Experimental and computational study on aerodynamic performance of HAWT

In recent decades, wind turbines have emerged as substantial renewable energy technologies, particularly for offshore applications. However, the utilisation of conventional wind turbine in regions characterised by a low wind speed profile, such as Malaysia, remains limited. To address this gap, this study develops an unconventional small-scale Vertical Axis Wind Turbine (VAWT) provision for offshore application in Malaysia’s low wind speed regions. The study commenced with a wind feasibility analysis which aimed to determine the viable range of offshore wind speeds prior conducting wind tunnel tests. The VAWT model was designed using SolidWorks software, fabricated using a 3D printer and tested in the National Defence University of Malaysia (UPNM) wind tunnel lab facilities. Through a systematic analysis and optimisation of blade diameters, stages and angles using Taguchi method, this study aimed to enhance the wind turbine performance in terms of power coefficient (Cp) and tip speed ratio. The result highlighted the pivotal role of blade diameter and the number of stages as a key design factor for VAWT, with the optimal configuration of blade diameter of 16 cm, a single stage and Angle of Attack (AoA) of 7°, resulted in a Cp value of 0.622. It is important to note that this Cp value exceeds the typical wind turbine power coefficient benchmarks, which range from 0.3 to 0.45, indicating that the optimised design offers a higher-than-average efficiency for small-scale VAWTs. Additionally, variations in AoA were found to be the least significant design factor, as all models demonstrated peak Cp values corresponding to wind speeds. Although tested in a controlled wind tunnel environment, these results suggest that the optimum design could perform efficiently under Malaysia's real-world offshore conditions, where wind speeds are typically low. This study provides key design considerations for small-scale VAWTs in low wind profile regions, contributing to the sustainable development of wind energy in Malaysia.

In recent years, sites with low annual average wind speeds have begun to be considered for the development of new wind farms. The majority of design methods for a wind turbine operating at low wind speed is to increase the blade length or hub height compared to a wind turbine operating in high wind speed sites. The cost of the rotor and the tower is a considerable portion of the overall wind turbine cost. This study investigates a method to trade-off the blade length and hub height during the wind turbine optimization at low wind speeds. A cost and scaling model is implemented to evaluate the cost of energy. The procedure optimizes the blades’ aero-structural performance considering blade length and the hub height simultaneously. The blade element momentum (BEM) code is used to evaluate blade aerodynamic performance and classical laminate theory (CLT) is applied to estimate the stiffness and mass per unit length of each blade section. The particle swarm optimization (PSO) algorithm is applied to determine the optimal wind turbine with the minimum cost of energy (COE). The results show that increasing rotor diameter is less efficient than increasing the hub height for a low wind speed turbine and the COE reduces 16.14% and 17.54% under two design schemes through the optimization.

The effective exploitation of renewable energy sources is one of the most effective solutions to counter the energy, environmental and economic problems associated with the use of fossil fuels. Small-scale wind turbines (converting wind energy into electric energy with a power output lower than 50 kW) have received tremendous attention over the past few decades thanks to their reduced environmental impact, high efficiency, low maintenance cost, high reliability, wide wind operation range, self-starting capability at low wind speed, limited installation space, reduced dependence on grid-connected power and long transmission lines, low capital costs, as well as the possibility to be installed in some urban settings. However, there are significant challenges and drawbacks associated with this technology from many different perspectives, including the significant discrepancy between theoretical performance data provided by the manufacturers and real field operation, that need to be investigated in greater depth in order to enable a more widespread deployment of small-scale wind turbines. In this review, a complete and updated list of more than 200 commercially available small-scale horizontal and vertical wind turbine models is provided and analysed, detailing the corresponding characteristics in terms of the number and material of blades, start-up wind speed, cut-in wind speed, cut-out wind speed, survival wind speed, maximum power, noise level, rotor diameter, turbine length, tower height, and specific capital cost. In addition, several scientific papers focusing on the experimental assessment of field performance of commercially available small-scale horizontal and vertical wind turbines have been reviewed and the corresponding measured data have been compared with the rated performance derived from the manufacturers’ datasheets in order to underline the discrepancies. This review represents an opportunity for the scientific community to have a clear and up-to-date picture of small-scale horizontal as well as vertical wind turbines on the market today, with a precise summary of their geometric, performance, and economic characteristics, which can enable a more accurate and informed choice of the wind turbine to be used depending on the application. It also describes the differences between theoretical and in-situ performance, emphasizing the need for further experimental research and highlighting the direction in which future studies should be directed for more efficient design and use of building-integrated small-scale wind turbines.

