The Wind Turbine Design and Test

Considerable improvements in the aerodynamic performance of a vertical axis wind turbine (VAWT) can be achieved by integrating computational fluid dynamics (CFD) simulation and wind tunnel investigation in their design improvement. With the growing demand for energy worldwide, conventional sources are becoming more scarce and expensive. Wind is among the most popular and fastest growing sources of alternative energy in the world. It is an inexhaustible, indigenous resource, pollution-free, and available almost any time of the day, especially in coastal regions. Industry experts predict that, with proper development, wind energy could provide 20% of the nation’s energy needs. Vertical axis wind turbines (VAWTs) may be as efficient and practical as, and simpler, and significantly cheaper to build and maintain than, horizontal axis wind turbines (HAWTs). They have other inherent advantages; for example, they always face the wind. VAWTs include both a drag-type configuration, such as the Savonius rotor, and a lift-type configuration, such as the Darrieus rotor. The Savonius wind turbine is the simplest. Its operation depends on the difference in drag force when the wind strikes either the convex or concave part of its semi-cylindrical blades. It is good at self-starting and works independently of wind direction. However, its efficiency is relatively lower than that of the lift-type VAWTs. Due to its simple design and low construction cost, Savonius rotors are primarily used for water pumping and to generate wind power on a small scale and its large starting torque makes it suitable for starting other types of wind turbines that have inferior starting characteristics. Recently, some generators with high torque at low rotational speed, suitable for small-scale wind turbines, have been developed, suggesting that Savonius rotors may yet be used to generate electric power. The main goal of this research work is to improve the aerodynamic performance of the three bladed vertical axis Savonius wind turbine. Based on this goal, the objective of this project is to study the performance characteristics of the Savonius wind turbine scale models both experimentally and numerically. The turbine scale models will have different designs with different overlap ratios (ratio of gap between two adjacent blades and the rotor diameter) and without overlap within three blades. The experimental measurements and testing will be conducted in front of a low speed subsonic wind tunnel at different Reynolds number and the computational fluid dynamic (CFD) flow simulation around those design models will be performed by commercial CFD software FLUENT and GAMBIT.

The Savonius wind turbine is one types of vertical wind turbine that can be working in low wind speed conditions. This type of turbine is suitable for development in Indonesia, which has an average wind speed ranging from 3 to 5 m/s. This research presents the results of performance comparisons among three types of turbine blades, namely L, U, and S with each helix 60° and no-load conditions. Turbines are made of alumunium with a thickness of 0.7mm. The dimensions of the turbine are high 0.8m and the rotor diameter 0.46m, and each has three blades. The testing location was carried out on the seashore of Batu Belubang village, Bangka Island, Indonesia. The research was conducted to see how much the blade performance was by measuring the shaft rotation that occurred. From the results of the study, the three turbines showed excellent performance. Where for U blade type, the shaft can rotate up to 559 rpm at 5.5 m/s wind speeds. For type L blades with wind speeds of 5.6 m/s, the beam is capable of rotating up to 430 rpm. While for the type S showed the best performance on 564rpm at a wind speed of 5.5 m/s.

In South East Asia countries such Malaysia, wind turbine is generally not suitable to be used in large scale to generate electricity due to inconsistent wind speed and suitable land site availability. However, a small scale application is of preference as the wind speed in the region lies within the low speed range of approximately 2-5 ms−1 with intermittent highs up to 8 ms−1. The performance of Vertical Axis Wind Turbines (VAWTs) is known to be better compared to Horizontal Axis Wind Turbines (HAWTs) in urban conditions due to its omnidirectionality, which allows it to operate in fluctuating turbulent wind conditions. However, the major drawback of VAWTs is the inability to self-start under low wind speed conditions. Hence, the objective of this work is to investigate the Pivoting Panel Mechanism (PPM) which aims to assist VAWT models to self-start at low wind speed condition. Three sets of PPM width configurations (70mm, 80mm, 90mm) are used to study the effect of increasing the pivot panel surface area on the VAWT performance. Performance test showed that the PPM model improved the power coefficient values at the tip wind speed range of TSR<0.75 (PPM 70mm>80mm>90mm). Further investigation revealed that the larger PPM surface area (90mm) was able to assist the VAWT model to achieve a shorter RPM response time at wind speed of v = 2.5ms−1 and 2.9ms−1. These findings have considerable implications for future researches for the optimization of PPM design parameters and its adaptations in VAWT turbine design.

