Conventional Vertical Axis Wind Turbine Research Articles

Improvement of vertical axis wind turbine performance by using the optimized adaptive flap by the Taguchi method

ABSTRACT In light of the growing use of Vertical Axis Wind Turbines (VAWTs) in urban settings, research is increasingly focusing on passive control methods to enhance VAWT efficiency. This study aims to refine VAWT performance by optimizing an advanced turbine design equipped with an adaptive flap on the blade, focus on the power coefficient (CP). Using the Taguchi method, the optimization incorporated five control factors: flap position (ld), flap length (lf), flap angle (θ), flap tip length (lt), and angle of the flap tip length (αtip). The study employed an L16 (54) orthogonal array design. At a 2.62 tip speed ratio (TSR), all models underwent computational fluid dynamics (CFD) simulation. The influence of each factor was assessed using the ANOVA (Analysis of variance), and CP predictions were made based on these factors through Regression Analysis (RA). The results revealed optimal configurations of ld = 0.65c, lf = 0.15c, θ = 70°, lt = 0.06c, and αtip = 8, leading to a CP 74.01% greater than a conventional VAWT. ANOVA ranked factor contributions as: ld > lt > θ > lf > αtip, with ld contributing 39.58% and αtip only 1.34%. Predictions from the RA aligned well with the numerical findings. In conclusion, the adaptive flap design enhances performance by expanding the wake and amplifying the vortices behind the turbine blade.

Development and verification of a dynamic analysis model for floating offshore contra-rotating vertical-axis wind turbine

Vertical axis wind turbines (VAWT) have a lower center of mass because the mechanical systems are placed at the bottom of the tower. This leads to more stable motions in the offshore environment However, the effect of torque leads to continuous loading of the tower, constant platform motions, and increased mooring tension. For this reason, a contra-rotating VAWT is adopted to mitigate the structural loads and platform motions induced by the counterbalanced torque produced by the two rotors. Initially we developed and validated an integrated analysis tool for floating VAWTs and extended to account for the contra-rotating rotor. Finally, the loads and motions of the contra-rotating VAWT are assessed using the developed tool. The results indicated that the contra-rotating VAWT had better structural loads and, in case of the floating model, the platform motions were smaller, and the mooring tension was lower. A land-based contra-rotating VAWT with blade length and rotor radius greater than 48.5 m and 54 m can achieve better performance compared to conventional VAWT with 80 m and 39 m respectively. Consequently, notwithstanding the reduced aerodynamic power, the decreased structural responses of the contra-rotating VAWT imply that its fatigue loads, would be lower compared to those of the conventional VAWT.

An investigation on the aerodynamic performance of a co-axial contra-rotating vertical-axis wind turbine

In this study, a conceptual co-axial contra-rotating vertical axis wind turbine (CR-VAWT) is conceived by splitting the single conventional vertical axis wind turbine (C-VAWT) blade length into two equal lengths forming two rotors separated by a small distance about the same axis of rotation. The available literature lacks much systematic investigation to find the best possible numerical setting and to extract an in-depth understanding of dominant factors limiting the aerodynamic performance of the CR-VAWT using CFD, constitutes the primary focus for the present study. Results from the CFD were compared with the analytical model formulated using FAST along with literature results. The power output of the CR-VAWT agrees well in the low wind speed and variation increases gradually as the wind speed increases compared to C-VAWT, however, the thrust is in good agreement at all wind speeds. The wake velocity directly behind the C-VAWT and CR-VAWT follows the general trend but differences were noticed to a distance accordingly, with the wind speed. The power performance reduces gradually with increasing speed for a fixed blade pitch angle. The present adopted concept of CR-VAWT are found to have negligible aerodynamic torque and side-side force action at the tower base.

