1,180 research outputs found
Computational Study Of Diffuser Augmented Wind Turbine Using Actuator Disc Force Method
No full textIn this paper, a computational approach, based on the solution of Reynolds-averaged-Navier–Stokes (RANS) equations, to describe the flow within and around a diffuser augmented wind turbine (DAWT) is reported. In order to reduce the computational cost, the turbine is modeled as an actuator disc (AD) that imposes a resistance to the passage of the flow. The effect of the AD is modeled applying two body forces, upstream and downstream of the AD, such that they impose a desired pressure jump. Comparison with experiments carried out in similar conditions shows a good agreement suggesting that the adopted methodology is able to carefully reproduce real flow features
Multi-element ducts for ducted wind turbines: A numerical study
No full textMulti-element ducts are used to improve the aerodynamic performance of ducted wind turbines (DWTs). Steady-state, two-dimensional computational fluid dynamics (CFD) simulations are performed for a multi-element duct geometry consisting of a duct and a flap; the goal is to evaluate the effects on the aerodynamic performance of the radial gap length and the deflection angle of the flap. Solutions from inviscid and viscous flow calculations are compared. It is found that increasing the radial gap length results in an augmentation of the total thrust generated by the DWT, whereas a larger deflection angle has an opposite effect. Reasonable to good agreement is seen between the inviscid and viscous flow calculations, except for multi-element duct configurations characterized by large flap deflection angles. The viscous effects become stronger at large flap deflection angles, and the inviscid calculations are incapable of taking this phenomenon into account.</p
Ducted wind turbines: A potential energy shaper
No full textIn order to harvest wind resources more efficiently and to the greatest extent possible, unconventional wind turbine designs have been proposed, but never gained any acceptance in the marketplace. A team of researchers from TU Delft plans to revisit the concept of ducted wind turbines, which have been around for decades, and provide some clarity on its potential
Ducted wind turbines revisited: A computational study
No full textDucted Wind Turbines (DWTs) are one of the many concepts that have been proposed to improve the energy extraction from wind in comparison to bare wind turbines. In reviewing the DWT studies, investigations based on the combined use of theoretical, computational, and experimental techniques have been presented. Although indicated in these studies that the power output of wind turbines can be significantly increased by using surrounding ducts, the factors influencing this power increase, like the duct shape, augmentation add-on’s and yawed inflow conditions, need further investigation. These topics have been addressed in this doctoral thesis. The study presents a computational investigation of DWTs, employing two-dimensional and three-dimensional CFD simulations. To this intent, solutions obtained using panel, RANS, URANS and LB-VLES methods are shown. For reliable solution accuracy, verification and validation assessments are performed when possible. Through parametric investigation, it is found that the aerodynamic performance of the DWT can be improved by increasing the duct cross-section camber and a correct choice of turbine thrust force coefficient, whilst maintaining the same duct-exit-area ratio. The aerodynamic performance improvement for a DWT directly corresponds to the dimensionless duct thrust force coefficient. Flow analysis showed that flow separation when detected inside of the duct, reduces the duct thrust force coefficient and ultimately the aerodynamic performance of the DWT model. In an effort to further improve on the aerodynamic performance of the DWT, the effect of multi-element ducts and Gurney flap on the existing DWT models are investigated. The aerodynamic performance improvement with multi-element ducts strongly depends on the installation settings of the secondary duct element with respect to the primary DWT geometry. On the other hand, a Gurney flap retrofitted at the trailing edge of the duct improves the aerodynamic performance of the DWT model by delaying inner duct wall flow separation, thus increasing the mass flow rate at the turbine. Finally, the effects of yawed inflow condition on the aerodynamic and aeroacoustic performance of DWT models are studied in detail. The analysis showed that DWTs can demonstrate yaw insensitivity up to a specific yaw angle. The yaw insensitivity for the DWT model, however, strongly depends on the aerodynamic mutual interaction between the duct and turbine, which changes with the duct geometry, turbine configuration and yaw angle. While assessing the aeroacoustic performance of the DWT models, it is found that the DWT model xiii xiv Summary with highly cambered duct cross-section generates higher broadband noise levels, which results from the turbulent flow structures convecting along the surface of the duct.Wind Energ
