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Journal articles on the topic 'Betzův limit'

Author: Grafiati

Published: 4 June 2021

Last updated: 13 February 2022

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1

Freda, Robert, Bradford Knight, and Siddharth Pannir. "A Theory for Power Extraction from Passive Accelerators and Confined Flows." Energies 13, no. 18 (2020): 4854. http://dx.doi.org/10.3390/en13184854.

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No accepted fluid theory exists for power extraction from unpressurized confined flow. The absence of a valid model to determine baseline uniform power extraction in confined flows creates difficulties in characterizing the coefficient of power. Currently, the primary body of research has been limited to Diffuser Augmented Wind Turbines (DAWTs) and passive fluid accelerators. Fluid power is proportional to the cube of velocity; therefore, passive acceleration is a promising path to effective renewable energy. Hypothetical models and experiments for passive accelerators yield low ideal power li

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2

Allahverdyan, A. E., and E. A. Khalafyan. "Reexamination of Betz’s Limit for Wind Engines." Journal of Contemporary Physics (Armenian Academy of Sciences) 56, no. 1 (2021): 38–46. http://dx.doi.org/10.3103/s1068337221010047.

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3

Cuerva, A., and A. Sanz-Andrés. "The extended Betz–Lanchester limit." Renewable Energy 30, no. 5 (2005): 783–94. http://dx.doi.org/10.1016/j.renene.2004.07.017.

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4

van Kuik, Gijs A. M. "The Lanchester–Betz–Joukowsky limit." Wind Energy 10, no. 3 (2007): 289–91. http://dx.doi.org/10.1002/we.218.

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5

Farthing, S. P. "Betz Limit Not an Exact Optimum." Wind Engineering 37, no. 1 (2013): 105–9. http://dx.doi.org/10.1260/0309-524x.37.1.105.

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6

Vennell, Ross. "Exceeding the Betz limit with tidal turbines." Renewable Energy 55 (July 2013): 277–85. http://dx.doi.org/10.1016/j.renene.2012.12.016.

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7

De Lellis, Marcelo, Romeu Reginatto, Ramiro Saraiva, and Alexandre Trofino. "The Betz limit applied to Airborne Wind Energy." Renewable Energy 127 (November 2018): 32–40. http://dx.doi.org/10.1016/j.renene.2018.04.034.

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8

Okulov, V. "Limit cases for rotor theories with Betz optimization." Journal of Physics: Conference Series 524 (June 16, 2014): 012129. http://dx.doi.org/10.1088/1742-6596/524/1/012129.

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9

Chamorro, Leonardo P., and R. E. A Arndt. "Non-uniform velocity distribution effect on the Betz-Joukowsky limit." Wind Energy 16, no. 2 (2012): 279–82. http://dx.doi.org/10.1002/we.549.

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10

Loenbaek, Kenneth, Christian Bak, Jens I. Madsen, and Bjarke Dam. "Optimal relationship between power and design-driving loads for wind turbine rotors using 1-D models." Wind Energy Science 5, no. 1 (2020): 155–70. http://dx.doi.org/10.5194/wes-5-155-2020.

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Abstract. We investigate the optimal relationship between the aerodynamic power, thrust loading and size of a wind turbine rotor when its design is constrained by a static aerodynamic load. Based on 1-D axial momentum theory, the captured power P̃ for a uniformly loaded rotor can be expressed in terms of the rotor radius R and the rotor thrust coefficient CT. Common types of static design-driving load constraints (DDLCs), e.g., limits on the permissible root-bending moment or tip deflection, may be generalized into a form that also depends on CT and R. The developed model is based on simple re

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11

González-Hernández, José Genaro, and Rubén Salas-Cabrera. "Maximum Power Coefficient Analysis in Wind Energy Conversion Systems: Questioning, Findings, and New Perspective." Mathematical Problems in Engineering 2021 (July 19, 2021): 1–7. http://dx.doi.org/10.1155/2021/9932841.

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For decades, maximum power coefficient limit, known as the Betz limit, has been accepted as a theoretical optimum value for wind turbine power extraction; nevertheless, some reports, exceeding this limit, have already been published. To explain this phenomenon and show a different point of view, a novel theoretical and ideal analysis based on flow conservation law and areas’ quotient is presented, supported by a review of works related to surpassing the power coefficient limit approached from different perspectives.

