Vertical Blades Research Articles

Numerical analysis of vertical axis wind turbine blades in ANSYS Fluent

The limitation of the source and storage of fossil fuel and the rapid mitigation due to the rise of population, the renewable energy is the only key for the problem. Among the renewable energies, wind energy becomes the most promising potential as it is a green energy, and this research is focused on the same. The present study investigates the wind turbine blade simulation analysis for a vertical axis wind turbine blade based on the design parameters of NACA0018 airfoil. In this investigation, computational fluid dynamics analysis of vertical axis wind turbine blade is simulated by varying the angle of attack ranging from 12° to 15° while maintaining an incoming wind velocity of 8 m/s. Finite difference-based software “ANSYS FLUENT” is utilized for the simulation of this angle of attack analysis on vertical axis wind turbine considering the turbulence to be SST k-∊ model. Vertical axis wind turbine’s efficiency surely depends upon the blade profile and its orientation. Throughout the blades, velocity and pressure distribution is analyzed at different tip speed ratio with constant inlet velocity. The parameters like tip speed ratio, lift coefficient and power coefficient are reported in this study. In this study, at various angle of attack, simulation shows the uniform velocity distribution at optimum angle of attack of 15° and validation is done by drafting a graph between power coefficient and tip speed ratio, and for given angle of attack, lift coefficient is also validated via graph and feasible value of 1.689 is obtained from the simulation at angle of attack of 15° and comparison is also done by using velocity and pressure contours of blades at different angle of attack.

Concept design and numerical analysis of hybrid solar–wind turbine

A wind turbine is a device that converts wind energy to electrical energy. External factors such as wind speed and direction shift, as well as turbine blade design considerations, cause a significant amount of energy to be wasted throughout the conversion process. Considering all these losses, a turbine’s average efficiency is roughly 45 percent. The blades of a wind turbine are one of the most crucial factors in determining the turbine’s efficiency. The design and geometry of the blades have a direct impact on performance since it determines how much kinetic energy from the wind is converted into mechanical energy. Many concepts and technologies are being used to improve the efficiency of wind turbines while lowering their maintenance costs. Wind turbines based on their axis orientation are classified as vertical axis and horizontal axis. Vertical axis wind turbines are not as widespread as their horizontal-axis counterparts due to their lower efficiency. In this study, we will use a Savonius vertical axis wind turbine to investigate a way of enhancing its efficiency by installing solar panels on its vertical blades and determining the best performance angle at which the turbine should be kept achieving maximum efficiency. Computation fluid dynamic analysis and thermal and structural analysis has been performed to check the efficiency of the designed blade. As a result, an optimized wind turbine design has been developed.

Design and Manufacturing Method of GFRP Blades for Vertical Axis Wind Turbine

Today, environmental protection and the rational use of natural resources have become growing challenges. One of these aspects is energy producing with less impact on the environment. For some applications the small wind turbines can be a solution. In this paper are presented some aspects regarding the design and manufacturing technology of 500 W vertical axis wind turbine blades. The turbine will be installed in the urban environment so that requirements regarding rotor aesthetics and noise level will be considered. The optimal geometric parameters of the turbine rotor were determined by specialized MathCAD and elaborated in 3D modelling software. For the blades the NACA 0018 airfoil was used with the chord length of 110 mm and is constant throughout the length of the blade. The blades are helical and are 1800 mm long. To estimate the aerodynamic performance of the turbine rotor, a computational fluid dynamics model was developed using ANSYS CFX finite element analysis software. The authors proposed a new method for rapid prototyping of blades using fused deposition modelling procedure. In order to increase the mechanical properties, the blades were covered with several layers of glass-fibres reinforced polymer. Estimation the blade strength to operating loads was performed using Ansys Workbench software. The modelling of the composite material architecture on the blade surface was performed using the special ANSYS Composite PrepPost module. Several simulations were performed with different number of layers and stacking sequences. In order to prevent rotor over engineering the maximum rotation speed of 400 min−1 was accepted (equivalent to ≍12 m/s wind speed). Simulation of the blade strength to operating loads indicate values of around 40 MPa for shear stress (50% less than failure shear stress) and around 80 MPa principal stress (60% less than failure tensile stress). The maximum blade deformations of 3 – 4 mm shows that the blade is stiff enough at imposed operation conditions. For the blade manufacturing, based on the numerical analysis results, the configuration of the strength structure composed of 5 layers of GFRP was selected, which forms a total blade weight of 1895g.