Power coefficient measurements of a novel vertical axis wind turbine

AbstractWind tunnel experiments were performed to evaluate the power coefficients of three vertical axis wind turbines (VAWTs), namely, (a) conventional VAWT (two‐bladed troposkien shape), (b) novel 50% shifted troposkien shape‐vertical axis wind turbine (50% STS‐VAWT), and (c) novel 100% STS‐VAWT. All turbines had the same height, swept area, and NACA0015 airfoil with the same chord length. During the power coefficient measurements for each one of the turbines, the wind tunnel velocity was varied while the turbine rotation was kept constant through rheostatic load adjustment. Two different turbine rotations were used (600 rpm and 700 rpm). The resulting tip speed ratios (TSRs) ranged from approximately 2 to 6 in the current investigation. Both the power coefficients and the tip speed ratios were corrected against wind tunnel blockage effects. The 50% STS‐VAWT model showed an overall better aerodynamic performance (both corrected and uncorrected power coefficients) when compared against the other two configurations, likely due to a combination of (a) power generation increased due to blade‐wake interaction (BWI) reductions and (b) power generation capacity related to the blade length of each turbine.

Numerical investigations of a novel vertical axis wind turbine using Blade Element Theory‐Vortex Filament Method (BET‐VFM)

AbstractThe aerodynamic performance of three different configurations of vertical axis wind turbines (VAWT), namely: (a) conventional Darrieus troposkein VAWT (based on turbines designed by Sandia National Laboratories), (b) novel 50% STS‐VAWT (50% shifted‐troposkein‐shaped STS‐VAWT), and (c) novel 100% STS‐VAWT were investigated numerically. An in‐house code, which combined the blade element theory (BET) and the vortex filament method (VFM), was used. The main purpose of this work was to develop an aerodynamic code to predict the performance of conventional VAWT as well as assess the novel 50% and 100% STS‐VAWT configurations. Simulation results (power coefficients) were verified and then validated against experimental data available from the literature (2‐, 5‐, and 17‐m conventional troposkein VAWT measured by Sandia National Laboratories). Additional numerical results showed that the 50% STS‐VAWT outperformed both the conventional VAWT and the 100% STS‐VAWT by up to 14% (peak power), within the range of rotation and turbine sizes that were investigated in the present work.

Performance analysis of the deflector integrated cross axis wind turbine

Wind turbines in the context of integration in an urban environment are considered as one of the most promising technologies for the efficient diffusion of renewable energy sources. However, situations such as low wind velocity, highly turbulent and skewed wind flow conditions are commonly encountered in this environment. This misaligned flow could affect the horizontal axis wind turbine performance. The vertical axis wind turbine (VAWT) is more suitable to operate under these unfavorable conditions. Nevertheless, the conventional VAWT has low efficiency and poor self-starting characteristics. Therefore, a novel design of deflector integrated cross axis wind turbine (CAWT) is proposed. Tests were carried out to harness wind energy from both the horizontal and vertical components of the skewed flow induced by the deflectors. A semi-empirical approach was also developed to analyse the performance of the CAWT. The aerodynamic behaviour of the CAWT was determined by combining the blade element momentum (BEM) model and double multiple streamtube theory (DMST). The approach showed notable agreement between the experimental and theoretical results (9.8%–14.2% difference). In conclusion, the findings from the experiment and the model showed that the concept has very good potential in the renewable energy industry.

Optimization of 300 Watt Vertical Axis Wind Turbine for Low Wind Speed Regions: A Case Study of Malaysia

This study demonstrates the overall performance and efficiency of a 300 Watt conventional vertical axis wind turbine manufactured by (i-wind) for a low wind speed regions. The study investigates the increasing of blade tangential velocity by adding a new blade attached to the main blade of the turbine. The new blades called secondary blades which will take the effect of increasing the tangential velocity and hence increasing the rated output power. The new contribution proposed in this study was taken into considerations the optimum position of the secondary blades. The position was taken to be in parallel location with the main blades under different configurations and distances (7, 10, 15 and 20 cm). A simulation analysis using ANSYS CFD was proposed in this study to evaluate the tangential velocity and the rotational speed of different cases for the modified vertical axis wind turbine. The range of wind velocities were 5 to 12 m/s in order to cover a reasonable range of wind speed. The variation of power and rotational speed was compared with the power and rotational speed calculated for the conventional wind turbine. The study illustrates the correlations of power and rotational speed of the modified vertical axis wind turbine. The increasing of tangential velocity and output power for the modified turbine under a minimum wind speed of 5 m/s were found to be 17% and 51% respectively.