For a wind turbine to extract as much energy as possible from the wind, blade geometry optimization to maximize the aerodynamic performance is important. Blade design optimization includes linearizing the blade chord and twist distribution for practical manufacturing. As blade linearization changes the blade geometry, it also affects the aerodynamic performance and load characteristics of the wind turbine rotor. Therefore, it is necessary to understand the effects of the design parameters used in linearization. In this study, the effects of these parameters on the aerodynamic performance of a wind turbine blade were examined. In addition, an optimization algorithm for linearization and an objective function that applies multiple tip speed ratios to optimize the aerodynamic efficiency were developed. The analysis revealed that increasing the chord length and chord profile slope improves the aerodynamic efficiency at low wind speeds but lowers it at high wind speeds, and that the twist profile mainly affects the behaviour at low wind speeds, while its effect on the aerodynamic performance at high wind speeds is not significant. When the blade geometry was optimized by applying the linearization parameter ranges obtained from the analysis, blade geometry with improved aerodynamic efficiency at all wind speeds below the rated wind speed was derived.

This report presents the study of fluid-structure interaction (FSI) of a 5kW horizontal axis wind turbines (HAWT). The motivation of the current investigation is to address the FSI problem of HAWT in the whole flow field analysis with hybrid turbulence model method which is used to find out the flow and structure characteristics of wind turbine in operation under different tip speed ratio (TSR). The target of current work is to obtain detailed information of flow field and structure response simultaneously using the finite element analysis (FEA) method as well as providing new reliable and accurate approach which could be quickly and economically employed in wind turbine FSI problem analysis. In this report, a detailed and comprehensive literature review related to FSI problem of wind turbine has been presented and includes aerodynamic, wind turbine theory, computational fluid dynamic, fluid structure interaction and aeroelastic stability. A 5kW wind turbine is designed according to blade element momentum (BEM) method and a 3D wind turbine modeling is generated in SolidWorks. The 3D wind turbine modeling is imported into FEA software by coupling with the structure domain and the fluid domain to achieve FSI analysis and different TSR are applied to the computational fluid dynamics (CFD) analysis to gain the wind turbine operation information under different scenarios. The simulation results are investigated to reveal the influence of the FSI phenomenon on wind turbine performance. Analysis of wind turbine aeroelastic stability is conducted to prevent blade from experiencing flutter problem. A multiple objective optimization method for wind turbine design including aerodynamic and structure has been developed to improve wind turbine performance. The flow field analysis results showed that the strength of vortex at the tip and root of the blade increases as wind speed increases when wind turbine is under operating conditions. With wind speed of 10m⁄s, most of the flow over the lower surface remains attached and the wind turbine blade was running under design condition. As the wind speed increases, flow separation emerges. When the wind speed increasing to 16m⁄s, the wind turbine blade works under deep stall condition. The wind turbine power coefficient drops continuously from 0.46 to 0.22, as wind speed increased from 10m⁄s to 20m⁄s. The comparison of wind turbine power and torque coefficient under different CFD configuration shows the advantage of whole flow field analysis with hybrid turbulence model. The structural analysis results demonstrated that most of the pressure force acts at a region around the 1⁄4 chord from the leading edge of the blade under operating condition and the displacement of blade tip in flap direction is bigger than those in the other directions. Modal analysis results deduced that flap is the main type of vibration in first and second modes. The difference of natural frequency between single blade and blade rotor becomes larger as vibration order increases. The dynamic performances of wind turbine blade and rotor are totally different and show the whole flow field method is better than the one third domain method. The wind turbine aeroelastic analysis results illustrate that the bending frequency and torsion frequency are around 23.94Hz and 38.46Hz respectively under TSR=4 and both move towards 30Hz under TSR=1.7. When TSR is smaller than 1.7 the wind turbine will experience flutter due to the overlapping of bending and torsion frequencies. The multiple objectives optimization method takes the aerodynamic performance and blade loading into account to gain better design parameter. The comparison between initial and optimal design shows that optimized method could provide higher electrical energy around 1073kW•h per annum under rated wind speed. The optimized wind turbine critical flutter wind speed will increase from initial design speed of 35m/s to 38m/s under optimization design.