Aerodynamic Characteristics of a Single Airfoil for Vertical Axis Wind Turbine Blades and Performance Prediction of Wind Turbines

The design of wind turbines requires a deep insight into their complex aerodynamics, such as dynamic stall of a single airfoil and flow vortices. The calculation of the aerodynamic forces on the wind turbine blade at different angles of attack (AOAs) is a fundamental task in the design of the blades. The accurate and efficient calculation of aerodynamic forces (lift and drag) and the prediction of stall of an airfoil are challenging tasks. Computational fluid dynamics (CFD) is able to provide a better understanding of complex flows induced by the rotation of wind turbine blades. A numerical simulation is carried out to determine the aerodynamic characteristics of a single airfoil in a wide range of conditions. Reynolds-averaged Navier–Stokes (RANS) equations and large-eddy simulation (LES) results of flow over a single NACA0012 airfoil are presented in a wide range of AOAs from low lift through stall. Due to the symmetrical nature of airfoils, and also to reduce computational cost, the RANS simulation is performed in the 2D domain. However, the 3D domain is used for the LES calculations with periodical boundary conditions in the spanwise direction. The results obtained are verified and validated against experimental and computational data from previous works. The comparisons of LES and RANS results demonstrate that the RANS model considerably overpredicts the lift and drag of the airfoil at post-stall AOAs because the RANS model is not able to reproduce vorticity diffusion and the formation of the vortex. LES calculations offer good agreement with the experimental measurements.

Comparative analysis of low velocity vertical axis wind turbine NACA blades at different attacking angles in CFD

Blade elemental design in aerofoil in wind turbine will increase the effectiveness of power generation. Low velocity blades less than 10 m/sec considered for the design optimization in CFD. Present study is a comparison of NACA 0012, NACA4412 and used in low velocity vertical axis wind turbine. The purpose of these research was to analyse the effect on aerodynamic efficiency of the VAWT aerodynamic (maximum rotor energy coefficient) of two NACA-series 4-digit aerodynamic wings, maximum air-foil thickness and maximum camber, and the two variants in parameters on the performance. Angle of increment 0°, 5°, 10°, 15° and velocity variants input from 5, 5.5, 6, 6.5, 7, 7.5, 8 m/s. The pressure distributions at all the relevance have been observed in all the parametric variables. Aerodynamic performance analysis of all air foils with the ANSYS Fluent software was carried out. Included in different angles of approach are also the lift coefficients and drag coefficients. Optimum angles of attack were determined for each profile according to simulations. Final comparison made for both blades with optimal deviations discussed.

Effects of spreader geometry on powder spreading process in powder bed additive manufacturing

Powder spreading process is to use a spreader such as blade or roller to spread powder layers for subsequent fusion in powder bed fusion additive manufacturing. In this work, the effects of various spreader geometries on powder spreading are examined by discrete element method (DEM). The results show that a compact region in the powder pile exists. Round and inclined surfaces of blade spreaders allow more particles in the compact region to be deposited compared with vertical blades, thus the powder layer formed is denser. However, they exert larger forces on the underlying part. Inhomogeneity of powder layers is caused by particle burst phenomenon, which is due to particle motion conflict in the compact region rather than large forces. Roller system has largest particle motion conflict thus powder layers formed are sparse and inhomogeneous with small layer gaps. Size segregation in blade systems is not as severe as roller systems.

Influence of cell size effect on the vertical cutting of hexagonal thin-walled honeycombs by parallel blades

This study investigates the cutting response of AL3003H18 hexagonal honeycombs loaded with vertical array blades. Quasi-static cutting tests were performed on aluminum honeycombs of various cell sizes and the same single-walled thickness (0.04 mm) using five groups of parallel steel blades of thickness 0.24 mm. The deformation mechanism was numerically simulated in the explicit solver LS-DYNA. In addition, the cutting process was described using a theoretical model based on dimensional analysis. The cutting response of honeycombs could be divided into three stages: elastic, transitional, and stable cutting. The cutting stress was found to decrease with increasing single-walled edge (SE) length. In an empirical analysis, the cutting force equation was derived as F=1.3CNcσyt1.92d0.30l−0.22, where C is a constant, Nc is the total number of cutting points, σy is the yield strength of the matrix material, d is the cutting depth, and t and l are the thickness and length of an SE, respectively. In particular, the cutting force is proportional to the 0.30th power of the cutting depth and inversely proportional to the 0.22th power of the SE length.

