Small-scale Wind Turbine Blade Research Articles

Optimal airfoil selection for small horizontal axis wind turbine blades: A multi-criteria approach

Over the last century, the growing demand for clean energy has emphasized wind energy as a promising solu-tion to address contemporary energy challenges. Within the realm of wind energy, the wind turbine plays a pivotal role in harnessing the kinetic energy of the wind and converting it into electrical power. Among the various components of the wind turbine system, turbine blades assume a critical role in capturing the wind's kinetic energy and converting it into rotational motion. Consequently, the design of wind turbine blades holds the utmost importance in determining the overall performance and efficiency of the entire wind turbine system. One essential aspect of blade design involves selecting an appropriate airfoil. Throughout history, numerous airfoil profiles have been developed for various applications. Notably, National Advisory Committee for Aeronautics (NACA) and National Renewable Energy Laboratory (NREL) airfoils have been tailored for aircraft and large-scale wind turbine blades, respectively. However, the quest for suitable airfoil types for small-scale wind turbine blades has been ongoing. This study delves into an examination of over 62 distinct NACA and NREL aerofoil types tailored for small horizontal-axis wind turbine blades. Employing specialized software, namely QBlade, specifically designed for modeling and simulating wind turbine blades, the study calculates key parameters such as power output, stress, deformation, and weight for each airfoil. Subsequently, based on the simulated data, the optimal airfoil is identified using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) multi-criteria selection approach. This selection process takes into account simulation results pertaining to power output, stress, deformation, and weight. The decision-making process involving multiple criteria is facilitated using Excel and Python. The findings of this study reveal that among the 62 airfoil types under consideration, the NACA 0024, NACA 2424, and NACA 4424 airfoils emerge as the most suitable choices for small horizontal-axis wind turbine blades.

Aerodynamic design and optimization of a small-scale wind turbine blade using a novel artificial bee colony algorithm based on blade element momentum (ABC-BEM) theory

In this study, a novel optimization technique called the Artificial Bee Colony Algorithm based on Blade Element Momentum Theory (ABC-BEM) was developed and applied for the first time to design a small-scale wind turbine blade. Using the ABC-BEM, the aerodynamic geometry of a 1 kW small-scale wind turbine blade was optimized in terms of optimal chord length and twist angle distributions. The objective function used in the optimization study was the power coefficient, and the design parameters were the tip speed ratio, nominal wind speed, and the diameter of the rotor. Both experimental and numerical methods were used to investigate the aerodynamic performance of the optimized blades. Aerodynamic lift and drag coefficients were obtained experimentally for different low Reynolds numbers and angles of attack in a wind tunnel, while numerical simulations were conducted using Computational Fluid Dynamics (CFD) with the Transition k-kL-ω transition model. A flow visualization technique known as a smoke-wire test was carried out to analyze the flow patterns on the blades. The study resulted that the new turbine designs were more successful than the reference turbine in terms of power output. The reference turbine produced 1 kW at a wind speed of 11 m/s, while the new designs produced the same power at 9 m/s. Additionally, the reference turbine reached a maximum power of 1.2 kW at 13 m/s, while the new designs reached a maximum power of 1.46 kW at 10 m/s. These results indicated the success of the Novel ABC-BEM algorithm in optimizing the aerodynamic performance of small-scale turbine blades. This study provided an innovative approach to wind turbine design optimization and a new insight into wind turbine design.

Extended Blade Element Momentum Theory for the Design of Small-Scale Wind Turbines

Blade element momentum theory (BEMT) has been widely used in the design of the small scale wind turbine (SSWT). However, the original BEMT has weaknesses in providing the final design values of the wind turbine blade partly due to inaccurate assumptions of infinite number of blades made in deriving the theory. As such, the theory has to be amended in certain areas to form the so called the extended BEMT. In this study, a SSWT blade is designed using the extended BEMT method considering 3 factors: tip loss, low thrust at high axial induction factor, and high angle of attack in post-stall region where 5 correction models applying also the tip loss correction factor have been compared to the original BEMT model. The SSWT rotor has a diameter of 3m. An airfoil, SG6043 known for its suitability for SSWTs is used in this study. Furthermore, the blade geometry prior to the conduct of the shape optimization process are calculated using polynomial obtained from experimental procedures. The effect of infinite number of blades can be seen here to change the axial induction factor, especially at the tip of the blade and as a result increases the lift coefficient, and overpredicts the overall power coefficient and power of the wind turbine. With the Prandtl’s tip loss factor along with the correction model, the corrected final values of aerodynamic performances have been determined.

