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Wind Tunnel Experiments and Numerical Study on Performance Characteristics of an H-type Vertical Axis Wind Turbine in the Spanwise Direction

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Journal of Thermal Science 2021年第3期30卷 758-771页

作者： ZHANG Yanfeng LI Qing’an ZHU Xinyu SONG Xiaowen CAI Chang GUO Zhiping College of Science Inner Mongolia University of TechnologyHohhot 010051China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China College of Mechanical Engineering Inner Mongolia University of TechnologyHohhot 010051China

The aerodynamic forces and vortex characteristics of an H-type Vertical Axis Wind Turbine(VAWT)become complicated because of dynamic stall,particularly in the three-dimensional impact on the blade spanwise *** study focused on the evaluation of the aerodynamic performance and vortex characteristics of an H-type VAWT in the spanwise direction by numerical simulations and wind tunnel *** acting on the blade surface was obtained from multiport pressure measurement devices by wind ***,the vortex field around different blade sections was investigated through numerical *** stall behavior was analysed by comparing the results of numerical simulations and *** a result,the tangential force of single blade was mainly contributed at the chordwise position of x/c≤0.4 c and the power of single blade was mainly contributed at the azimuthal angle range of 60°≤θ≤150°in the blade section position region of 0≤z/(H/2)≤*** the section position of z/(H/2)=0.5,the initial flow separation was found at the suction side and progressed forward to the leading *** the increase of the tip speed ratios,the decreasing position of the averaged local power coefficient of each section was closer to the middle section of z/(H/2)=0,and the attenuation speed became *** power coefficient reductions at the blade section position of z/(H/2)=0.9 were 38.29%,46.78%and 56.42%when the tip speed ratios were 1.38,2.19 and 2.58,*** results of this study provided a better understanding of the development of the performance characteristics and vortex characteristics of H-type VAWT.

关键词： VAWT wind tunnel experiments CFD spanwise direction pressure distribution power coefficient

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Theoretical and Empirical Limits: Reexamining Betz’s Upper Limit towards a Practical power coefficients in Wind Turbines*

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World Journal of Engineering and Technology 2024年第4期12卷 851-866页

作者： Richard M. Kimiti Francis N. Kariuki Joseph N. Kamau Timonah N. Soitah Department of Physics JKUAT University Nairobi Kenya

The aspiration of all wind turbine designers is to attain Betz’s upper limit, which represents the highest efficiency in wind energy extraction. Majority of working turbines operate slightly below this limit with an exception of a few operating in wind tunnels. This study proposes for a comprehensive reevaluation of Betz’s derivation, aiming to establish the gap between a theoretical power limit and a practical limit for realization. There are two common expressions for power coefficient giving the same optimal value of 59%, but they generate different power-coefficient curves when plotted against velocity ratios. This paper presents a new method being referred as “Direct Multiplication Fractional Change” (DMFC) for deriving power-coefficient curves in wind energy, and compares its generated curve with established models. Discrepancies in power-coefficient expressions are identified and harmonized. Three approaches, namely EVAM, LVM, and DMFCM, were used for the numerical derivation of cp in the study, with their evaluation summarized in a table. The study collaborates its findings with a formulated velocity-distance curve, commonly presented as a hypothetical velocity profile in some publications. The results from DMFCM indicate two distinct maxima for the power coefficient. On the front side of the disc, a maximum of 0.5 is achievable in practice, although it is not the highest theoretically. On the rear side, a theoretical maximum of 0.59 is observed, but this value is not attainable in practice. These maxima are separated by their positions along the line of flow relative to the disc. However, this approximation is limited to a streamlined flow model of the rotor disc.

关键词： Wind Turbine Betz’s Limit power coefficient Kinetic Pressure Rotor Disc

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Numerical investigation on the flow and power of small-sized multi-bladed straight Darrieus wind turbine

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第9期8卷 1414-1421页

作者： JIANG Zhi-chao DOI Yasuaki ZHANG Shu-you College of Mechanical and Energy Engineering Zhejiang University Hangzhou 310027 China Hangshen Holding Group Co.. Ltd Hangzhou 311234 China Graduate School of Engineering. Hiroshima UniversiO＇ Higashi-hiroshima Hiroshima 739-852 7 Japan

Straight Darrieus wind turbine has attractive characteristics such as the ability to accept wind from random direction and easy installation and maintenance. But its aerodynamic performance is very complicated,especially for the existence of dynamic stall. How to get better aerodynamic performance arouses lots of interests in the design procedure of a straight Darrieus wind turbine. In this paper,mainly the effects of number of blades and tip speed ratio are discussed. Based on the numerical investigation,an assumed asymmetric straight Darrieus wind turbine is proposed to improve the averaged power coefficient. As to the numerical method,the flow around the turbine is simulated by solving the 2D unsteady Navier-Stokes equation combined with continuous equation. The time marching method on a body-fitted coordinate system based on MAC (Marker-and-Cell) method is used. O-type grid is generated for the whole calculation domain. The characteristics of tangential and normal force are discussed related with dynamic stall of the blade. Averaged power coefficient per period of rotating is calculated to evaluate the eligibility of the turbine.