Design, Fabrication and Performance Evaluation of Hybrid Vertical Axis Wind Turbine

Vertical axis wind turbines (VAWT) have attracted a lot of attention recently as an efficient tool in harnessing wind energy; however these types of wind turbine are faced with some challenges which affect their overall performance. The Darrieus rotor has difficulty to self-start by itself while the Savonius rotor has low efficiency. The performance of these turbines can be improved by combining the two VAWTs as one system. This paper presents the design of a hybrid VAWTs turbine. The Hybrid VAWTs combines the Darrieus rotor and the Savonius rotor as a single system to produce a high starting torque and enhanced efficiency. The Savonius rotor is placed at the centre of the three vertical blades of the Darrieus H-rotor to form the hybrid VAWTs. The hybrid VAWT was tested at four different wind speed i.e. V = 4.80 m/s, 4.50 m/s, 4.30 m/s and 3.90 m/s respectively. The performance of the hybrid VAWT was compared with the conventional straight bladed VAWT under similar experimental conditions. The obtained results showed that there is substantial improvement in the self-starting ability and coefficient of power (Cp). At V = 4.80 m/s, the Cp values for hybrid VAWT increased by 92% compared to straight bladed H-rotor VAWT. Similar improvement was also observed at wind speed of V = 4.50 m/s, 4.30 m/s, and 3.90 m/s where the Cp values increases by 71%, 10%, and 67% respectively compared to the straight bladed H-rotor.

Aspects Regarding the Use of 3D Printing Technology and Composite Materials for Testing and Manufacturing Vertical Axis Wind Turbines

The article presents the technology and process, whereby a small-scale demonstration model and the real-scale prototype of vertical axis wind turbine blades are produced using rapid prototyping technology (3DP) and GFRP surface coatings, which help to improve the mechanical properties. In the end of the article the results of the production process and the advantages of combining these technologies are presented.

Rancang Bangun Turbin Angin Aksis Vertikal Sebagai Alternatif Catu Daya Pada Perlintasan Sebidang Perkeretaapian

Peralatan pengaman pintu perlintasan sebidang merupakan peralatan fasilitas operasi perkeretaapian yang membutuhkan sumber energi listrik. Penggunaan bahan bakar fosil sebagai bahan bakar pembangkit listrik jumlahnya semakin menipis, menurut perkiraan jumlah cadangan bahan bakar fosil akan habis sekitar 83 tahun. Untuk menghemat cadangan bahan bakar fosil diperlukan sumber energi cadangan dari sumber energy yang terbarukan seperti energi angin. Energi angin di sekitar jalur perkeretaapian mempunyai potensi sangat besar untuk dijadikan energi listrik. Pembangit listrik mikro wind dalam penelitian ini menggunakan turbin angin dengan sudu-sudu vertikal dan pengarah angin berupa sirip. Berdasarkan hasil penelitiaan serta melakukan pengujian dapat disimpulkan bahwa turbin angin vertikal yang di implementasikan untuk pencatu peralatan pengaman pintu perlintasan dapat mengisi baterai dengan arus pengisian rata-rata 3,28 A pada kecepatan angina rata-rata 3,90 m/s dan putaran 278 rpm dan menghasilkan daya 39,45 watt dan energy total 394,5 watt sehingga dapat mengisi baterai 75Ah/12 volt selama 22 jam

Analysis of Hydrodynamic Characteristics of Ocean Ship Two-unit Vertical Axis Tidal Current Turbines with Different Arrangements

Ji, R.; Sun, K.; Wang, S.; Li, Y., and Zhang, L., 2018. Analysis of hydrodynamic characteristics of ocean ship two-unit vertical axis tidal current turbines with different arrangements. In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and OceanEngineering. Journal of Coastal Research, Special Issue No. 83, pp. 98–108. Coconut Creek (Florida), ISSN0749-0208.In order to study the hydrodynamic performance of the two-unit turbinesin different arrangements, a reasonable turbine layout plan was proposed to improve the power generation efficiency of tidal power stations. In this paper, the transient numerical simulation of a three-blade vertical-axis tidal current turbine is carried out, and the hydrodynamic performance of the turbine units with different arrangement (tandem, parallel, and staggered) is analyzed, and the influence of the mutual interference between the turbine units on the efficiency of the power generation is explored. Taking into account the same characteristics of the profile of the vertical axistidal current turbine blades along the extension, the model is simplified to two-dimensional. Firstly, based on the open source software OpenFOAM, a k-ω SST turbulence model and a PIMPLE algorithm are used for a 2D vertical axis tidal current turbine. A numerical simulation method is proposed and compared with the experimental results to verify the correctness of the numerical simulation method. Then the operation of a single turbine was simulated, and the variation of energy utilization with the tip speed ratio and the force characteristics of the turbine during operation were obtained. Finally, the vertical axis tidal turbine units with different arrangements are analyzed in detail, and the energy efficiency, force characteristics, and wake field of the vertical axis turbine units are compared and analyzed. For tandem tidal turbine units, the flow distance Dx of the two-unit turbines is used as a variable to study the effect of tidal turbine spacing on the hydrodynamic performance of downstream turbines. For parallel tidal turbines, the influence of the horizontal distance Dy and three different rotations on the hydrodynamic performance of tidal turbines is studied. For staggered turbine units, the relative distance Dr and the relative position angle ψ of the turbine are used as variables to study the relationship between the capacity of the turbine and the two parameters.