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12

Gorban’, Alexander N., Alexander M. Gorlov, and Valentin M. Silantyev. "Limits of the Turbine Efficiency for Free Fluid Flow." Journal of Energy Resources Technology 123, no. 4 (2001): 311–17. http://dx.doi.org/10.1115/1.1414137.

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An accurate estimate of the theoretical power limit of turbines in free fluid flows is important because of growing interest in the development of wind power and zero-head water power resources. The latter includes the huge kinetic energy of ocean currents, tidal streams, and rivers without dams. Knowledge of turbine efficiency limits helps to optimize design of hydro and wind power farms. An explicitly solvable new mathematical model for estimating the maximum efficiency of turbines in a free (nonducted) fluid is presented. This result can be used for hydropower turbines where construction of

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13

Okulov, Valery L., and Jens N. Sørensen. "Refined Betz limit for rotors with a finite number of blades." Wind Energy 11, no. 4 (2008): 415–26. http://dx.doi.org/10.1002/we.274.

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14

OKA, Nobuhito, Yasushi KUROKAWA, Masato FURUKAWA, and Kazutoyo YAMADA. "1004 Toward Transcendence of the Theoretical Betz Limit Using Wind-Lens Turbine." Proceedings of the Fluids engineering conference 2014 (2014): _1004–1_—_1004–4_. http://dx.doi.org/10.1299/jsmefed.2014._1004-1_.

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15

Wood, D. H. "Generic Vortex Modelling for Horizontal-Axis Wind Turbines." Wind Engineering 26, no. 2 (2002): 71–84. http://dx.doi.org/10.1260/030952402761699269.

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This paper describes a generic free-wake calculation of wind turbine wakes. The expanding, helical, tip vortices are represented by a sequence of straight segments, the blades are modelled as lines of constant bound vorticity, and the hub vortices lie along the axis of rotation. It is shown that this model is consistent with the one-dimensional analysis that leads to the Lanchester-Betz limit, in that the velocity in the far-wake is uniform with radius. Particular attention is paid to turbines operating above the Lanchester-Betz limit. It is shown that the usual relationship between the veloci

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16

Wood, D. H. "Including Swirl in the Actuator Disk Analysis of Wind Turbines." Wind Engineering 31, no. 5 (2007): 317–23. http://dx.doi.org/10.1260/030952407783418766.

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It is shown that the presence of swirl in the wake of a wind turbine complicates the simple actuator disk analysis that provides such basic results as the Lanchester-Betz limit on the power coefficient. The simple analysis remains valid at high tip speed ratio for a sufficiently small core radius of the hub vortex. As the tip speed ratio decreases, the present analysis eventually becomes invalid. It is, however, reasonable to conclude that including the effects of the hub vortex causes the maximum power coefficient to increase above the Lanchester-Betz limit with decreasing tip speed ratio. Th

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17

Şen, Zekai. "Modified wind power formulation and its comparison with Betz limits." International Journal of Energy Research 37, no. 8 (2012): 959–63. http://dx.doi.org/10.1002/er.2900.

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18

West, Jacob R., and Sanjiva K. Lele. "Wind Turbine Performance in Very Large Wind Farms: Betz Analysis Revisited." Energies 13, no. 5 (2020): 1078. http://dx.doi.org/10.3390/en13051078.

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The theoretical limit for wind turbine performance, the so-called Betz limit, arises from an inviscid, irrotational analysis of the streamtube around an actuator disk. In a wind farm in the atmospheric boundary layer, the physics are considerably more complex, encompassing shear, turbulent transport, and wakes from other turbines. In this study, the mean flow streamtube around a wind turbine in a wind farm is investigated with large eddy simulations of a periodic array of actuator disks in half-channel flow at a range of turbine thrust coefficients. Momentum and mean kinetic energy budgets are

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19

Chattot, Jean-Jacques. "Optimization of Wind Turbines Using Helicoidal Vortex Model." Journal of Solar Energy Engineering 125, no. 4 (2003): 418–24. http://dx.doi.org/10.1115/1.1621675.