关键词： Small-sized Straight Darrieus wind turbine Multi-bladed power coefficient

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Criterion of aerodynamic performance of large-scale offshore horizontal axis wind turbines

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Applied Mathematics and Mechanics(English Edition) 2010年第1期31卷 13-20页

作者：程兆雪李仁年杨从新胡文瑞 Lanzhou University of Technology Institute of Mechanics Chinese Academy of Sciences

With the background of offshore wind energy projects, this paper studies aerodynamic performance and geometric characteristics of large capacity wind turbine rotors （1 to 10 MW）, and the main characteristic parameters such as the rated wind speed, blade tip speed, and rotor solidity. We show that the essential criterion of a high- performance wind turbine is a highest possible annual usable energy pattern factor and a smallest possible dimension, capturing the maximum wind energy and producing the maximum annual power. The influence of the above-mentioned three parameters on the pattern factor and rotor geometry of wind turbine operated in China＇s offshore meteoro- logical environment is investigated. The variation patterns of aerodynamic and geometric parameters are obtained, analyzed, and compared with each other. The present method for aerodynamic analysis and its results can form a basis for evaluating aerodynamic performance of large-scale offshore wind turbine rotors.

关键词： offshore wind energy project horizontal axis wind turbine rotor aerody-namic design annual usable energy pattern factor power coefficient wind turbine rotor,wind turbine blade

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Experimental study on the optimum design of diffuser-augmented horizontal-axis tidal turbine

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Clean Energy 2022年第5期6卷 776-786页

作者： Evi Elisa Ambarita Harinaldi Rifqi Azhari Ridho Irwansyah Department of Mechanical Engineering Universitas IndonesiaKampus UI Depok 16424Indonesia

Ocean current energy is a promising and reliable resource that offers sustainability and predictability in realizing green future needs.A diffuser-augmented horizontal-axis turbine is utilized to generate ocean current energy.A numerical study on the impact of diffuser angle variations on the power coefficient has been carried out in the previous *** elucidate the fluid dynamics aspects and further validation of previous computational results,the experimental investigation on the optimal design of tidal turbine with 20.04°diffuser augmentation is presented in this *** study was conducted in a flowing tank with a current velocity of 0.7 m/*** maximum power coefficient of 20.04°is 0.436 experimentally,which is a little smaller than the numerical ***,to reinforce the 20.04°result,a diffuser with an angle of 10.43°was also manufactured and tested *** maximum power coefficient of 10.43°is 0.303 experimentally,which is 3%smaller than the numerical *** was concluded that the numerical approach might be considered satisfactory and represent similar phenomena to the experimental investigation in an application for modelling of multi-objective optimization.

关键词： ocean current energy tidal turbine diffuser augmentation power coefficient experimental study

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Determination of Vertical Axis Wind Turbines Optimal Configuration through CFD Simulations

Determination of Vertical Axis Wind Turbines Optimal Configu...

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2012 International Conference on Future Environment and Energy（ICFEE 2012）

作者： Payam Sabaeifard Haniyeh Razzaghi Ayat Forouzandeh Young Researchers Club Islamic Azad University Tehran Central branch Tehran Iran

Using vertical axis wind turbines at buildings seems favorable due to the fact that they do not suffer from frequent wind direction changes,have a design simply integrate with building architecture and they have better response in turbulence wind flow which is common in urban *** paper presents a computational and experimental study into the aerodynamics and performance of small scale Darrieus-type straight-bladed vertical axis wind turbines and describes the effect of some design parameters including number of blades,airfoil type and turbine solidity on the performance of them.K-ε turbulence model is chosen to perform the transient simulations and multiple reference frame（MRF） model capability of a computational fluid dynamics （CFD） solver is used to express the dimensionless form of power output of the wind turbine as a function of the wind freestream velocity and the rotor’s rotational *** results show that the optimized turbine experienced maximum power coefficient of 0.36 and 0.32 in tip speed ratio of 3.5 for CFD simulations and wind tunnel test respectively.

关键词： Wind Energy Vertical Axis Wind Turbine Computational Fluid Dynamics power coefficient

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