Effects of airfoil thickness on the aerodynamic efficiency of a small-scale wind turbine blade

Effects of airfoil thickness on the aerodynamic efficiency of a small-scale wind turbine blade

Effects of airfoil thickness on the aerodynamic efficiency of a small-scale wind turbine blade

Effects of airfoil thickness on the aerodynamic efficiency of a small-scale wind turbine blade

The Aerodynamic Performance of the Small-Scale Wind Turbine Blade with NACA0012 Airfoil

Small-scale wind turbine (SSWT) has been the subject of intensive research to complement its large-scale counterpart especially for usage in low wind speed regions. Two important issues that plague the development of the SSWT are its low in power coefficient especially due to the low Reynold’s number () condition that it’s operating in and the start-up difficulty that it faces. In this paper, the blade element momentum theory (BEMT) has been used to analyse a small-scale wind turbine having 3 m diameter. The airfoil used is the NACA 0012. The simplified experimental based equations have been used to determine the coefficient of lift, and coefficient of drag, of the airfoil. A developed MATLAB’s code applying the basic BEMT method is used. The results of aerodynamic performances including power coefficient, power and thrust are given as a function of wind speed, tip speed ratio (TSR) and Reynold’s number. It shows that at the minimum wind speed of 3 m/s, the wind turbine can have power coefficient of 43% but to produce 600 W of power that is required for total needs of electrical consumption of a household, the wind speed needed is 5m/s which is reachable for low wind speed region.

Preset angle, aspect ratio, and stall representations effects on the aeroelastic responses of small-scale wind turbine blades

This work provides an inclusive nonlinear aeroelastic study on the effects of horizontal axis Small-Scale Wind Turbines (SSWTs)’s preset angle of attack as well as aspect ratio on its aerodynamic stability. For this purpose, an enhanced nonlinear reduced-order model is established and a state–space formulation for the aerodynamics of a comprehensive wing-based aeroelastic system is constructed. This representation captures the influence of the preset angle of attack where the blade no longer displays an oscillatory motion around its zero-equilibrium point in the post-flutter region, instead, a new equilibrium point is introduced to the system through the incorporation of the preset angle. The effect of the preset angle on the blade stability is investigated by jointly performing linear analyses that provide insights on this parameter’s influence on the onset of flutter, accompanied with nonlinear analyses that evaluate the latter design parameter’s effect on the blade bending and torsion amplitudes in the post-flutter regime. Additionally, the Duhamel’s principle specific to low angles of attack is extended to represent unsteady flows with non-conventional lift curves of low aspect ratio blades while considering different representations of the aerodynamic stall. Results show the significant effect of the preset angle on both the onset of flutter as well as the post flutter amplitudes where the higher the preset angle, the higher the flutter speed. Furthermore, this research effort also demonstrates the importance of accurate lift modeling since ill-evaluated lift characteristics leads to a potential over- or under-estimation of the blade’s torsional and bending amplitudes post-flutter, and the conventional 2π slope assumption frequently used in various reduced-order-models within the literature seldom predicts erroneous onset of flutter values as well as inaccurate amplitudes in the post-flutter regime especially for the case of low aspect-ratio systems.

Optimal Design and Aerodynamic Performance Prediction of a Horizontal Axis Small-Scale Wind Turbine

The improved aerodynamic design of a horizontal axis small-scale wind turbine blade is crucial to increasing the efficiency and annual energy production of the turbine. One of the vital stages in aerodynamic design is the selection of the airfoil. Using the existing airfoils for a blade design which results in higher turbine characteristics is tedious. Consequently, this paper provides an optimal design strategy for a horizontal axis small-scale wind turbine blade through the multiobjective optimization of the airfoil using the Nondominated Sorting Genetic Algorithm II (NSGA-II). The latter outperforms the other commonly used genetic algorithms (GAs), as well as the Computational Fluid Dynamics (CFD) investigation of the different airfoil types and the wind turbine rotors on the steady or unsteady state aerodynamic performance. An NACA4412 airfoil with higher aerodynamic efficiency is considered as a baseline for the optimization in order to increase the lift coefficient and lift to drag ratio while avoiding excessive variations in the maximum relative thickness and area. The optimized airfoil (NACA4412-OPT) is used as the cross-sectional profile in the design procedure for a novel 1.15 m diameter three-bladed wind turbine rotor at a wind speed of 11.5 m/s, tip speed ratio of 4.65, and pitch angle of 0.2° by the Wilson design method. The two-dimensional analysis demonstrates that the optimized airfoil outperforms the other airfoils yielding the highest lift coefficient and lift to drag ratio, as well as a larger pitch range. The three-dimensional analysis shows that the time-averaged power coefficient value (0.33) of the new wind turbine is almost 26% higher and more stable than that of the original wind turbine while avoiding a high increase of the axial thrust.