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The problem of the design of a wind turbine for maximum output is addressed from an aerodynamical point of view. It is shown that the optimum inviscid design, based on the Goldstein model, satisfies the minimum energy condition of Betz only in the limit of light loading. The more general equation governing the optimum is derived and an integral relation is obtained, stating that the optimum solution satisfies the minimum energy condition of Betz in the Trefftz plane “in the average.” The discretization of the problem is detailed, including the viscous correction based on the 2-D viscous profil

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20

Obretenov, Valentin, and Rossen Tliev. "A Study of a Darrieus Vertical Axis Wind Turbine with a guiding nozzle." E3S Web of Conferences 207 (2020): 02011. http://dx.doi.org/10.1051/e3sconf/202020702011.

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This paper presents the results from an experimental study of a Vertical Axis Wind turbine model with a guiding nozzle. The geometry of the nozzle is synthesized by an original methodology. The performance characteristics of the turbine are investigated when changing the number of the blades and their pitch angle. The obtained results allow us to generate generalized characteristics that can be used in the design of new turbines of this type. The results of the pilot studies showing higher efficiency than the classical Darrieus wind turbines (up to 50 % which is close to the Betz limit).

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21

Okulov, Valery L., and Gijs A. M. van Kuik. "The Betz-Joukowsky limit: on the contribution to rotor aerodynamics by the British, German and Russian scientific schools." Wind Energy 15, no. 2 (2011): 335–44. http://dx.doi.org/10.1002/we.464.

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22

Barbosa, D. L. M., D. A. T. D. R. Vaz, J. R. P. Vaz, et al. "A PROPOSED MATHEMATICAL MODEL FOR THE VELOCITY PROFILE INTERNALLY TO A CONICAL DIFFUSER." Revista de Engenharia Térmica 12, no. 2 (2013): 69. http://dx.doi.org/10.5380/reterm.v12i2.62050.

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The use of diffusers around of the horizontal-axis wind turbines have been widely studied, since the diffuser provides an improvement in the turbine power coefficient. These diffusers are often called Diffuser Augmented Wind Turbines (DAWT’s). The DAWT’s have the feature to make efficiency exceeding the Betz limit (maximum energy flow extracted = 59.26%), due to the increasing of the internal mass flow by influence of the diffuser presence. Thus, the present work proposed a mathematical model describing the behavior of the velocity profile internally to a diffuser according to the characterist

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23

Barbarić, Marina, and Zvonimir Guzović. "Investigation of the Possibilities to Improve Hydrodynamic Performances of Micro-Hydrokinetic Turbines." Energies 13, no. 17 (2020): 4560. http://dx.doi.org/10.3390/en13174560.

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Horizontal axis turbines are commonly used for harnessing renewable hydrokinetic energy, contained in marine and river currents. In order to encourage the expansion of electricity generation using micro-hydrokinetic turbines, several design improvements are investigated. Firstly, optimization-based design of rotor blade is used to get as close as possible to the efficiency limit of 59.3% (known as Betz limit), that counts for bare turbine rotors, placed in the free flow. Additional diffuser elements are further added to examine the potential to overcome the theoretical efficiency limit by acce

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24

Hsu, J. W. P. "Near-Field Scanning Optical Microscopy Studies of Materials and Devices." MRS Bulletin 22, no. 8 (1997): 27–30. http://dx.doi.org/10.1557/s0883769400033777.

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Near-field scanning optical microscopy (NSOM) provides a means to study optical and optoelectronic properties of materials at the nanometer scale. The key to achieving resolution higher than the diffraction limit is to place a subwavelength-sized light source—e.g., an aperture—within the near-field zone of the sample. In this case, the area of the sample illuminated is determined by the aperture size and not by the wavelength (see Figure 1). An image can then be formed by moving the sample and light source with respect to each other. While the principle of near-field optics is straightforward,

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25

Graf, U. U., R. Genzel, A. I. Harris, R. E. Hills, A. P. G. Russell, and J. Stutzki. "First Detection of 661 GHz 13CO J=6 →5: Large Amounts of Warm Molecular Gas." Symposium - International Astronomical Union 147 (1991): 424–26. http://dx.doi.org/10.1017/s0074180900199243.

