Investigation of effective parameters on darrieus wind turbine efficiency with aerodynamics models (original) (raw)
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Aerodynamic performance prediction of Darrieus-type wind turbines
INCAS BULLETIN, 2010
The prediction of Darrieus wind turbine aerodynamic performances provides the necessary design and operational data base related to the wind potential. In this sense it provides the type of turbine suitable to the area where it is to be installed. Two calculation methods are analyzed for a rotor with straight blades. The first one is a global method that allows an assessment of the turbine nominal power by a brief calculation. This method leads to an overestimation of performances. The second is the calculation method of the gust factor and momentum which deals with the pale as being composed of different elements that don't influence each other. This method, developed based on the theory of the turbine blades, leads to values close to the statistical data obtained experimentally. The values obtained by the calculation method of gust factor-momentum led to the concept of a Darrieus turbine, which will be tested for different wind values in the INCAS subsonic wind tunnel.
Study on the analysis method for the vertical-axis wind turbines having Darrieus blades
Renewable Energy, 2013
Recent interest in Darrieus wind turbines has led to a need for proper performance prediction models. Of all the existing models, multiple streamtubes model is reasonably simple and relatively precise. However, neglecting dependency of Reynolds number (Re) leads to the failure of prediction at high tip-speed ratios (TSR). In this proposed paper, an algorithm LDWT, which applied local blade Re instead of one representative Re, was developed and researched. In the calculation, 2-dimensional experimental data for aerofoil characteristics were applied because their 3-dimensional data for different Re could not be accessible. This study shows that results for high TSR from LDWT match test data better than previous research instead of underestimation in other regions. In the region of low TSR, it is shown that stall delay model is needed to match well with test data. Therefore, it is expected to be useful in the proper design and optimisation of rotors at high tip-speed ratios when their test data is not available or incomplete.
Numerical Simulation on Aerodynamic Performance of a Three-Bladed Darrieus – H Wind Turbine 1
2016
The purpose of this research work is to investigate computationally the improvement of the performance of the vertical-axis Darrieus-H wind turbine.The simulations of the aerodynamic field around a four-bladed straight –axis wind turbine (VAWT) are presented for different values of the Tip Speed Ratio λ (TSR), λ = 1.5 to λ = 3. Six different pitch angles are considered with symmetrical airfoil NACA0015. The Reynolds-Averaged Navier–Stokes equations are completed by the Kώ SST turbulence model. Multiple Reference Frames (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 speed. The results show that the optimized turbine experienced maximum power coefficient of 0.41 in tip speed ratio of 2.5 and in pitch angle 6° for CFD simulations. The experimental data from the literature and computational results were then compare...
The Darrieus wind turbine: Proposal for a new performance prediction model based on CFD
Energy, 2011
This paper presents a CFD model for the evaluation of energy performance and aerodynamic forces acting on a straight-bladed vertical-axis Darrieus wind turbine. The basic principles which are currently applied to BE-M theory for rotor performance prediction are transferred to the CFD code, allowing the correlation between flow geometric characteristics (such as blade angles of attack) and dynamic quantities (such as rotor torque and blade tangential and normal forces). The model is proposed as a powerful design and optimization tool for the development of new rotor architectures for which test data is not available. After describing and validating the computational model against experimental data, a full campaign of simulation is proposed for a classical NACA 0021 three-bladed rotor. Flow field characteristics are investigated for several values of tip speed ratio, allowing a comparison among rotor operation at optimum and lower C p values, so that a better understanding of vertical-axis wind turbines basic physics is obtained.
Sustainability
The use of wind energy can be traced back thousands of years to many ancient times. Among the tools used for converting wind energy was the vertical-axis wind turbine (vawt). Investigating the performance of this type of turbine is an interesting topic for researchers. The appropriate correlation between the Double Multiple Stream Tube (DMST) model and the experimental results has led researchers to pay distinct attention to this model for vawt simulation. In this study, using the aforementioned model, the appropriate range of important wind turbine design parameters was determined. First, the model outcome was validated based on experimental results and then, the performances of 144 different turbine types were simulated with respect to chord length, number of blades, H/D ratio and airfoil type. Chord length was evaluated at three levels, 0.1, 0.15 and 0.2 m, number of blades 2, 3 and 4, Height to Diameters (H/D) ratio of 0.5, 1, 1.5 and 2, and four types of airfoils, NACA0012, NAC...