Design and Optimization of a Small-Scale Horizontal Axis Wind Turbine Blade for Energy Harvesting at Low Wind Profile Areas

Wind turbine blades perform the most important function in the wind energy conversion process. It plays the most vital role of absorbing the kinetic energy of the wind, and converting it to mechanical energy before it is transformed into electrical energy by generators. In this work, National Advisory Committee for Aeronautics (NACA) 4412 and SG6043 airfoils were selected to design a small horizontal axis variable speed wind turbine blade for harvesting efficient energy from low wind speed areas. Due to the low wind profile of the targeted area, a blade of one-meter radius was considered in this study. To attain the set objectives of fast starting time and generate more torque and power at low wind speeds, optimization was carryout by varying Reynolds numbers (Re) on tip speed ratios (TSR) values of 4, 5, and 6. The blade element momentum (BEM) method was developed in MATLAB programming code to iteratively find the best twist and chord distributions along the one-meter blade length for each Re and tip speed ratio (TSR) value. To further enhance the blade performance, the twist and chord distributions were transferred to Q-blade software, where simulations of the power coefficients (Cp) were performed and further optimized by varying the angles of attack. The highest power coefficients values of 0.42, 0.43, and 0.44 were recorded with NACA 4412 rotor blades, and 0.43, 0.44, and 0.45 with SG6043 rotor blades. At the Re of 3.0 × 105, the blades were able to harvest maximum power of 144.73 watts (W), 159.69 W, and 201.04 W with the NACA 4412 and 213.15 W, 226.44 W, 245.09 W with the SG6043 at the TSR of 4, 5, and 6 respectively. The lowest cut-in speed of 1.80 m/s and 1.70 m/s were achieved with NACA 4412 and SG6043 airfoils at TSR 4. At a low wind speed of 4 m/s, the blades were able to harness an efficient power of 79.3. W and 80.10 W with both rotor blades at the TSR 4 and 6 accordingly.

An Inverse Method for Wind Turbine Blade Design with Given Distributions of Load Coefficients

It is shown in the literature that wind turbine designs with different load distributions have different wake features. To systematically study how different load distributions affect turbine wakes, a method for designing variants of blades with different radial load distributions, but with approximately the same power (CP) or thrust coefficient (CT), is needed. In this work, an inverse design method based on the blade element momentum method and the multi-dimensional Newton’s method, with the normal and tangential force coefficients as the design objective and iterations for satisfying the CP or CT constraint, is developed. The proposed method is validated using the two-bladed small-scale NREL phase VI S809 wind turbine blade design and the three-bladed utility-scale NREL 5 MW wind turbine blade design. Four variants of the NREL 5 MW wind turbine, i.e., the Root-CP, Tip-CP, Root-CT, and Tip-CT designs, which represent the variants of the original design (NREL-Ori) with a higher load near the blade root and tip regions with approximately the same power coefficient (CP) or thrust coefficient (CT) as that of the NREL-Ori design, respectively, are then designed using the proposed method. At last, the flapwise blade bending moment and the power coefficients from different variants of the NREL 5 MW turbine are compared for different tip speed ratios, showing that the “Root” designs are featured by a wider chord near the root, lower blade bending moment, and higher power coefficients for tip-speed ratios greater than nine.

Performance enhancement of a small-scale wind turbine featuring morphed trailing edge

The constant increase in reliance on sustainable energy resources is driving the research community towards adopting innovative and efficient wind turbine systems. A trailing-edge segment featuring seamless, wavelike, and continuous deflected layout is presented and integrated into a small-scale wind turbine blade. The study aims to quantitatively assess the potential of a moderately morphed (bumped) trailing edge in enhancing the power output of the wind turbines mainly at low wind velocity operating conditions. The National Renewable Energy Laboratory (NREL) Phase-II wind turbine is selected to be the benchmark model for the current quantitative analysis. Three-dimensional transient computational fluid dynamic (CFD) numerical analysis is established at three operating wind velocities using Ansys Fluent solver. The computed results of the baseline rotor blade are validated using data taken from the NREL/NASA-Ames experimental report. The implementation of a morphed (bumped) trailing edge shows a significant contribution in promoting energy harvesting with just a few degrees of smooth and gradual deformation. Compared to the baseline model, up to 53% in additional power gain is obtained from the rotor blade with integrated morphed (bumped) trailing edge segment. Thus, the compromised aerodynamic performance of stall-controlled small-scale wind turbines can be greatly improved with the utilization of morphing-capable trailing edge systems.