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. **

The need for energy and electricity has been increasing globally, and this means more power is required from the power plants. Power plants, however, will then continue harming the earth because of the greenhouse gasses produced while generating energies that contribute to global warming. Using renewable sources to produce clean energies is one of the sustainable methods to deal with such challenges. Wind energy is one of the renewable sources, which is accessible anywhere on earth, creating green energy. Wind turbines are mainly categorized into Horizontal Axis Wind Turbines (HAWT) and Vertical Axis Wind Turbines (VAWT). This paper firstly presents a general comparison between the HAWTs and VAWTs. Then, it presents mathematical modelling for the aerodynamic factors of HAWT and Darrieus VAWT to assist the researchers to understand some key design aspects of wind turbines, such as lift/drag ratio, tip speed ratio, power coefficient, and torque coefficient. Also, this paper presents a review of the aerodynamic performance of the recent VAWT designs to help researchers to identify and choose the best model among the Savonius and Darrieus rotors for further development or designing a new model at different wind conditions. This comparison review shows that for a large scale HAWT upwind 3 bladed wind turbines are the most optimum. The helical Savonius rotors perform better by having positive torque coefficient at all azimuth angles. Moreover, helical Darrieus was found to produce lesser noise and suitable for conventional areas. hybrid Savonius-Darrieus rotors can solve the self-starting challenge of the VAWTs, and they are suitable at low wind speeds. At last, this review shows some of the recent hybrid Savonius-Darrieus rotors which would help to solve the low efficiency of Savonius rotor and self-starting challenge of Darrieus rotors.

Impacts of solidity and hybrid system in small wind turbines performance

CFD simulations were conducted for these types of wind rotors to address the increasing focus of scholars in the renewable energy sector on studying the adoption of sustainable energy sources and reducing fossil fuel consumption. Vertical axis wind turbines (VAWTs) have become increasingly prevalent for wind power generation. This work presents a computational analysis of the performance of a vertical-axis wind turbine for three designs using Fluent 2020 R2 CFD software. The three designs' three-dimensional computational fluid dynamics (CFD) were compared using the k-epsilon augmented wall treatment as a turbulence model at an airflow velocity of 5 m/s. From this study, it can be concluded that it is possible to use this type of hybrid wind turbine in areas with low wind speeds due to their quick response to rotation. For these reasons, this type of hybrid wind turbine can be used in residential areas as a practical application, since these areas are characterized by low wind speeds in most cases.

Depleting oil reserves and fossil fuels has changed the aspect of thought in energy sector and led to a strong focus on renewable energy sources. Wind energy sector is a potential area of research as the idea of micro grid and domestic power integration are in place. Wind turbines that can be used to harness the low wind velocities for power generation are of importance. Horizontal Axis Wind Turbines and vertical Axis Wind Turbines are the types of wind turbines used to convert wind energy to electrical energy. Horizontal Axis Wind Turbines provide good wind power conversion efficiency and are used in regions of moderate to high wind speeds and in regions of lower wind speeds, Vertical Axis Wind Turbines performance is satisfactory. In this work, the mathematical modeling of HAWT and different types of VAWTs are presented, followed by analysis of those turbine models under lower air velocities. The performance parameters used in this study are maximum power coefficient and output power which are standard performance metrics for wind power generation. The analysis reinforces the fact that, in domestic conditions, where the wind velocity in low, VAWTs provide superior performance.

Considering the aero-hydro-mooring-control coupled performance of a floating Vertical Axis Wind Turbine (VAWT), the numerical model of the floating helical VAWT system is established, and the fully coupled simulation program of the floating helical VAWT is developed. The aerodynamic load of the wind turbine system is calculated using the unsteady BEM model, and the hydrodynamic load is calculated using the 3D potential theory. The floating foundation is considered as a rigid body, and the blades and tower are considered as flexible bodies. Based on the Kane method of a multi-body system, the dynamic responses of the VAWT could be solved in the time domain. A variable speed control model considering efficiency and load is established to match the rotating speed with the wind speed, and it could maintain the target output power under the influence of turbulent wind and large-scale movement of the floating foundation. The control strategy of limiting the target speed change rate and low-pass filtering is adopted to ensure the rapid regulation of the wind turbine under low wind speed conditions and stable regulation under high wind speed conditions.

This article introduces a new wind turbine, called resistance type vertical axial wind turbine (VAWT) with soft blades. The blades of the new turbine resist the wind and collect the power along the wind direction, while canceled the resistance against the wind direction. The new work mechanism was conceived to improve the aerodynamic performances of traditional VAWT. To prove the above supposing, two wind turbine models with soft blades were set up to find the static torque coefficients by numerical study. The simulation results of both models were compared with the experiment data of Savonius wind turbines models with the same sweeping area. The simulation results showed that: 1) The comparison between experiment data and CFD analysis on the same Savonius wind turbine has the reliability; 2) The soft bladed VAWT produces no negative static torque and it starts normally under low wind speed condition.