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Submillimeter and far-infrared observations of carbon monoxide (Jaffe, Harris, and Genzel 1987; Genzel, Poglitsch, and Stacey 1988; Schmid-Burgk et al. 1989; Boreiko, Betz, and Zmuidzinas 1989) have indicated the presence of warm, dense molecular gas near regions of recent star forming activity. Estimates based on the comparison of mid-J (submm) and high-J (far-IR) 12CO lines in M17 and S106 (Harris et al. 1987a) gave a lower limit of ≈1018 cm−2 (τ(12CO 7 →6) ≈ 1) to the CO column density of quiescent (Δv ≤ 10 km/s) gas at temperatures of at least 100 K and H2 densities of 104 to 106 cm−3. The

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26

Graf, U. U., R. Genzel, A. I. Harris, R. E. Hills, A. P. G. Russell, and J. Stutzki. "First Detection of 661 GHz 13CO J=6 →5: Large Amounts of Warm Molecular Gas." Symposium - International Astronomical Union 147 (1991): 424–26. http://dx.doi.org/10.1017/s0074180900239867.

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Submillimeter and far-infrared observations of carbon monoxide (Jaffe, Harris, and Genzel 1987; Genzel, Poglitsch, and Stacey 1988; Schmid-Burgk et al. 1989; Boreiko, Betz, and Zmuidzinas 1989) have indicated the presence of warm, dense molecular gas near regions of recent star forming activity. Estimates based on the comparison of mid-J (submm) and high-J (far-IR) 12CO lines in M17 and S106 (Harris et al. 1987a) gave a lower limit of ≈1018 cm−2 (τ(12CO 7 →6) ≈ 1) to the CO column density of quiescent (Δv ≤ 10 km/s) gas at temperatures of at least 100 K and H2 densities of 104 to 106 cm−3. The

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27

Graham, J. M. R. "Rapid distortion of turbulence into an open turbine rotor." Journal of Fluid Mechanics 825 (July 24, 2017): 764–94. http://dx.doi.org/10.1017/jfm.2017.400.

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Rapid distortion of turbulence (RDT) theory is applied to homogeneous, isotropic turbulence incident on a horizontal axis turbine rotor such as a wind turbine or tidal-stream turbine. The mean flow field of the rotor which distorts the turbulence is represented by the commonly used axisymmetric actuator disc model due to Betz and Joukowski. The fluctuating streamwise component of the turbulence distorted by this field is calculated at the actuator disc plane. Turbulence velocity intensities and spectra are evaluated for general ratios of turbulence integral length scale to the rotor diameter,

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28

BARBOSA, DISTERFANO L. M., JERSON R. P. VAZ, SÁVIO W. O. FIGUEIREDO, MARCELO DE OLIVEIRA E. SILVA, ERB F. LINS, and ANDRÉ L. A. MESQUITA. "An Investigation of a Mathematical Model for the Internal Velocity Profile of Conical Diffusers Applied to DAWTs." Anais da Academia Brasileira de Ciências 87, no. 2 (2015): 1133–48. http://dx.doi.org/10.1590/0001-3765201520140114.

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The Diffuser Augmented Wind Turbines (DAWTs) have been widely studied, since the diffusers improve the power coefficient of the wind turbine, particularly of small systems. The diffuser is a device which has the function of causing an increase on the flow velocity through the wind rotor plane due to pressure drop downstream, therefore resulting in an increase of the rotor power coefficient. This technology aids the turbine to exceed the Betz limit, which states that the maximum kinetic energy extracted from the flow is 59.26%. Thus, the present study proposes a mathematical model describing th

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29

Bagheri-Sadeghi, Nojan, Brian T. Helenbrook, and Kenneth D. Visser. "Ducted wind turbine optimization and sensitivity to rotor position." Wind Energy Science 3, no. 1 (2018): 221–29. http://dx.doi.org/10.5194/wes-3-221-2018.

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Abstract. The design of a ducted wind turbine modeled using an actuator disc was studied using Reynolds-averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) simulations. The design variables included the rotor thrust coefficient, the angle of attack of the duct cross section, the radial gap between the rotor and the duct, and the axial location of the rotor in the duct. Two different power coefficients, the rotor power coefficient (based on the rotor swept area) and the total power coefficient (based on the exit area of the duct), were used as optimization objectives. The optimal v

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30

Sutikno, Priyono, Yuliandra Syahrial Nurdin, Doddy Risqi, Eki Mardani, and Erpinus Sihombing. "Experimental of Three Parallel Water Current Turbine with Optimized Straight Blades and Using Flow Concentrator Channeling Device to Augmented Performance and Self-Starting Capability." Applied Mechanics and Materials 758 (April 2015): 153–58. http://dx.doi.org/10.4028/www.scientific.net/amm.758.153.

