain pour différentes configurations ont permis d'observer une structure en escalier de la signature du bruit, de déterminer quelle face du profil a produit le bruit et de distinguer le rôle de la boucle de rétroaction. Des techniques supplémentaires de post-traitement comme l'analyse temps-fréquence ont montré l'existence de plusieurs régimes (un régime de commutation entre deux états, un régime d'une seul fréquence et un régime à plusieurs fréquences) de l'émission de bruit. L'analyse de bi-cohérence a montré qu'il y a des couplages nonlinéaires entre les fréquences. Une étude par l'anémométrie à fil chaud et par des techniques de visualisation de l'écoulement a montré que la formation d'une bulle de décollement est une condition nécessaire mais pas suffisante pour la génération du bruit. De plus, la localisation de la bulle est aussi importante et elle doit être suffisamment proche du bord de fuite. En outre, l'analyse de stabilité linéaire des résultats de simulations numériques a montré que des ondes de Tollmien-Schlichting sont transformées en ondes de Kelvin-Helmholtz dans la zone du décollement. Une prédiction analytique de l'amplitude des fréquences pures émises dans le champ lointain a été effectuée sur la base du modèle d'Amiet en supposant que le champ de pression pariétal est bidimensionnel. Les mesures de pression proches du bord de fuite du profil ont été prises comme données d'entrée. Les amplitudes prédites sont globalement en accord avec les mesures acoustiques. Après l'analyse de tous les résultats la description suivante du processus de rayonnement de sons purs peut être proposée. Les ondes de Tollmien-Schlichting qui se développent initialement dans la couche limite se transforment en ondes de Kelvin-Helmholtz le long de la couche de cisaillement de la bulle de décollement. Au bord de fuite du profil elles sont converties en ondes acoustiques qui forment un couplage fort avec les instabilités de couche limite plus en amont de l'écoulement, pilotant elles-mêmes le déclenchement de ces instabilitésThe tonal trailing-edge noise generated by transitional airfoils is a topic of interest because of its wide area of applications. One of them is the Unmanned Air Vehicles operated at low Reynolds numbers which are widely used in our everyday life and have a lot of perspectives in future. The tonal noise reduction will increase the survivability and effectiveness of the devices in military field. Moreover it will enlarge the range of civil use and minimize noise pollution. The effective noise reduction is needed and therefore the complete understanding of the tonal noise generation process is necessary. Despite the fact that investigation of the trailing-edge noise was started since the seventies there are still a lot of details which should be explained. The present work is dedicated to the experimental and analytical investigation of the tonal noise and is a part of the collaboration project between Ecole Centrale de Lyon and Embry-Riddle Aerospace University. The aim is to conduct an exhaustive experimental characterization of the acoustic and aerodynamic parameters of the trailing-edge noise and to produce a data base which can be used for further numerical simulations conducted at Embry-Riddle Aerospace University. A symmetric NACA-0012 airfoil and a slightly cambered SD7003 airfoil at moderate angles of attack (varied from -10° à 10°) were tested in an open-jet anechoic wind tunnel of Ecole Centrale de Lyon at moderate Reynolds numbers (0.6x105 < Rec < 2.6x105). Measurements of the wall pressure and far-field acoustic pressure in different configurations allowed to observe the ladder-type structure of the noise signature, to determine which side produced tones and to distinguish the role of the acoustic feedback loop. Additional post-processing techniques such as time-frequency analysis showed the existence of several regimes (switching regime between two tones, one-tone regime and multiple-tones regime) of noise emission. The bicoherence analysis showed that there are non-linear relationships between tones. The investigation of the role of the separation area by hot-wire anemometry and flow visualization techniques showed that the separation bubble is a necessary but not a suficient condition for the noise generation. Moreover the location of the bubble is also important and should be close enough to the trailing edge. Furthermore the linear stability analysis of accompanying numerical simulation results showed that the Tollmien-Schlichting waves transform to the Kelvin-Helmholtz waves at the separation area. An analytical prediction of the tone levels in the far-field was done using Amiet's model based on the assumption of perfectly correlated sources along the span. The wall-pressure measurements close to the trailing edge were used as an input data. The comparisons of the predicted levels and measured ones showed a good agreement. After analysis of all results the following description of the tonal noise mechanism is proposed. At some initial point of the airfoil the Tollmien-Schlichting instabilities start. They are traveling downstream and continued to Kelvin-Helmholtz waves along the shear-layer of the separation bubble. These waves reach the trailing edge, scatter from it as acoustic waves, which move upstream. The acoustic waves amplify the boundary layer instabilities at some frequencies for which the phases of both motions match and creates the feedback loop needed to sustain the process
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Krmela, Luděk. "Aerodyanmický návrh a výpočet kluzáku "Twin Shark"." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229321.