Coherent Structure of Flow Based on Denoised Signals in T-junction Ducts with Vertical Blades.

The skin friction consumes some of the energy when a train is running, and the coherent structure plays an important role in the skin friction. In this paper, we focus on the coherent structure generated near the vent of a train. The intention is to investigate the effect of the vent on the generation of coherent structures. The ventilation system of a high-speed train is reasonably simplified as a T-junction duct with vertical blades. The velocity signal of the cross duct was measured in three different sections (upstream, mid-center and downstream), and then the coherent structure of the denoised signals was analyzed by continuous wavelet transform (CWT). The analysis indicates that the coherent structure frequencies become abundant and the energy peak decreases with the increase of the velocity ratio. As a result, we conclude that a higher velocity ratio is preferable to reduce the skin friction of the train. Besides, with the increase of velocity ratio, the dimensionless frequency St of the high-energy coherent structure does not change obviously and St = 3.09 × 10−4–4.51 × 10−4.

Aerodynamics and Modal Analysis for the Combined Vane type Vertical Axis Wind Turbine

The present global energy economy suggests the use of renewable sources such as solar, wind, and biomass to produce the required power. The vertical axis wind turbine is one of wind power applications. Usually, when the vertical axis wind turbine blades are designed from the airfoil, the starting torque problem begins. The main objective of this research is to numerically simulate the combination of movable vanes of a flat plate with the airfoil in a single blade configuration to solve the starting torque problem. CFD analysis in ANSYS-FLUENT and structural analysis in ANSYS of combined blade vertical axis wind turbine rotor has been undertaken. The first simulation is carried out to investigations the aerodynamic characteristic of the turbine by using the finite volume method. While the second simulation is carried out with finite element method for the modal analysis to find the natural frequencies and the mode shape in order to avoid extreme vibration and turbine failure, the natural frequencies, and their corresponding mode shapes are studied and the results were presented with damping and without damping for four selected cases. The predicted results show that the static pressure drop across the blade increase in the active blade side because of the vanes are fully closed and decrease in the negative side because of the all the vanes are fully open. The combined blade helps to increase turbine rotation and so, thus, the power of the turbine increases. While the modal results show that until the 5th natural frequency the effect of damping can be neglected. The predicted results show agreement with those reported in the literature for VAWT with different blade designs.

Preliminary Test on Cross Axis Type Wind Turbine

The dependence on fossil fuel for power generation has a significant negative impact on environmental damage. To reduce the environmental damage, the use of wind energy for power generation needs to be increased and improved. A new type of wind turbine which has been reported recently is a cross axis wind turbine which can be designed for use in high-rise urban buildings where wind condition is more favorable. A model of a cross axis wind turbine which has a rotor diameter of 70 cm and a height of 60 cm has been fabricated and preliminarily tested. The wind turbine model consists of five vertical blades and two horizontal blade arrangements each having five blades. The performance test was carried out at a constant wind speed. During the test, the blade pitch angle was varied from 20 to 60 and wind speed was varied from 5 m/s to 7 m/s. Analysis and evaluation results show that the output power and efficiency of the wind turbine are affected by the blade pitch angle. At wind speed of about 7 m/s, the estimated maximum power is 0.15 W and maximum efficiency of only 0.17% for which the pitch angle was about 60 and tip speed ratio about 0.35.

Experimental and numerical study of natural ventilation in four-sided wind tower traps

In the past, wind towers were applied as the main architectural part of building construction in the desert areas of Iran. These almost high structures were used as cooling load suppliers at residential buildings. In the present study, the effect of symmetric four-sided wind tower in flow induction to the bottom space has been analysed by using a wind tunnel and numerical simulations. In the numerical simulation, the flow is assumed to be three-dimensional, unsteady, compressible and turbulent. The experimental studies have been performed by placing a model of these structures at a laboratory wind tunnel. At this state, crossing airflow through every channel is measured for analysing the induction performance of wind tower at different angles of wind blowing. Moreover, the turbulence effect is analysed by adding horizontal and vertical blades and crowns at the top and bottom of the internal gate of traps for attaining better performance. Two different geometries are used for simulations. The results showed that inserting the blade and crown at the bottom and topaffect on the flow rate have effect on the flow rate. For instance, inserting horizontal blades and crown at the top of the model leads to 8 and 16% increase in the flow rate, respectively. The results of the numerical simulations have shown acceptable agreement with experimental results.