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Water current turbine with vertical blade can be used on the river flow, ocean current or tidal current. The three parallel turbines with 40 degree azimuth different, have advantages doubling the power output and diminish the torque fluctuation. When the turbine equipped by the concentrator channeling device, the performance increased and the self-starting capability also augmented. During the experiments is indicated the flow phenomenon behind the turbine, the vortex formation created additional head or formation of low hydraulic level and facilitate the turbine coefficient of power produced

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31

Nishino, Takafumi, and Richard H. J. Willden. "The efficiency of an array of tidal turbines partially blocking a wide channel." Journal of Fluid Mechanics 708 (August 20, 2012): 596–606. http://dx.doi.org/10.1017/jfm.2012.349.

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AbstractA new theoretical model is proposed to explore the efficiency of a long array of tidal turbines partially blocking a wide channel cross-section. An idea of scale separation is introduced between the flow around each device (or turbine) and that around the entire array to assume that all device-scale flow events, including ‘far-wake’ mixing behind each device, take place much faster than the horizontal expansion of the flow around the entire array. This assumption makes it possible to model the flow as a combination of two quasi-inviscid problems of different scales, in both of which th

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32

Loth, J. L. "Aerodynamic Tower Shake Force Analysis for VAWT." Journal of Solar Energy Engineering 107, no. 1 (1985): 45–49. http://dx.doi.org/10.1115/1.3267652.

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Vertical axis wind turbines (VAWT) are subjected to blade lift forces which vary continuously in both magnitude and direction. These blade lift forces are transmitted via the blade support arms to the tower. The resulting tower force vector is a composite of: a downwind and a crosswind average force component, rotating force vectors, and force vectors oscillating in the crosswind direction. The frequency of the rotating and oscillating forces are multiples of the product of Bω, where B is the number of blades used and ω is the rotor angular velocity. The magnitude of the largest tower shake fo

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33

Hjort, Søren. "Non-Empirical BEM Corrections Relating to Angular and Axial Momentum Conservation." Energies 12, no. 2 (2019): 320. http://dx.doi.org/10.3390/en12020320.

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The Blade-Element Momentum (BEM) model for Horizontal-Axis Wind Turbines (HAWTs), although extremely useful, is known to be approximate due to model formulation insufficiencies, for which add-ons and corrections have been formulated over the past many decades. Scrutiny of the axial and azimuthal momentum conservation properties reveals momentum simplifications and absence of momentum sources not included in momentum theory underlying the standard BEM. One aspect relates to azimuthal momentum conservation, the wake swirl. This correction can be expressed analytically. Another aspect relates to

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34

WOOD, D. H., and J. BOERSMA. "On the motion of multiple helical vortices." Journal of Fluid Mechanics 447 (October 30, 2001): 149–71. http://dx.doi.org/10.1017/s002211200100578x.

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The analysis of the self-induced velocity of a single helical vortex (Boersma & Wood 1999) is extended to include equally spaced multiple vortices. This arrangement approximates the tip vortices in the far wake of multi-bladed wind turbines, propellers, or rotors in ascending, descending, or hovering flight. The problem is reduced to finding, from the Biot–Savart law, the additional velocity of a helix due to an identical helix displaced azimuthally. The resulting Biot–Savart integral is further reduced to a Mellin–Barnes integral representation which allows the asymptotic expansions to be

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35

Karsten, Richard, Amanda Swan, and Joel Culina. "Assessment of arrays of in-stream tidal turbines in the Bay of Fundy." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, no. 1985 (2013): 20120189. http://dx.doi.org/10.1098/rsta.2012.0189.