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The thesis contains determination of real aerodynamics characteristics of PW09-135 flap airfoil with help of calibration method via CFD, followed by accomplishment of CFD analysis of parts and the whole Twin Shark glider. Detailed research and optimization was made to flow field quality of fuselage and wing fuselage junction. On the basis of CFD solution was determine a stability control, static margin and angle of attack of a horizontal stabilizer. The thesis concludes an evaluation of results applicability in praxis.
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Dvořák, Petr. "Optimalizace štěrbinové vztlakové klapky letounu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228790.
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The main objective of this diploma thesis is to optimize the high lift device on the wing of the Phoenix Air U-15 ultralight aircraft, so that it complies with the UL-2 regulation regarding the stalling speed – 65 KPH. This is fulfilled by optimization of the slotted flap position. Methods used include the Response Surface Method and the Computational Fluid Dynamics approach – namely Ansys Fluent v6 software package. Furthermore, the paper deals with take-off flap optimization and construction of the flap deflection mechanism.
Books on the topic "Airfoil profiles"
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Lye, J. D. Recent developments in augmentor-wing aerofoil sections. [Downsview, Ont.]: De Havilland Aircraft Company of Canada, 1987.
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Bousman, William G. Airfoil dynamic stall and rotorcraft maneuverability. Moffett Field, Calif: National Aeronautics and Space Administration, Ames Research Center, 2000.
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Allison, Dennis O. Assessment of dual-point drag reduction for an executive-jet modified airfoil section. Hampton, Virginia: National Aeronautics and Space Administration, Langly Research Center, 1996.
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Hahne, David E. Full-scale semispan tests of a business-jet wing with a natural laminar flow airfoil. Hampton, Va: Langley Research Center, 1991.
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Scott, James R. Compressible flows with periodic vortical disturbances around lifting airfoils. [Cleveland, Ohio: Lewis Research Center, 1991.
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Johnson, William G. Pressure distributions from high Reynolds number tests of a Boeing BAC I airfoil in the Langley 0.3-Meter Transonic Cryogenic Tunnel. [Washington, D.C.]: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1985.
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Johnson, William G. Pressure distributions from high Reynolds number tests of a Boeing BAC I airfoil in the Langley 0.3-Meter Transonic Cryogenic Tunnel. [Washington, D.C.]: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1985.
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Applin, Zachary T. Pressure distributions from subsonic tests of a NACA 0012 semispan wing model. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1995.
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Applin, Zachary T. Pressure distributions from subsonic tests of a NACA 0012 semispan wing model. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1995.
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Shearin, John G. Acoustic effects on profile drag of a laminar flow airfoil. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1987.
Find full textBook chapters on the topic "Airfoil profiles"
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Khaimovich, I. N. "Computer-Aided Design of Die Tooling for Large Parts of Airfoil Profiles." In Proceedings of the 4th International Conference on Industrial Engineering, 1547–57. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-95630-5_165.
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Baeza, Antonio, Pep Mulet, and David Zorío. "High Order Extrapolation Techniques for WENO Finite-Difference Schemes Applied to NACA Airfoil Profiles." In Progress in Industrial Mathematics at ECMI 2016, 47–54. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-63082-3_6.
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Bahri, Harshit, Kaushalendra Kumar Singh, and Harvendra Singh. "CFD Study of Two-Dimensional Profile Geometry of an Airfoil." In Computational and Experimental Methods in Mechanical Engineering, 177–87. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-2857-3_19.