Experimental and simulation of aerodynamic performance of the small-scale wind turbine blades for usage in Malaysia

The enormous growth in manufacturing technology has contributed to the global climate change as well as the extinction of the conventional energies. The effort of replacing these energies with renewable energy found that the energy return of investment is high for wind energy. While the required minimum wind speed for operating efficient wind turbine is 3.5-7 m/s, certain locations in Malaysia meets the requirement for implementing the wind turbine. In this paper, a comparison is made between two wind turbines with equal blade length: the first turbine blade (TB1) does not use any airfoils while the second turbine blade (TB2) applies airfoils of SG6042, NACA4412, NACA5510 after undergoing shape optimization process. Both blades were fabricated using a 3D printing machine. Aerodynamic performances of the TB1 were studied through experimental work i.e. the turbine blade was given wind, flowing at several speeds in a wind tunnel. For the TB2, Q-blade software was used for conducting the shape optimization process and determining its aerodynamic performances. It was decided to use several airfoils throughout the blade length of the TB2. Experimental work was also conducted on the TB2 similar to the TB1. Analysis from Q-blade software showed that TB2 produces power efficiency of around 40%. It was found from the experiment that the TB2 gives twice amount of power compared to TB1.

Design of a small-scale wind turbine blade of glass fibre/epoxy composite for electrification of rural villages in Ethiopia: a case study

Design of a small-scale wind turbine blade of glass fibre/epoxy composite for electrification of rural villages in Ethiopia: a case study

Design of a small-scale wind turbine blade of glass fibre/epoxy composite for electrification of rural villages in Ethiopia: a case study

This paper targeted the design and stress comparison of a small-scale wind turbine blade which was constructed for the specific environmental conditions of the small rural village in Ethiopia. Firstly, the blade was designed from the characteristic of aerodynamic performance. Secondly, modelling and stress analysis of the windmills was conducted which is very significant for the further design and application of wind turbines. The material was epoxy-GFRP composite. The orthotropic mechanical properties of woven fibre epoxy polymer composite were created (ASTM D1683) with help of Autodesk Helius Composite V.16 software. The tensile and flexural testing specimens were fabricated by D3039M-17 and D7264M-15, respectively. Load, displacement, and modulus were investigated using UTM. Based on the parameters of the airfoil, the three-dimension and the assembly models of blades were mounted with the SOLIDWORK-V.16. Then the models were imported into ANSYS-V.15 WORKBENCH software for analysis. The displacement, Von Misses, and principal stress effects were determined.

Vibration-based monitoring of a small-scale wind turbine blade under varying climate conditions. Part I: An experimental benchmark.

SummaryStructural health monitoring (SHM) has been increasingly exploited in recent years as a valuable tool for assessing performance throughout the life cycle of structural systems, as well as for supporting decision‐making and maintenance planning. Although a great assortment of SHM methods has been developed, only a limited number of studies exist serving as reference basis for the comparison of different techniques. In this paper, the vibration‐based assessment of a small‐scale wind turbine (WT) blade is experimentally investigated, with the aim of establishing a benchmark case study for the SHM community. The structure under consideration, provided by Sonkyo Energy as part of the Windspot 3.5 kW WT model, is tested in both healthy and damaged states under varying environmental, that is, temperature, conditions as imposed by means of a climatic chamber. This study offers a thorough documentation of the configuration of this experimental benchmark, including the types of deployed sensors, the nature of excitation and available measurements, and the investigated damage scenarios and environmental variations enforced. Lastly, an overview of the raw and processed measurement data, made available to researchers via an open access Zenodo repository, is herein provided.