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Theories of in-stream turbines are adapted to analyse the potential electricity generation and impact of turbine arrays deployed in Minas Passage, Bay of Fundy. Linear momentum actuator disc theory (LMADT) is combined with a theory that calculates the flux through the passage to determine both the turbine power and the impact of rows of turbine fences. For realistically small blockage ratios, the theory predicts that extracting 2000–2500 MW of turbine power will result in a reduction in the flow of less than 5 per cent. The theory also suggests that there is little reason to tune the turbines

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36

Draper, S., T. Nishino, T. A. A. Adcock, and P. H. Taylor. "Performance of an ideal turbine in an inviscid shear flow." Journal of Fluid Mechanics 796 (April 28, 2016): 86–112. http://dx.doi.org/10.1017/jfm.2016.247.

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Although wind and tidal turbines operate in turbulent shear flow, most theoretical results concerning turbine performance, such as the well-known Betz limit, assume the upstream velocity profile is uniform. To improve on these existing results we extend the classical actuator disc model in this paper to investigate the performance of an ideal turbine in steady, inviscid shear flow. The model is developed on the assumption that there is negligible lateral interaction in the flow passing through the disc and that the actuator applies a uniform resistance across its area. With these assumptions,

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37

Meißner, Y., T. Rudi, R. Fischer-Betz, and A. Strangfeld. "AB0804 PREGNANCY AND PSORIATIC ARTHRITIS: A SYSTEMATIC LITERATURE REVIEW OF DISEASE ACTIVITY AND ADVERSE PREGNANCY OUTCOMES." Annals of the Rheumatic Diseases 79, Suppl 1 (2020): 1703–4. http://dx.doi.org/10.1136/annrheumdis-2020-eular.3076.

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Background:There is little robust evidence on the course of pregnancy and its outcomes in women with psoriatic arthritis (PsA) on which recommendations for the management of these patients could be based.Objectives:To review available data on disease activity during pregnancy and adverse pregnancy outcomes in women with PsA.Methods:Systematic literature search within the databases Pubmed and Embase using the keywords ‘psoriatic arthritis’ and ‘pregnan*/ obstetr*/ matern*/ gestation*/ deliver*/ abortion*/ reproduct*/ birth/ parity’. All full text articles published until 31 Dec 2019 were system

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Zbinden, A., K. Eriksson, and F. Förger. "AB1294-HPR LOW CONCENTRATIONS OF BIOLOGIC DMARDS IN BREASTMILK OF PATIENTS TREATED DURING LACTATION." Annals of the Rheumatic Diseases 79, Suppl 1 (2020): 1937.1–1937. http://dx.doi.org/10.1136/annrheumdis-2020-eular.4431.

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Background:There is very limited information about the passage of biologics into breast milk and into the peripheral blood of breastfed infants. However, based on pharmacological properties of biologic DMARDs (bDMARDs) lactation may not be discouraged in patients with chronic inflammatory rheumatic disease to treat or prevent postpartum relapses. We here report two cases treated with bDMARDs during lactation: one woman with Muckle-Wells syndrome (MWS) treated with canakinumab and one woman with microscopic polyangiitis (MPA) treated with rituximab.Objectives:To determine the level of rituximab

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39

Jamieson, Peter M. "Beating Betz: Energy Extraction Limits in a Constrained Flow Field." Journal of Solar Energy Engineering 131, no. 3 (2009). http://dx.doi.org/10.1115/1.3139143.

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Experiments with diffusers and other flow concentrating devices have shown that the power performance coefficient Cp of an energy extraction device, defined in relation to the area of flow intercepted at the device, may exceed the Betz limit. “Beating Betz,” in that sense, has been long established but no theory has existed to define in a generalized way what ideal limit may apply to Cp in such situations. Recent analysis has resolved this. This indicates that, irrespective of the presence of flow concentration systems or other influences that perturb the flow but do not in themselves extract

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40

Dabiri, John O. "Theoretical framework to surpass the Betz limit using unsteady fluid mechanics." Physical Review Fluids 5, no. 2 (2020). http://dx.doi.org/10.1103/physrevfluids.5.022501.

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41

Young, John, Fang-Bao Tian, Zhengliang Liu, Joseph C. S. Lai, Nima Nadim, and Anthony D. Lucey. "Analysis of unsteady flow effects on the Betz limit for flapping foil power generation." Journal of Fluid Mechanics 902 (September 14, 2020). http://dx.doi.org/10.1017/jfm.2020.612.