Full textConference papers on the topic "Airfoil profiles"
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Jiang, H. B., Y. R. Li, and Z. Q. Cheng. "Methods of Constructing Analytic Functions to Generate Airfoil Profiles." In 2015 International Conference on Electrical, Automation and Mechanical Engineering. Paris, France: Atlantis Press, 2015. http://dx.doi.org/10.2991/eame-15.2015.60.
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McGinley, Catherine, John Anders, and Frank Spaid. "Measurements of Reynolds stress profiles on a high-lift airfoil." In 16th AIAA Applied Aerodynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1998. http://dx.doi.org/10.2514/6.1998-2620.
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Bianchini, Alessandro, Francesco Balduzzi, Giovanni Ferrara, and Lorenzo Ferrari. "Aerodynamics of Darrieus Wind Turbines Airfoils During Start-Up." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57679.
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Recent studies have demonstrated that, when rotating around an axis orthogonal to the flow direction, airfoils are virtually transformed into equivalent airfoils with a camber line defined by their arc of rotation. In these conditions, the symmetric airfoils commonly used for Darrieus blades actually behaves like virtually cambered ones or, equivalently, rotors have to be manufactured with counter-cambered blades in order to have the performance of a symmetric airfoil. To complete these analyses, the present study focuses the attention on the airfoils’ aerodynamics during the start-up of the rotors. This phase of turbines’ functioning is indeed of particular interest since it actually defines the cut-in speed of the rotors and then notably impacts on the annual energy production, especially in case of small-size machines. In the work, unsteady CFD simulations have been carried out in start-up like conditions on three airfoils, i.e. a NACA 0018 and two modified profiles based on the same airfoil. The modified profiles have been conformally transformed to fit their camber lines to the arc of a circle, such that the ratio of the airfoil chord to the circle’s radius is 0.114 or 0.25. The study demonstrates that all the conventional theories based on one-dimensional aerodynamic coefficients (e.g. blade element momentum models) are affected by an intrinsic error in evaluating the starting torque profiles. Symmetric airfoils in fact exhibit a counter-intuitive non symmetric starting torque over the revolution. Conversely, airfoils compensated for the virtual camber effect show a substantially different starting torque profile, with a more symmetric distribution between the upwind and the downwind halves. This behavior is due to the effect of the pitching moment, which is usually neglected in lumped parameters models. At very low revolution speeds, its contribution becomes significant due to the very high angles of attack experienced by the blade. In particular, the pitching moment is non symmetric between the upwind and the downwind halves of the revolution. For upwind azimuthal positions the pitching moment reduces the overall torque output, while it changes sign in the downwind section, increasing the torque. The importance of accounting for the pitching moment contribution in low-order models (e.g. a blade element momentum model) is finally discussed by comparing the predicted torque profiles with those obtained by CFD.
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Sonoda, Toyotaka, and Heinz-Adolf Schreiber. "Aerodynamic Characteristics of Supercritical Outlet Guide Vanes at Low Reynolds Number Conditions." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90882.
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As a part of an innovative aerodynamic design concept for a single stage low pressure turbine, a high turning outlet guide vane is required to remove the swirl from the hot gas. The airfoil of the vane is a highly loaded compressor airfoil that has to operate at very low Reynolds numbers (Re ∼ 120,000). Recently published numerical design studies and experimental analysis on alternatively designed airfoils showed that blade profiles with an extreme front loaded pressure distribution are advantageous for low Reynolds number conditions. The advantage even holds true for an increased inlet Mach number at which the peak Mach number on the airfoils reaches and exceeds the critical conditions (Mss > 1.0). This paper discusses the effect of the inlet Mach number and Reynolds number on the cascade performance for both a controlled diffusion airfoil (CDA) (called baseline) and a numerically optimized front loaded airfoil. The results show that it is advantageous to design the profile with a fairly steep pressure gradient immediately at the front part in order to promote early transition or to prevent too large laminar — even shock induced — separations with the risk of a bubble burst. Profile Mach number distributions and wake traverse data are presented for design and off-design conditions. The discussion of Mach number distributions and boundary layer behavior is supported by numerical results obtained from the blade-to-blade flow solver MISES.