Increasing environmental concerns have led to a demand for more environmentally friendly energy options. Worldwide, wind energy is one of a clean, renewable source of green electricity. Fossil fuel is one of our most important sources of energy and its quantities are decreasing. However, wind is a renewable resource that can as stand by source with fuel. Wind turbines are used to harness the wind to generate energy. Vertical axis wind turbines (VAWTs) are suitable for use in built sites because to their outstanding features, attractiveness, low noise, and safety. To achieve these objectives, vertical axis wind turbines with multiple blades (blades are made from polyvinyl chloride (PVC) material) have been designed, manufactured and studied experimentally to investigate its performance. Turbine’s blade is a half cylinder in its shape. The blades rotational speed of the blades, the resulted torque (T), and generated power (P) of each configuration of the suggested turbine were determined for different wind speeds (1.5m/s, 2.5m/s, and 3m/s) and rotor radius of (30cm, 40cm, and50cm), respectively. The graphical relation between coefficient of power (Cp) and the tip speed ratio (TSR) and between coefficient of power (Cp) and angles of the blades were constructed. It was noted that performance of wind turbine is largely depends on wind speed, blade locations, and blade angle. The maximum value of the power coefficients (Cp = 13.056%) is noticed at 40cm and 1.5 m/s for blade radius and wind speed, respectively, specifically at TSR=1.3 and 450 blade angle. The maximum values of the Cp for all values of the effective parameters are noticed at 450 blade angle. In addition, higher values of Cp are achieved at the lower wind speeds and high blade radius, and that corresponds to higher TSR. Finally, VAWT is able to generate electricity for local use even at low wind speeds.

PurposeThe rapid rising of renewable energy sources particularly wind energy cannot be ignored. The numerical increase in wind energy farms throughout the world is the best example. The purpose of this paper is to assess the basic question of whether wind characteristics affect the performance and cost of energy. The importance of this question cannot be ruled out while comparing renewable energy to a conventional form of energy more specifically especially for the developing country where the cost of energy is very high.Design/methodology/approachThe research design of this paper is consists of an assessment of local wind characteristics of the wind farm site using Weibull k and c parameters. The performance model is used to assess the performance of the wind turbine (WT) corresponding to local wind characteristics. The wind correlation with WT in terms of changing wind speed has been assessed to quantify the effects of wind speed on the WT behavior and failure of WT components. Similarly, the power curve of WT is assessed and compared with the International Electrotechnical Commission standards 61400-12-2. The WT power coefficient and tip speed ratio corresponding to wind speed is also investigated. The energy volume and cost of energy lost model is used to determine the cost and volume loss of energy/kWh of the wind farm.FindingsThe findings of practical wind farms showed that the wind conditions of the site are showing a strong tendency that can be determined from the results of Weibull k and c parameters. The k and c parameters are observed to be 3.44 and 9.16 m/s, respectively, for a period of a year. The standard deviation is observed to be 2.56 for a period of a year. WT shows the efficient behavior can be obtained from the power coefficient and tip speed of WT at different wind speeds. Also, wind farm observation showed that to be some increasing wind speed cause of based WT component failures. The results of energy volume and cost/kWh assessment showed that the major portion of energy volume and cost of energy is lost owing to network, voltage dip and frequency surge, electrical and mechanical components failures.Originality/valueGenerally, it can be concluded that the WTs are now able to cope with variable wind speeds. However, the results of this paper are showing that WT performance and availability decreased due to increased wind speeds. It can also be a reason to decreased volume and increase the cost of energy/kWh.

A wind turbine power plant (WTPP) is a renewable energy system that harnesses wind energy to generate electricity. Indonesia has been identified as a region with considerable wind energy potential, making it a promising location for developing this technology. In alignment with this potential, the Indonesian government has set a target of approximately 7 GW of installed wind turbine capacity by 2030. This study examines the influence of blade angle on the efficiency of electrical energy generation. Three blade angle variations—20°, 30°, and 40°—were analyzed using an experimental setup featuring a horizontal-axis wind turbine with five blades and a constant wind speed of 6.2 m/s. The rotation of the blades converts wind energy into kinetic energy, which is subsequently transferred to a generator to produce electricity. Experimental investigations were conducted using a laboratory-scale prototype, revealing that a blade angle of 40° achieved the highest efficiency. Specifically, the turbine exhibited an efficiency of approximately 29% after 3 minutes of rotation, which increased to 42% after 8 minutes. These findings highlight the pivotal role of blade angle optimization in enhancing WTPP performance. Moreover, this study provides a valuable reference for advancing wind energy applications in Indonesia, supporting the transition towards more sustainable and efficient renewable energy solutions.