Towards improving the aerodynamic performance of a ducted wind turbine: A numerical study
No full textThis paper aims to study the aerodynamic performance of ducted wind turbines (DWT) using inviscid and viscous flow calculations by accounting for the mutual interaction between the duct and the rotor. Two generalized duct cross section geometries are considered while the rotor is modelled as an actuator disc with constant thrust coefficient. The analysis shows the opportunity to significantly increase the overall aerodynamic performance of the DWT by a correct choice of the optimal rotor loading for a given duct geometry. Present results clearly indicate that the increased duct cross section camber leads to an improved performance for a DWT. Finally, some insights on the changes occurring to the performance coefficients are obtained through a detailed flow analysis
The 85th Anniversary of Academician V.V. Alekseev
No full textIn the article dedicated to the 85th anniversary of Doctor of Historical Sciences, Professor and Academician of the Russian Academy of Sciences Veniamin V. Alekseev, the author traces the main milestones of the scientific biography of the prominent historian who is a well-known specialist in the field of national history and the theory of historical process and the founder of the Institute of History and Archaeology of the Ural Branch of the Russian Academy of Sciences. The paper considers the main stages of the formation of the scientist, his scientific, organizational and administrative activities in the field of historical science. The author highlights the scientific results of Academician V.V. Alekseev that made him well known in Russia and abroad, his theoretical and methodological studies and such large blocks of scientific research as the history of Russian modernizations, the phenomenon of Russian regionalism, the history of metallurgy of the Urals and industrial heritage. The article also focuses on the features of the scientific method of V.V. Alekseev and his merits in the formation of the documentary base for historical research
The game space and its attributive characteristic in the novel "The defence" by V.V. Nabokov
No full text© Journal of Language and Literature. The article deals with the analysis of game space and its attributive characteristic in the novel "The Defence" by V.V. Nabokov. The author provides a review of the most interesting and significant works, devoted to the study of game phenomenon in the creative work by V.V. Nabokov. Besides, the meaning of notion "game text" is expanded in the work; there are also made the conclusions about lexical organization of the novel game space (it is a chessboard in this case) and about ways of characterization of this space: 1) direct characterization (through description); 2) indirect characterization (through the comparison with another subject)
The game space and its attributive characteristic in the novel "The defence" by V.V. Nabokov
No full text© Journal of Language and Literature. The article deals with the analysis of game space and its attributive characteristic in the novel "The Defence" by V.V. Nabokov. The author provides a review of the most interesting and significant works, devoted to the study of game phenomenon in the creative work by V.V. Nabokov. Besides, the meaning of notion "game text" is expanded in the work; there are also made the conclusions about lexical organization of the novel game space (it is a chessboard in this case) and about ways of characterization of this space: 1) direct characterization (through description); 2) indirect characterization (through the comparison with another subject)
Trips Of The Orientalist V.V. Barthold To Bukhara And Their Scientific Significance
No full textThis article discusses the trips of Academician V.V. Barthold to Bukhara to get acquainted with medieval monuments of writing, as well as scientific expeditions of Russian orientalists in the late 19th– early 20th centuries. The author analyzes the scientist's attitude to the issue of studying the history of Bukhar
Ground effect for ducted wind turbines: A computational study
No full textDucted wind turbines (DWTs) can take the advantage of ground effect (GE) when installed close to urban areas. To this aim, a parametric study to investigate the aerodynamic performance of DWTs in relation to three different ground distances are investigated. The flow around a commercial DWT model using a simplified duct actuator disc (AD) model based on Reynolds Averaged Navier-Stokes (RANS) equations is performed. The results indicate that DWTs placed close to the ground will lead to increased mass flow rate the turbine plane, and thereby improving the aerodynamic performance. However, the additional ground force leads to an asymmetric flow-field at the turbine plane, which will ultimately induce unsteady forces on the DWT system. The present analysis will serve as a strong recommendation to address siting issues for DWT manufacturers. Team Jan-Willem van Wingerde
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