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Soltani, M. R., and M. Mahmoudi. "Experimental Investigation of Velocity Profiles in the Wake of an Oscillating Airfoil." In ASME/JSME 2007 5th Joint Fluids Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/fedsm2007-37440.
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A series of experiments were carried out to study the unsteady wakes behind an oscillating airfoil. The airfoil is a section of a wind turbine blade oscillating in pitch about the quarter chord axis at various reduced frequencies, oscillation amplitude and mean angles of attack. Real time velocity profiles were obtained using total and static pressure at 35 vertically aligned points behind the airfoil via two similar rakes. The rakes were located at a distance of 1.5 chord length behind the model. The results show great influence of oscillation amplitude and reduced frequency on the wake velocity profiles.
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Ilott, J., A. Asghar, W. D. E. Allan, and R. Woodason. "Further Investigation of the Influence of Real-World Blade Profile Variation on the Aerodynamic Performance of Transonic Nozzle Guide Vanes." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46558.
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This paper addresses the issue of aerodynamic consequences of variations in airfoil profile. An analysis of new and repaired airfoils was used to synthesize profiles representative of specific repair types. Five variations of a reference new low pressure turbine vane were obtained by changing the characteristic parameters of trailing-edge tweaking and laminate-repair methods used to refurbish turbine vanes. Flow visualization of shock structure and total pressure measurements were made by experimentation in a cascade rig and by calculations through Computational Fluid Dynamics (CFD). The performance of the modified profiles was compared with that of the reference new vane. The total pressure losses increased when the profile was bent at the trailing edge towards the pressure side. The losses for synthesized laminate repair profiles increased with an increase in the thickness of laminate repair. The numerical results were used to supplement experimental results in cases where the experimental conditions were not representative of typical design operating conditions.
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Edwards, R., A. Asghar, R. Woodason, M. LaViolette, K. Goni Boulama, and W. Allan. "Numerical Investigation of the Influence of Real World Blade Profile Variations on the Aerodynamic Performance of Transonic Nozzle Guide Vanes." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-23461.
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This paper addresses the issue of aerodynamic consequences of small variations in airfoil profile. A numerical comparison of flow field and cascade pressure losses for two representative repaired profiles and a reference new vane were made. Coordinates for the three airfoil profiles were obtained from the nozzle guide vanes of refurbished turboshaft engines using 3D optical scanning and digital modeling. The repaired profiles showed differences in geometry in comparison with the new vane, particularly near the leading and trailing edges. A numerical simulation was conducted using a commercial CFD code which uses the finite element approach for solving the governing equations. The computational predictions of the aerodynamic performance were validated with experimental results obtained from a transonic cascade consisting of blades with the same airfoil profiles. A CFD analysis was performed for the cascade at subsonic inlet and transonic exit conditions. Boundary layer growth, wake formation, and shock boundary layer interactions were observed in the two-dimensional computations. The flow field showed the presence of shock waves downstream of the passage throat and near the trailing edges of the blades. A conspicuous change in flow pattern due to subtle variation in airfoil profile was observed. The calculated flow field was compared with the flow pattern visualized in the experimental test rig using the Schlieren method. The total pressure calculation for the cascade exit showed an increase in pressure loss for one of the off-design profiles. The pressure loss calculations were also compared with the multi-hole total pressure probe measurement in the transonic cascade rig.
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Bianchini, Alessandro, Francesco Balduzzi, John M. Rainbird, Joaquim Peiro, J. Michael R. Graham, Giovanni Ferrara, and Lorenzo Ferrari. "An Experimental and Numerical Assessment of Airfoil Polars for Use in Darrieus Wind Turbines: Part 1 — Flow Curvature Effects." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42284.