The horizontal-axis wind turbine (TASH) is a wind energy technology that can generate electricity, but its performance still has to be improved. To determine how much an aspect ratio affects wind turbine performance, this study used a horizontal-axis wind turbine with three spiral blades and an aspect ratio of 0,116. The primary performance metrics of horizontal-axis wind turbines with three spiral blades and an aspect ratio of 0,116 are to be measured and examined in this work. Understanding how aspect ratio affects voltage (volts), current (amperes), torque (τ), turbine rotational speed (rpm), and in line with wind speed (ρw) in the process of generating electrical energy is the specific goal. A horizontal-axis wind turbine with three spiral blades and an aspect ratio of 0,116 will be constructed and tested in a controlled setting as part of this research's experimental methodology. The systematic measurement of essential performance characteristics, such as wind speed, torque, turbine rotational speed, voltage, and current, will provide a comprehensive understanding of the wind turbine's ability to generate electrical energy. The TASH experiment 3 spiral blades with an aspect ratio of 0,116 yielded the highest value when tested using a planetary gearbox at 24,23 rpm, 53,09 V of voltage, 1,25 A of electric current, and 30,94 Nm of torque at 5,0 m/s of wind speed. In the calculation of the power coefficient, torque coefficient, and tip speed ratio, the minimum value obtained in the test without a planetary gearbox was 0,0231 at wind speed 2,5 m/s, 0,2183 at wind speed 2,5 m/s, and 0,1059 at wind speed 2,5 m/s. The minimum value is obtained in the TASH test without a planetary gearbox with a rpm value of 105,89 rpm, Voltage 8,60V, Electric Current 0,05A, and Torque 2,85Nm at wind speed 2,5 m/s. A planetary gearbox with a power coefficient of 0,4713 at a wind speed of 4.5 m/s, a torque coefficient of 0,6813 at a wind speed of 4,0 m/s, and a tip speed ratio of 0,7525 at a wind speed of 5,0 m/s was used to test the system and determine the maximum value.

I.IntroductionThe vertical axis wind turbine has been widely concerned because of its advantages such as multiphase wind, stable force, easy installation and maintenance, and small starting wind speed. Vertical axis wind turbines mostly use permanent magnet synchronous generators or doubly fed induction wind turbines, and most of them are axial flux permanent magnet generators[1]. Compared with doubly fed induction wind turbine, permanent magnet synchronous generator (PMSG) has the advantage of high power density and is the main research object of vertical axis wind turbine. However, the direct coupling of the high power axial flux permanent magnet synchronous generator and wind turbine causes the starting of the wind turbine to become more difficult. In order to improve the starting performance of vertical axis wind turbines, maglev technology is considered to reduce the starting resistance as the development direction of vertical axis wind turbines. Therefore, an asymmetric-primary axis-flux hybrid- electricity generator is proposed in this paper, and the decoupling control of levitation force and output power is implemented using asymmetric primary and hybrid excitation.II.operation principleThe proposed asymmetric-primary axis-flux hybrid-excitation generator for the vertical axis wind turbine structure is shown in the Fig.1.The generator is composed of double stator primary and single actuator. The double stator primary has an asymmetric structure design, and the rotor shaft is connected with the wind turbine shaft to realize direct drive wind power generation. The rotor adopts the spacing design of permanent magnet and modulating tooth to reduce the consumption of permanent magnet. Both the excitation winding and the armature winding are located in the primary stator, so the mixed excitation and magnetic field can be adjusted without adding any mechanism such as brush slip ring, which reduces the complexity of the structure.In general, the proposed generator has the following characteristics(1) The flat structure shortens the axial length of the generator and is suitable for direct drive of vertical axis wind power generation system.(2) The levitation force is provided by bilateral unbalance design of axial flux. The two sides adopt different primary sizes, and then the axial electromagnetic force imbalance of the bilateral air gap forms the suspension force, which avoids adding active and passive levitation mechanisms and reduces the complexity of the overall system.(3) The levitation force and output power are controlled by hybrid excitation. The primary tooth DC excitation is adopted to realize zero crosslinking of the excitation with permanent magnet and armature, and the levitation force regulation does not affect the output power. The system can start at low wind speed, and the levitation force and total output power can be adjusted according to the change of wind speed. Through free distribution of bilateral power to achieve the total power following the wind speed and the levitation force following the lift force of the wind turbine.(4) Using magnetic field modulated axial magnetic field structure, the rotor structure is simple and reliable. If the pole pair numbers of rotor and armature are pr and ps, and the number of the stator tooth is pn, there is pr = pn±ps. The design makes it have the magnetic field modulation effect, which can increase the magnetic field change rate under the low speed, thus increasing the generation power.(5) The use of concentrated armature windings and excitation windings reduces the end, thus reducing magnetic leakage and losses.III.simulation and resultsA three-dimensional finite element model of the asymmetric-primary axis-flux hybrid-excitation generator is established, and the no-load characteristics and load characteristics of the generator are obtained. The no-load characteristics under different excitation current are simulated, and the flux linkage of armature coils and DC excitation coils are shown in Fig.2.We can see that when different excitation currents are applied, the crossing flux linkage between DC excitation winding and secondary permanent magnet is almost 0, and DC flux has little effect on the armature flux. Therefore, When the excitation changes, the unilateral levitation force changes only in amplitude, but there is no harmonic phase shift, and positioning torque is almost unaffected. he proposed generator has good decoupling performance of levitation force, output power, and DC excitation. In addition, the optimization design of the generator is further studied such as pole arc coefficient, positioning moment and pole slot ratio. IV.conclusionIn this paper, we proposed an asymmetric-primary axis-flux hybrid-excitation generator, studied the no-load characteristics, load characteristics and excitation characteristics, and optimized the structural parameters of the generator. The simulation results are obtained, and state that the generator can realize the decoupling of the levitation force of excitation and power, which is suitable for vertical axis wind turbine. **