수직축 풍력터빈의 날개 형상에 따른 성능비교

Vertical Axis Wind Turbine (VAWT) has advantages including simpler structure and significantly cheaper cost to build and maintain than the conventional Horizontal Axis Wind Turbine (HAWT), attract the most of worlds attention. However, such rotor is suffering from poor efficiency problems. The present study will consider the design improvement of a VAWT that employs a multi-blade design using both rectangular guide vanes and rotor blades arrays. As a result, an optimum formation of guide vanes as well as rotor blades needs to be found in order to enhance the power performance. The study used CFD code to obtain the flow field characteristics for purpose of evaluating the turbine performance with guide vanes and rotor blades in different shapes, at different tip speed ratio (TSR) values. From the simulation results, it was shown that the performance is apparently improved than Conventional VAWT.

POWER GENERATION USING MAGLEV WINDMILL

The paper project describes the implementation of different type of a wind turbine for purpose of power generation. A vertical axis wind turbine (VAWT) with use of magnetic levitation technology for optimal performance of wind turbine has been discussed. With the merits of conventional VAWT, the merits of starting at low wind-speed, higher efficiency, low noise emission, etc. are also discussed. The major consequence in front of conventional wind turbine is loss of energy during rotation. By using nature of permanent magnet as a perfect replacement for ball bearings levitation of the turbine is intended thus reducing energy losses while rotation. Using this effect wind turbine blades are placed on a rod for obtaining stability during rotation. Power is then generated by using an axial flux generator, which has incorporated the utilization of permanent magnets and a set of coils.

Design optimisation of an offshore vertical axis wind turbine

Horizontal axis wind turbines have a number of limitations for offshore operations, particularly in deep water (i.e. over 50 m). For example, scalability restrictions, the necessity for high lift installations offshore requiring specialist vessels, high gravitational and aerodynamic moments on the support structure and a need to maintain rotary equipment at heights typically over 60–80 m. Conversely, vertical axis wind turbines have several inherent attributes that offer some advantages for offshore operations, particularly their scalability and low over-turning moments with better accessibility to drivetrain components. This paper describes the aerodynamic optimisation of a novel 10 MW vertical axis wind turbine rotor shape offering a low-stress design to minimise manufacturing and maintenance costs of the whole turbine assembly including the supporting structure and foundations. The Aerogenerator vertical axis wind turbine is self-supporting so does not require a supporting tower, giving a low centre of gravity and producing significantly lower aerodynamic over-turning moments than conventional vertical axis wind turbines or horizontal axis wind turbines, making it a credible option for a floating, deep water platform. A numerical optimisation procedure is described to minimise the Aerogenerator weight while imposing aerodynamic, mechanical and structural side constraints. The study proposes a novel ‘sycamore’-shaped rotor design that demonstrates a lower cost of energy compared with conventional offshore turbines.

Computational Study to Assess the Influence of Overlap Ratio on Static Torque Characteristics of a Vertical Axis Wind Turbine

Abstract This paper presents an unsteady two-dimensional computational study in order to observe the effect of overlap ratios on static torque characteristics of a vertical axis wind turbine (VAWT). The study is performed with the help of a finite volume based computational fluid dynamics (CFD) software package Fluent 6.3. The computational model is a two-bladed conventional VAWT having overlap ratios of 0, 0.10, 0.15, 0.20, 0.25 and 0.30. Initially, a comparative analysis is made using various k turbulence models and then the results are compared with the experimental data available in literature. A realizable k turbulence model with enhanced wall treatment is found suitable for further computational analysis. The flow field around the turbine model is also studied with the help of static pressure contour analysis. Based on this computational study, it is realized that an overlap ratio of 0.20 eliminates the effects of negative static torque coefficient, provides a low static torque variation at different turbine angular positions and also gives a higher mean static torque coefficient as compared to the other overlap ratios.