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42

Chattot, Jean-Jacques. "Actuator Disk Theory—Steady and Unsteady Models." Journal of Solar Energy Engineering 136, no. 3 (2014). http://dx.doi.org/10.1115/1.4026947.

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In this paper, the classical work on steady actuator disk theory is recalled and the interpretation of the flow as the continuous shedding of vortex rings of constant strength that causes the slip stream is shown to be consistent with the classical model, yet offers a different approach that provides more flexibility for the extension to unsteady flow. The ring model is in agreement with the conservation law theorems which indicate that the axial inductance inside the streamtube, far downstream, is twice that at the rotor disk. The actuator disk relationship between the power and the axial ind

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43

Venters, Ravon, Brian T. Helenbrook, and Kenneth D. Visser. "Ducted Wind Turbine Optimization." Journal of Solar Energy Engineering 140, no. 1 (2017). http://dx.doi.org/10.1115/1.4037741.

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This study presents a numerical optimization of a ducted wind turbine (DWT) to maximize power output. The cross section of the duct was an Eppler 423 airfoil, which is a cambered airfoil with a high lift coefficient (CL). The rotor was modeled as an actuator disk, and the Reynolds-averaged Navier–Stokes (RANS) k–ε model was used to simulate the flow. The optimization determined the optimal placement and angle for the duct relative to the rotor disk, as well as the optimal coefficient of thrust for the rotor. It was determined that the optimal coefficient of thrust is similar to an open rotor i

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44

Deam, R. T., E. Lemma, B. Mace, and R. Collins. "On Scaling Down Turbines to Millimeter Size." Journal of Engineering for Gas Turbines and Power 130, no. 5 (2008). http://dx.doi.org/10.1115/1.2938516.

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The purpose of this work is to establish the maximum theoretical efficiency that a viscous flow turbine (such as a Tesla turbine) can achieve. This is very much in the spirit of the Betz limit for wind turbines. The scaling down of viscous flow turbines is thought not to alter this result, whereas the scaling down of conventional turbines, whether axial or radial flow, results in an ever lowering of their efficiencies. A semiempirical scaling law is developed for conventional gas turbines using published machine performance data, which is fitted to a simple boundary layer model of turbine effi

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,, Mujiburrahman, and Heri Irawan. "ANALISIS PENGARUH SUDU TERHADAP UNJUK KERJA TURBIN ANGIN ATAP RUMAH PADA KECEPATAN ANGIN RENDAH MENGGUNAKAN SIMULASI CFD." AL-JAZARI JURNAL ILMIAH TEKNIK MESIN 3, no. 1 (2018). http://dx.doi.org/10.31602/al-jazari.v3i1.1393.

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Turbin angin yang di aplikasikan pada puncak kemiringan atap bentuk memanjang sangat jarang di aplikasikan di indonesia mengingat potensi angin kemiringan atap rumah yang tergolong kecepatan angin rendah dan cendrung ber ubah-ubah arah. Sehingga perlu dikembangkan turbin angin atap rumah yang mampu memaksimalkan angin rendah. (Watson et, 2008), melihat permasalahan tersebut tentunya pemilihan jenis turbin, bentuk airfoil, dan jumlah blade sangat menentukan prestasi turbin angin atap rumah. Selain itu pertimbangan aerodinamika bentuk airfoil yang diinginkan tentunya memiliki self starting yang

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Eneckdem, VadelTsopgni, Rodrigue Aimé Feumba, Odovie Tsomo, and Jean Roger Bogning. "Contribution of Cartography to the Optimization of the Evaluation of Wind Energy Potential in the Republic of Cameroon: Case of Bitchoua Highlands." Journal of Geography, Environment and Earth Science International, June 19, 2021, 53–66. http://dx.doi.org/10.9734/jgeesi/2021/v25i430284.

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This study deals with a model combining cartography with mathematical simulation for the optimal evaluation of wind potential in the context of the absence of networks of in-situ observation stations. It is based on both geographic Information Systems (GIS), climate data from NASA Surface Meteorology and Solar Energy (SSE) from 1985 to 2018, and field survey data from 2018.The NASA-SSE data, made it possible to obtain information on the direction of the winds, to determine parameters of distribution of wind speed frequencies (by the Weibull method).Then, we proceeded to the processing and nume

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