To harness wind energy in low wind speed areas, a vertical axis wind turbine (VAWT) is generally more suitable than a horizontal axis wind turbine. To improve the feasibility of using a VAWT, a magnetic levitation bearing concept, utilizing neodymium magnets, is used to make the bearing frictionless. A new experimental type of airfoil called EN0005 is used that boasts better self-starting ability than conventional airfoils. The design parameters of the wind turbine are explored and reviewed to create a final design that is modelled in SolidWorks. This final design is then put through simulations and analysis in ANSYS FLUENT before being fabricated as a prototype. This final prototype produces similar results to other findings and validates the report. The EN0005 blade profile appears to improve the self-starting capability of the wind turbine and improve viability of Darrieus turbines in lower wind speeds. These findings verify the benefits of using a magnetic frictionless bearing for wind turbines.

An ALQR (Adaptive Linear Quadratic Regulation) method for the variable speed wind turbines system is proposed in this paper. The controller is designed for the wind turbine operating in the low wind speed (Region 2), in which the pitch of the blades is fixed at the optimal angle. Since the wind turbine is a nonlinear system, the Kalman filter and the adaptive method are implemented in the controller to make the LQR compatible with the nonlinear system. The proposed control scheme is compared in the simulation with several commonly used control methods, i.e. look-up table, PID control and gain-scheduling method. The step changed wind speed profile and the turbulent wind speed profile are adopted for the tests. The results of the simulations show that the proposed ALQR method is much better than the conventional methods.

Analysis on aerodynamic performance of mine horizontal axis wind turbine with air duct based on breeze power generation

Controller design for a wind farm, considering both power and load aspects

This paper presents an improved approach to assess wind turbine reliability considering the impact of hub levels using Monte Carlo simulation. The hub level of wind turbine affects wind turbine reliability in two aspects: 1) different hub levels are subject to different wind speeds, which produce different wind power outputs; 2) due to the correlation between wind speeds and turbine failure rates, wind turbines with different hub levels have different rates of failure. Therefore, it is important to consider the wind turbine's height, particular hub levels, when evaluating wind turbine reliability. The purpose of this paper is to develop a model to evaluate wind farm reliability while considering the effect of hub levels on wind turbine output and on wind turbine failure rates. The proposed approach is tested on the IEEE RTS-79 system with relevant modifications using probabilistic simulation. The efficacy of the approach is verified by evaluating reliability indexes of wind farms when the hub levels of wind turbines are taken into account.