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A better comprehension of the aerodynamic behavior of rotating airfoils in Darrieus Vertical-axis wind turbines (VAWTs) is crucial both for the further development of these machines and for improvement of conventional design tools based on zero or one-dimensional models (e.g. BEM models). When smaller rotors are designed with high chord-to-radius (c/R) ratios so as not to limit the blade Reynolds number, the performance of turbine blades has been suggested to be heavily impacted by a virtual camber effect imparted on the blades by the curvilinear flow they experience. To assess the impact of this virtual camber effect on blade and turbine performance, a standard NACA0018 airfoil and a NACA0018 conformally transformed such that the airfoil’s chord line follows the arc of a circle, where the ratio of the airfoil’s chord to the circle’s radius is 0.25 were considered. For both airfoils, wind tunnel tests were carried out to assess their aerodynamic lift and drag coefficients for Reynolds numbers of interest for Darrieus VAWTs. Unsteady CFD calculations have been then carried out to obtain curvilinear flow performance data for the same airfoils mounted on a Darrieus rotor with a c/R of 0.25. The blade incidence and lift and drag forces were extracted from the CFD output using a novel incidence angle deduction technique. According to virtual camber theory, the transformed airfoil in this curvilinear flow should be equivalent to the NACA0018 in rectilinear flow, while the NACA0018 should be equivalent to the inverted transformed airfoil in rectilinear flow. Comparisons were made between these airfoil pairings using the CFD output and the rectilinear performance data obtained from the wind tunnel tests and XFoil output in the form of pressure distributions and lift and drag polars. Blade torque coefficients and turbine power coefficient are also presented for the CFD VAWT using both blade profiles.
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Sadeghi, Hamed, and Mahmoud Mani. "Unsteady Flow Field in the Wake of an Airfoil." In ASME 2009 Fluids Engineering Division Summer Meeting. ASMEDC, 2009. http://dx.doi.org/10.1115/fedsm2009-78189.
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An experimental investigation was carried out to study the unsteady flow field behind a sinusoidally pitching airfoil at reduced frequencies 0.091, 0.182 and 0.273. Streamwise instantaneous velocity and streamwise mean velocity in the wake were measured by hot-wire anemometer at downstream distance from trailing edge of 0.25 chord. To assess the effect of mean incidence, data were taken at mean incidence angles of 0, 2.5 and 5 degrees. In all cases, the oscillation amplitude was set at 8 degree, and the Reynolds number, based on the chord length, was 50000. It is found that the mean incidence angle and reduced frequency have important influences on the instantaneous velocity profiles. As reduced frequency increases, more uniformity and stability in the wake are observed. When mean incidence angle is larger, more variations on thickness of profiles and velocity defect are found. Furthermore, mean velocity profiles and estimations of the momentum deficit coefficients are obtained. The results show that with increasing mean incidence, the velocity defect and momentum deficit increase. Instead, the higher reduced frequency decreases the momentum deficit and wake thickness.
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Alfayyadh, Ekhlas M., Sadeq H. Bakhy, and Yasir M. Shkara. "A New Multi-Objective Evolutionary Algorithm for Optimizing the Aerodynamic Design of HAWT Rotor." In ASME 2014 12th Biennial Conference on Engineering Systems Design and Analysis. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/esda2014-20355.
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This paper presents a new multi-objective evolutionary algorithm (MOEA) for optimum aerodynamic design of horizontal-axis wind turbines (HAWT). The design problem is set to find the blade shape such that optimizing multi-objective at different airfoil profiles. Combined Blade Element Momentum (BEM) theory and two different algorithms (Genetic (GA) and Enumeration) are used. Flow around subsonic airfoils is analyzed using XFOIL software. WINDMEL III wind turbine is selected to improve its aerodynamic performance with different airfoil profiles technique of National Renewable Energy Laboratory (NREL) family. Employing Genetic Algorithm embodied in Blade Element Momentum theory to calculate power, thrust and starting torque coefficients that are the fitness function. Another method, Enumeration method, is used to enhance evolutionary method results. The optimum solution acquired from combination of Genetic Algorithm and Blade Element Momentum theory of three blades configuration increased power coefficient by (25.8 %) and thrust coefficient by (16.6%). Enumeration method results increased power coefficient by (13.8%), while thrust coefficient decreased by (0.2%) from the original design. In general, the evolutionary method of combined GA and BEM theory with different airfoil profiles technique improved the turbine aerodynamic performance, and the results are in good agreement with other published papers.