Dynamic stall in vertical axis wind turbines: scaling and topological considerations

Vertical axis wind turbine blades are subject to rapid, cyclical variations in angle of attack and relative airspeed which can induce dynamic stall. This phenomenon poses an obstacle to the greater implementation of vertical axis wind turbines because dynamic stall can reduce turbine efficiency and induce structural vibrations and noise. This study seeks to provide a more comprehensive description of dynamic stall in vertical axis wind turbines, with an emphasis on understanding its parametric dependence and scaling behaviour. This problem is of practical relevance to vertical axis wind turbine design but the inherent coupling of the pitching and velocity scales in the blade kinematics makes this problem of more broad fundamental interest as well. Experiments are performed using particle image velocimetry in the vicinity of the blades of a straight-bladed gyromill-type vertical axis wind turbine at blade Reynolds numbers of between 50 000 and 140 000, tip speed ratios between $\unicode[STIX]{x1D706}=1$ to $\unicode[STIX]{x1D706}=5$, and dimensionless pitch rates of $0.10\leqslant K_{c}\leqslant 0.20$. The effect of these factors on the evolution, strength and timing of vortex shedding from the turbine blades is determined. It is found that tip speed ratio alone is insufficient to describe the circulation production and vortex shedding behaviour from vertical axis wind turbine blades, and a scaling incorporating the dimensionless pitch rate is proposed.

Two-dimensional fluid–structure interaction analysis of a vertical axis tidal turbine blade using periodic inflow equivalence model

Fluid structure response of vertical axis tidal turbine blades using NACA 0012 and periodic inflow equivalence model are predicted in this work. The response is investigated numerically by developi...

Assessment of the numerical and experimental performance of screw tidal turbines

This study was aimed at the numerical and experimental modeling of water flow during collision between water and vertical screw turbine blades with different cross sections (i.e. Darrieus, spoon, and airfoil). ANSYS Fluent was used to model water flow under tidal currents in a flume, and mesh independence was ensured after the selection of appropriate geometry. The collision problem was then solved in the transient state, and results on the momentum and power generated by different inlet velocities and different blade cross sections were analyzed. The findings showed that torque and turbine power increased with increasing inlet velocity. Subsequently, a turbine was experimentally created, with cross sections drawn in the numerical model and tested under the same conditions as that imposed on the model. Installing a multimeter on the turbine enabled the generation of turbine power in different dimensions. The resultant power increased with rising turbine dimensions. After obtaining the numerical and experimental results, the value of the output power of the turbine was validated. The validation indicated a 7% difference in output power between the numerical and experimental results, indicating acceptable accuracy.

Influence on Flow Field with Aerodynamic Interaction between Vertical Axis Hybrid Turbine Blades

Influence on Flow Field with Aerodynamic Interaction between Vertical Axis Hybrid Turbine Blades

Interceptor design for optimum trim control and minimum resistance of planing boats

Interceptors are vertical blades installed symmetrically aft of the craft. This article aims to investigate the main geometrical (height and span length) parameters in interceptors. Different Models with and without interceptors at different heights and spans have been analyzed based on the finite volume method and SIMPLE algorithm using dynamic mesh. In order to validate CFD results, the grid convergence index (GCI method) has been used to estimate the uncertainties caused by grid-spacing and time-step. Although it has been proved that the interceptors are very useful in trim control and resistance reduction, choosing wrong size interceptors could not only destroy their effectiveness, but also endanger the planing boat due to the creation of a strong moment leading to negative trim. The results of this study show that among all effective variables, the boundary layer thickness (h) at the stern (where the interceptor is installed), is far more important than, some other particular parameter, on interceptor performance and should be taken into account in estimating the interceptor height (d) and span (s). Generally, the interceptor height should not be higher than 60 percent of boundary layer thickness at transom. For optimum efficiency, when the interceptor height equals 60 percent of the boundary layer, the interceptor span length should be seven times as much as the interceptor height. At the end, based on Reynolds number the paper presents three figures, setting the basis for optimal interceptor sizes for its use in planing boats.