Airfoil types effect on geometry and performance of a small-scale wind turbine blade design

Airfoil types effect on geometry and performance of a small-scale wind turbine blade design

IMPLEMENTASI SENSOR MEMS AKSELEROMETER SEBAGAI ALAT PENGUKUR GETARAN PADA TURBIN ANGIN

Many techniques are available in the market to measure and analyze vibrations caused by rotating machines and the structure of the machine itself, but require expensive resources to identify the problem of damage. Generally these expensive equipment use conventional sensors such as eddy-current sensors, swing coil velocity sensors and piezoelectric transducer sensors to measure vibration. The implementation of a vibration measuring device in the form of an accelerometer sensor with a type of Micro Electro Mechanical System (MEMS) and a signal processing unit (Arduino Mega microcontroller) is used to measure vibrations that occur in small-scale horizontal type wind turbine blades. Experiments were carried out to check the accelerometer's ability to detect vibration response on wind turbine blades with the free vibration position. Then the signal in the form of the time domain will be converted into the frequency domain to get the dominant frequency value of the turbine blade, which is then analyzed to be compared with the B & K VibroPort 80 vibration meter. The experimental results show that the MEMS type accelerometer sensor can be applied to measure the free vibration conditions on wind turbine blades with an error percentage below 6%.

A Comparative Study of the Physical, Mechanical and Thermo-mechanical Behavior of GFRP Composite Based on Fabrication Techniques

The present study investigates the effect of fabrication techniques on the mechanical and thermo-mechanical behavior of bi-directional woven glass fiber epoxy composite for wind turbine blade application. The composites are fabricated by Vacuum Assisted Resin Transfer Molding (VARTM) and hand lay-up molding (HLM) techniques to identify the optimal performance output. The physical, mechanical and thermo-mechanical properties of the composites are evaluated for the samples fabricated by both the tecniques. It is observed that tensile strength, inter-laminar shear strength (ILSS) and flexural strength of the composites fabricated by VARTM technique are 405.62 MPa, 23.35 MPa and 239.3878 MPa respectively whereas composites fabricated by HLM technique shows slightly lower tensile strength (351.28 MPa), ILSS (16.75 MPa) and flexural strength (221.92 MPa). The intra-laminar mode-I fracture toughness test is also performed using compact tension specimen. The critical stress intensity factor (KIC) and critical strain energy release rate (GIC) are observed to be higher for VARTM composites. At the end, the dynamic mechanical analysis is performed to understand the material behavior and structural characteristics of these composites in high-temperature environment. This investigation purely governs the small-scale wind turbine blade structure in two different extreme climates from ambient to sustainable temperature.

Stress validation of finite element model of a small-scale wind turbine blade

Wind turbine blades are the first mechanical part of a wind turbine that interacts with the wind and hence play a key role in wind power generation. It is important that the wind turbine blade is tested for structural integrity in accordance to design code IEC 61400-23 such as strain limits, fatigue life, blade tip clearance limit, and surface stress. This paper aims to focus on the calculation and validation of static bending stresses in the blade; it presents the experimental and simulated stress analysis of a small-scale wind turbine blade. The simulation and 3D design software ANSYS, version 19.0 is used in the finite element analysis (FEA). By using FEA, we aim to capture the stress generated on the blade geometry under static loading and unloading conditions. As a first step towards this, the finite element results were validated against experimental results on a kestrel E230i turbine blade. The wind turbine blade was fixed at one end, loaded, and unloaded statically at three selected points. The finite element results are calculated within a 25% error margin of the experimental results. A reverse engineering procedure was used to determine the appropriate ANSYS model blade properties that were used as the exact material properties were not available from the manufacturer.

Optimized design and performance parameters for wind turbine blades of a solar updraft tower (SUT) plant using theories of Schmitz and aerodynamics forces

For extracting maximum power output from the wind, it is very important that the blades of a small wind turbine should rotate at any range of wind velocity. A step has been taken to estimate the optimized design and performance parameters of small scale wind turbine blades for a solar updraft tower (SUT). The pitch angle (β), relative wind angle (φ), lift force (dFL) and relative chord length (c/R) of rotor blade are estimated and optimized using conservation of angular momentum (Schmitz theory) and theory of aerodynamic forces on an airfoil. For different blade segments, dFL and power generation were evaluated and analysed. β, φ and dFL were optimised such as 18.4°, 26.4° and 0.0052 N, respectively, for achieving the maximum power output of 0.06 W at lower wind velocities (2 m/s). At higher wind velocities (10 m/s), the above parameters are optimised as 42.9°, 50.94° and 0.168 N, respectively for achieving a maximum power output of 1.75 W. The optimized values are compared with values from literature and these were found to be in reasonable agreement.