European Journal of Technic, 2019
Wind energy is among the most cost-effective renewable energies. Till date, turbines with different configurations had been designed to harness wind power, each having unique superiorities. Darrieus turbines are one of the mostly investigated vertical axis wind turbines using either experimental or numerical methods. Experimental analyses are time consuming works which requires high amount of effort and expenses. Thus, computational fluid dynamics (CFD) methods have been commonly used by scientists and engineers in order of obtaining detailed performance and illustration of the fluid flow. Contrary to the horizontal axis machines, Darrieus turbines are difficult to be analyzed by CFD algorithms due to high pressure and velocity variations which arise from extreme changes in the angle of attack beyond the stall condition at different azimuthal position of the blades. Therefore, more simplified numerical models are generated employing double multiple streamtube (DMS) theory together with additional improvements. QBlade is one of the mostly used numerical methods based on the lifting line free vortex wake method developed for calculating rotor aerodynamics. The main scope of this study is to design a straight bladed Darrieus turbine (D=1028 mm, H=1460 mm, N=3) and to verify the double multiple streamtube theory and QBlade algorithm with the experimental and computational works. Analysis results represented good agreement with the previous studies especially at lower TSR ranges. Compare to the experimental results, an overestimation in the power coefficient is obtained at low free stream speed and high TSR ranges after exceeding the peak point. Sensitivity of the model to the Re number variations have also been outlined.
Bitlis Eren Üniversitesi Fen Bilimleri Dergisi, 2020
Increasing energy demand, rising per capita energy use, growing climate problems and other detrimental consequences of energy and environmental issues have prompted scientists and engineers to conduct more studies on the technical feasibility and efficiency of renewable energy conversion systems. Free flow (wind and hydrokinetic) turbines are one of the mostly investigated renewable energy technologies and Darrieus turbines have an exceptional place especially for smaller scale and domestic applications. Many experimental and computational studies have been provided on the performance of Darrieus turbines. However, the number of numerical studies which are more time and cost effective than computational and experimental works are quite limited in the literature. The main objective of this study is to analyze Darrieus turbines at different geometrical and dynamic configurations using numerical QBlade software. In this study, the effect of airfoil selection, number of blades, chord length, solidity and helicity are analyzed in terms of delivering higher performance at straight bladed Darrieus turbines. It has been found that NACA 0020 profile performs better relative to other symmetrical blade sections in vertical axis turbines. Better performance and wider TSR range is obtained for three bladed turbines. Also, increasing chord lengths delivered maximum power at lower tip speed ratio (TSR) ranges. This study is expected contribute site-dependent Darrieus turbine design works at different dimension and dynamic scales for both wind and hydrokinetic applications.
2019
This paper presents a model for the evaluation of the optimal design of Darrieus vertical axis wind turbine by CFD analysis and experimental tests, through analyzing six models of Darrieus wind turbines, number of blades and tip speed ratio. For this purpose, a full investigation campaign has been carried out through a systematic comparison of numerical simulations with wind tunnel experiments data. The airfoil profile used in the turbine blades was DU06W200 and constant geometry dimensions to turbines. The experiments were done for all Darrieus wind turbine models by using a subsonic wind tunnel under open type test section with airflow speed range (3-7.65) m/s and different tip speed ratio TSR. The results show that Darrieus WT straight type can be self-starting at the wind velocity 3 m/s, where other types cannot be starting at less than wind speed 5 m/s. The rotational speed (N) increases for all models with the wind velocity increase. The power coefficient (CP) increases when t...
On the aerodynamics of variable-geometry oval-trajectory Darrieuswind turbines
2007
A new computational model for the aerodynamics of vertical-axis wind turbines is introduced. It is based on the double-multiple streamtube concept and it incorporates the capacity of dealing with rotors whose blades follow oval-trajectories at variable setting-angles. We applied this model to the study of the aerodynamics of an innovative concept in extra-large wind-power plants: the VGOT (variable-geometry oval-trajectory) Darrieus wind turbine. Due to the especial geometric characteristics of the VGOT Darrieus, it was necessary to propose three new non-dimensional parameters to quantify its performance under different wind-conditions: the equivalent power coefficient, the equivalent solidity coefficient and the trajectory efficiency. We show some numerical results testing several rotor configurations working under different wind scenarios. r