Aerodynamic Design and Wind Tunnel Tests of Small-scale Horizontal-axis Wind Turbines for Low Tip Speed Ratio Applications

In recent times, the application of small-scale horizontal axis wind turbines (SHAWTs) has drawn interest in certain areas where the energy demand is minimal. These turbines, operating mostly at low Reynolds number (Re) and low tip speed ratio (λ) applications, can be used as stand-alone systems. The present study aims at the design, development, and testing of a series of SHAWT models. On the basis of aerodynamic characteristics, four SHAWT models viz., M1, M2, M3, and M4 composed of E216, SG6043, NACA63415, and NACA0012 airfoils, respectively have been developed. Initially, the rotors are designed through blade element momentum theory (BEMT), and their power coefficient have been evaluated. Thence, the developed rotors are tested in a low-speed wind tunnel to find their rotational frequency, power and power coefficient at design and off-design conditions. From BEMT analysis, M1 shows a maximum power coefficient (Cpmax) of 0.37 at λ = 2.5. The subsequent wind tunnel tests on M1, M2, M3, and M4 at 9 m/s show the Cpmax values to be 0.34, 0.30, 0.28, and 0.156, respectively. Thus, from the experiments, the M1 rotor is found to be favourable than the other three rotors, and its Cpmax value is found to be about 92% of BEMT prediction. Further, the effect of pitch angle (θp) on Cp of the model rotors is also examined, where M1 is found to produce a satisfactory performance within ±5° from the design pitch angle (θp, design).

Life Cycle Assessment of 2.0 MW Horizontal Axis Wind Turbine for Sustainability Analysis

The world is increasingly experiencing unanticipated catastrophic events because of the impact of greenhouse gasses. The two major issues with the conventional energy system are unsustainability and global warming, which are extremely harmful for the climate. The core objective of this study is a compilation of the findings related to a life cycle assessment of horizontal axis wind turbines in regard to sustainable development. Sustainability aspects and concerns have been studied and reported in terms of the life cycle of wind energy technology. This article focused on energy consumed during the life of the 2.0 MW wind turbine, mostly in the production of primary materials, processes, and maintenance-related transport phase. The turbine’s overall energy produced 1,750,000 kWh throughout a 20-year life. Over a 20year lifespan, the overall energy produced by the turbine is approximately 32% more than the energy needed to construct, and the destination for the turbine materials is a landfill at the end of the turbine’s life. For a 40% wind turbine power ratio, with the wind turbine materials delivered to landfill at the end of the turbine’s life, the electricity payback period is around 10 months, and for recycled materials it is 6 months. The comparison is also done for the wind turbine materials which are sent to landfill with and without recycling.

STATE OF THE ART OF SMALL WIND ENERGY ANALYSING DIFFERENT CONTROLS

There are two wind turbine topologies according to the axis of rotation: horizontal axis, "Horizontal Axis Wind Turbines" (HAWT) and vertical axis, "Vertical Axis Wind Turbines" (VAWT) [2]. HAWT turbines are used for high power generation as they have a higher energy conversion efficiency [2]. However, VAWTs are used in mini wind applications because they do not need to be oriented to the prevailing wind and have lower installation cost.

Wind power development in Eastern Kazakhstan threatens migration of eagles

On the basis of data obtained from ARGOS/GPS and GPS/GSM tracking of 34 eagles (4 Steppe Eagles (Aquila nipalensis) from Central KZ, 1 Steppe Eagle from Southern Ural region, 22 Steppe Eagles, 5 Eastern Imperial Eagles (Aquila heliaca) from the ASR and 2 Greater Spotted Eagles (Aquila clanga) from the from the Altai-Sayan Ecoregion), we have defined the main flyways, terms, and other parameters of migration of eagles through Eastern Kazakhstan. We have outlined the borders of the migration corridor and estimate the number of migrants passing through it. The study highlights the importance of the Karatau ridge for eagles from the vast territories of Russia and Kazakhstan. But we are also concerned about the development of wind farms with horizontal-axis wind turbines that expose ultimate danger for raptors in the Karatau migration corridor. One of them already exists – the Zhanatas Wind-Power Station. Here we calculated the possible negative impact on the eagle population from the existing and projected wind farms of the Karatau ridge and give our recommendations for neutralizing the damage from the development of the electric power industry in Karatau.

Vertical axis wind turbine operation in icing conditions: A review study

Vertical Axis Wind Turbine (VAWT) can be a promising solution for electricity production in remote ice prone territories of high north, where good wind resources are available, but icing is a challenge that can affect its optimum operation. A lot of research has been made to study the icing effects on the conventional horizontal axis wind turbines, but the literature about vertical axis wind turbines operating in icing conditions is still scarce, despite the importance of this topic. This paper presents a review study about existing knowledge of VAWT operation in icing condition. Focus has been made in better understanding of ice accretion physics along VAWT blades and methods to detect and mitigate icing effects.