Energy is important for the development of human civilization. As conventional energy exhausts, the development of clean and renewable energy, such as wind and solar becomes ever important to people’s live. The wind power has been harnessed by mankind for a long time and the associated technology is more advanced than other clean energies. Nowadays wind power increasingly attracts interests and its utilization has entered a rapid development stage. There are two types of wind turbines, namely horizontal-axis wind turbine (HAWT) and vertical-axis wind turbine (VAWT). The latter has many advantages, such as low cost, simple-structured blades, convenient installation and maintenance, and the ability to utilize wind from all directions without the need of a steering mechanism. A special VAWT implemented with magnetic suspension and self-pitch blade design will be introduced in this chapter. It not only has the advantages of traditional VAWT, but also the advantages of low threshold starting wind-speed, high wind power efficiency, etc. Discussion in this chapter includes the benefits of applying magnetic bearing technology to the wind turbine. Specifically, the entire wind turbine rotor weight can be supported by magnetic bearings. The friction of the bearings is essentially non-existence. There is no need for bearing lubrication, and the maintenance cost can be reduced. Furthermore, the magnetic suspension technology can eliminate mechanical vibration and reduce noise. Since low friction also reduces starting torque, the magnetic bearings enable producing power at lower wind speed than conventional bearings. The discussion also includes a blade-pitch adjusting technique. Conventional VAWT applies special blade adjusting mechanism which is complicated in structure, costly to fabricate and wastes power. Herein, the blades in a magnetic suspended VAWT are designed to adjust the pitch automatically and do not require any dedicated special devices. The blade pitch is adjusted naturally during rotation for the best windward angle. As a result the blades always produce the maximum thrust wind force improving the wind turbine efficiency. Thus, the magnetically suspended and self-pitched vertical-axis wind turbine will be designed with uncomplicated structure, high efficiency and low cost.

A vertical-axis wind turbine (VAWT) is a type of wind turbine where the main rotor shaft is set transverse to the wind (but not necessarily vertically) while the main components are located at the base of the turbine. The performance of a Vertical Axis Wind Turbine (VAWT) is closely related to its Tip Speed Ratio (TSR). It is not easy to know beforehand which TSR will result in maximum power extracted from the VAWT. The objective is to model and simulate a 2D H-type VAWT in an open-source OpenFOAM CFD solver. The turbulence model used is k-Omega SST (Shear Stress Transport), and the rotating domain is set up using Arbitrary Mesh Interface (AMI) and dynamicMeshDict in OpenFOAM. Due to the transient nature of the simulation, pimpleFoam solver is used to simulate VAWT. Forces and Moments are reported after certain timesteps to obtain the torque Vs. Time curve for different TSRs. The simulation is carried out for different TSRs, and the graph of Coefficient of Power (Cp) Vs. TSR is plotted. It is found that the Cp first increases with an increase in TSR up to 0.35, and then Cp decreases. Such type of analyses can be used as a low-cost basis to obtain boundary and initial conditions or obtain baseline input parameters for 3D simulation of VAWTs.

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 this study, performance of different wind turbines is compared with using QBlade software. Normally wind turbines are categorized as Horizontal Axis Wind Turbine (HAWT) and Vertical axis wind turbine (VAWT) which in this paper Darrieus type as a VAWT is discussed with HAWT. The airfoil selected for this study is NACA 0012 and from simulations it can be resulted how adding blades influence efficiency in wind turbines. In terms of using wind turbines, number of blades is one of the important parameters. QBlade contains the XFOIL airfoil analysis functionalities which makes a software a single tool that comprises all functionality needed for the design and simulation of vertical and horizontal axis wind turbines. The benefits of the proper airfoil design optimal is increasing the efficiency of wind turbines and maximization of the power produced.

India's energy demand is rising in order to meet the country's current economic development ambitions. The provision of growing amounts of energy is a necessary condition for a country's economic growth. India is heading toward a trend of generating power from renewable resources, owing to the maturity of technological innovations and the pressing need to preserve a healthy environment at a fair cost. Wind energy sector has increased from a fringe activity to a huge multinational business thanks to its safer and environmentally friendly properties. This project aims at utilizing wind energy in an effective approach to get the maximum electric output, which can be implemented in urban areas on the ground, on highways etc. In the present work, vertical axis wind turbine is designed numerically. The blades used are twisted and are connected to the shaft. Analyses are carried out on two vertical axis wind turbine profiles at different wind speeds. Velocity, pressure, and torque characteristics are obtained and compared between the two vertical axis wind turbine models. In hybrid vertical axis wind turbine consist of H-Darrius wind turbine is a type of vertical axis wind turbine