Performance Enhancement of Horizontal Axis Wind Turbine Using Numerical Techniques

Wind turbines are one of the most prominent and popular sources of renewable energy, of which, horizontal axis wind turbines (HAWT) are the majorly chosen design for wind machines. These turbines rotate about the horizontal axis which is parallel to the ground. They comprise of aerodynamic blades (generated from the desired airfoil), that may be twisted or tapered as per the design requirements. The blades are attached to a rotor which is located either upwind or downwind. To help wind the orientation of the turbines, the upwind rotors have a tail vane, while the downwind rotors are coned which in turn help them to self-orient. One of the major reasons for the popularity of the horizontal wind turbine, is its ability to generate a larger amount of electricity for a given amount of wind. Due to its popularity, the enhancement in the design of HAWTs, is a major focus area for research. In the present study, a scaled-down CFD model of the NREL Phase VI was validated against the numerical and experimental data. The model used had a dual blade rotor and applied the S809 airfoil. The simulations were carried out using a rotating mesh in ANSYS Fluent. Validation was carried out for 3 velocities — 7m/s, 10m/s and 20m/s. Once validation was carried out, turbine was modified with the addition of vortex generators, in the form of cylindrical protrusions that reduce flow separation.

Wake Expansion and the Finite Blade Functions for Horizontal-Axis Wind Turbines

This paper considers the effect of wake expansion on the finite blade functions in blade element/momentum theory for horizontal-axis wind turbines. For any velocity component, the function is the ratio of the streamtube average to that at the blade elements. In most cases, the functions are set by the trailing vorticity only and Prandtl’s tip loss factor can be a reasonable approximation to the axial and circumferential functions at sufficiently high tip speed ratio. Nevertheless, important cases like coned or swept rotors or shrouded turbines involve more complex blade functions than provided by the tip loss factor or its recent modifications. Even in the presence of significant wake expansion, the functions derived from the exact solution for the flow due to constant pitch and radius helical vortices provide accurate estimates for the axial and circumferential blade functions. Modifying the vortex pitch in response to the expansion improves the accuracy of the latter. The modified functions are more accurate than the tip loss factor for the test cases at high tip speed ratio that are studied here. The radial velocity is important for expanding flow as it has the magnitude of the induced axial velocity near the edge of the rotor. It is shown that the resulting angle of the flow to the axial direction is small even with significant expansion, as long is the tip speed ratio is high. This means that blade element theory does not have account for the effective blade sweep due to the radial velocity. Further, the circumferential variation of the radial velocity is lower than of the other components.

Study and Design of a Horizontal Axis Wind Turbine (0.5 kW) Using Software Solid Works

In the present work, the study and design of a horizontal axis wind turbine suitable for the Cotonou site were investigated on the coast of Benin. A statistical study using the Weibull distribution was carried out on the hourly wind data measured at 10 m from the ground by the Agency for Air Navigation Safety in Africa and Madagascar (ASECNA) over the period from January 1981 to December 2014. Then, the models, techniques, tools and approaches used to design horizontal axis wind turbines were presented and the wind turbine components characteristics were determined. The numerical design and assembly of these components were carried out using SolidWorks software. The results revealed that the designed wind turbine has a power of 571W. It is equipped with a permanent magnet synchronous generator and has three aluminum blades with NACA 4412 biconvex asymmetrical profile. The values obtained for the optimum coefficient of lift and drag are estimated at 1.196 and 0.0189 respectively. The blades are characterised by an attack optimum angle estimated at 6° and the wedge angle at 5°. Their length is 2.50 m and the maximum thickness is estimated at 0.032 m for a rope length of 0.27 m. The wind turbine efficiency is 44%. The computer program designed on SolidWorks gives three-dimensional views of the geometrical shape of the wind turbine components and their assembly has allowed to visualize the compact shape of the wind turbine after export via its graphical interface. The energy quantity that can be obtained from the wind turbine was estimated at 2712,718 kWh/year. This wind turbine design study is the first of its kind for the study area. In order to reduce the technological dependence and the import of wind energy systems, the results of this study could be used to produce lower cost wind energy available on our study site.

New airfoils for micro horizontal-axis wind turbines

In this study, small horizontal-axis wind turbine blades operating at low wind speeds were optimized. An optimized blade design method based on blade element momentum (BEM) theory was used. The rotor radius of 0.2 m, 0.4 m and 0.6 m and blade geometry with single (W1 & W2) and multistage rotor (W3) was examined. MATLAB and XFoil programs were used to implement to BEM theory and devise a six novel airfoil (NAF-Series) suitable for application of small horizontal axis wind turbines at low Reynolds number. The experimental blades were developed using the 3D printing additive manufacturing technique. The new airfoils such as NAF3929, NAF4420, NAF4423, NAF4923, NAF4924, and NAF5024 were investigated using XFoil software at Reynolds numbers of 100,000. The investigation range included tip speed ratios from 3 to 10 and angle of attacks from 2° to 20°. These parameters were varied in MATLAB and XFoil software for optimization and investigation of the power coefficient, lift coefficient, drag coefficient and lift-to-drag ratio. The cut-in wind velocity of the single and multistage rotors was approximately 2.5 & 3 m/s respectively. The optimized tip speed ratio, axial displacement and angle of attack were 5.5, 0.08m & 6° respectively. The proposed NAF-Series airfoil blades exhibited higher aerodynamic performances and maximum output power than those with the base SG6043 and NACA4415 airfoil at low Reynolds number.