Query: Horizontal axis wind turbine a winglet 2020

title: PERFORMANCE OF HORIZONTAL AXIS WIND TURBINE WITH CONICAL WINGLET
abstract: The wind flowing through a diffuser augmented wind turbine travels along the walls of the diffuser causes in the exiting wind to form vortices of wind when exiting and these vortices cause most of the air to be diffused away from the centre of the exit, which creates a low pressure segment of air behind the turbine which accelerates the high pressure air in the front towards the low pressure air in the back, causing a significant increase in rotor speed. A three bladed horizontal axis wind turbine with a diffuser surrounding the blades is considered in the present study to investigate the power enhancement achieved. The wind turbine power output, efficiency with and without augmenting ring is estimated at rotor speeds varying from 0.5 to 2 Rad/sec at wind speeds ranging from 8 to 24 m/s using Ansys 18.1 CFX software. It is observed that at all rotational speeds, the effect of diffuser is less at higher wind velocities (beyond 16 to 18 m/sec) and maximum power augmentation at all rotor speeds is realized only at 16 to 18m/sec. For turbines installed on land, the average wind velocity in India ranges from 20 to 40 km/hour (6 to 12 m/sec) and hence using diffuser would be definitely an added advantage without additional investment cost. The power coefficient showed rapidly decreasing trend with increasing wind speed and attains very low values at speeds greater than 20 m/sec. At 8 meters/sec the coefficient exceeded Betz limit of 0.59 at 1. rad/sec and hence running turbine at speed beyond 1 rad/sec is not feasible. With regard to thrust coefficient It is seen that the trend of decreasing value with increasing wind speed is similar to power coefficient and also lower values of both coefficients are realized for lower rotor speeds. It is also noticed from literature that this trend is similar to the other similar wind turbines. Further all the thrust coefficient values for turbine with diffuser indicated more or less same increase for all rotor speeds (20% for 12 m/sec at 2 rad/sec and 18% 12 m/sec at 0.5 rad/sec)

title: Aerodynamic Investigation of a Horizontal Axis Wind Turbine with Split Winglet Using Computational Fluid Dynamics
abstract: Wind energy is one of the fastest growing renewable energy sources, and the most developed energy extraction device that harnesses this energy is the Horizontal Axis Wind Turbine (HAWT) Increasing the efficiency of HAWTs is one important topic in current research with multiple aspects to look at such as blade design and rotor array optimization. This study looked at the effect of wingtip devices, a split winglet, in particular, to reduce the drag induced by the wind vortices at the blade tip, hence increasing performance. Split winglet implementation was done using computational fluid dynamics (CFD) on the National Renewable Energy Lab (NREL) Phase VI sequence H. In total, there are four (4) blade configurations that are simulated, the base NREL Phase VI sequence H blade, an extended version of the previous blade to equalize length of the blades, the base blade with a winglet and the base blade with split winglet. Results at wind speeds of 7 m/s to 15 m/s show that adding a winglet increased the power generation, on an average, by 1.23% whereas adding a split winglet increased it by 2.53% in comparison to the extended blade. The study also shows that the increase is achieved by reducing the drag at the blade tip and because of the fact that the winglet and split winglet generating lift themselves. This, however, comes at a cost, i.e. an increase in thrust of 0.83% and 2.05% for the blades with winglet and split winglet, respectively, in comparison to the extended blade.

title: Effect of winglet geometry on horizontal axis wind turbine performance

title: Investigation of an Innovative Rotor Modification for a Small Scale Horizontal Axis Wind Turbine
abstract: This paper presents the results of the computational fluid dynamics (CFD) simulation of the airflow for a 300 W horizontal axis wind turbine, using additional structural elements which modify the original shape of the rotor in the form of multi shaped bowls which change the airflow distribution. A three dimensional CAD model of the tested wind turbine was presented, with three variants subjected to simulation: a basic wind turbine without the element that modifies the airflow distribution, a turbine with a plano convex bowl, and a turbine with a centrally convex bowl, with the hyperbolic disappearance of convexity as the radius of the rotor increases. The momentary value of wind speed, recorded at measuring points located in the plane of wind turbine blades, demonstrated an increase when compared to the base model by 35% for the wind turbine with the plano convex bowl, for the wind speed of 5 m/s, and 31.3% and 49% for the higher approaching wind speed, for the plano convex bowl and centrally convex bowl, respectively. The centrally convex bowl seems to be more appropriate for higher approaching wind speeds. An increase in wind turbine efficiency, described by the power coefficient, for solutions with aerodynamic bowls was observed.

title: Design of small horizontal axis wind turbine for low wind speed rural applications
abstract: In this study, a 2 kW small scale horizontal axis wind turbine with rotor radius of 1.8 m and Tip Speed Ratio of 6 was designed to work at low wind speed for rural applications. Aerodynamic analysis was performed on 10 airfoils, viz Aquila, BW 3, E387, FX63 137, NACA0012, NASA LS 0413, RG 15, S1223, SD7080 and SG6043 using QBlade software. These airfoils were used to analyze Lift Coefficient, Lift to Drag ratio, with different angles of attack and compared with one another. From Numerical simulation, SD7080 was the most suitable airfoil to start producing high power in low wind speed applications.

title: Analytical Assessment of the Effects of Blade Cone Angle on the Aerodynamic Performance of the Horizontal Axis Wind Turbine
abstract: In this research, the performance of a horizontal axis wind turbine (HAWT) is investigated, considering the cone angle effects. In a HAWT with an ordinary pattern, all blades are located in one plate and the cone angle of the plate is zero. In the design of HAWTs, to prevent contact between the blades and the turbine's tower and considering the aero elasticity effects, the blades are installed on the shaft of the rotor using a cone angle, which has effects on the turbine's performance. We investigated the aerodynamic performance of the HAWT according to cone angle deviations, numerically. With a change in the blade's plate pattern, a cone shaped volume is created. In this condition, the projected blade's length gets smaller and the blade's sections (vertical to the wind) become larger. The geometry of these sections was obtained with AutoCAD software. The performance of the turbine was analysed with Qblade software, and the results compared with each other. The output results of Qblade for the situation, in which the cone angle is considered, equal to the projected blade's length and the new sections for the projected airfoils within the zero cone angle investigated and compared. This research was carried out for two conditions: a blade with a constant chord and a blade with different chords through the length of the blade. The creation of the cone angle may be suggested as one approach for controlling the wind turbine.

title: Performance analysis of a small horizontal axis wind turbine under the use of linear/nonlinear distributions for the chord and twist angle
abstract: The increase in efficiency, decrease in starting time, and ease in manufacturing of rotor blades are the most desirable aims of research in the design of small scale wind turbines. A multi objective optimization study is carried out to analyze the performance of a small horizontal axis wind turbine in terms of the output power and the starting time for four possible combinations of linear/nonlinear distributions of the chord length and twist angle along one meter timber blades. The blade element momentum theory is adopted for the calculation of the power coefficient and the starting time. The optimization is achieved through a genetic algorithm which simultaneously maximized the power coefficient and minimized the starting time. The most important contribution of this paper is the in depth comparison of the linear and the nonlinear distributions for chord and twist angle subjected to the aforementioned optimization, which is not available in the existing literature in such detail. Results show that although the linear distributions have more deviation from the so called ideal distributions, however, the output power performance of the blades with linear distributions is competitive with that of the nonlinear ones. Moreover, the results establish that the use of linear distribution can improve the starting performance at a lesser compromise of output power. This is of paramount importance, particularly to promote harnessing the wind energy in developing countries, as simpler distributions could facilitate the manufacturing of wind turbine blades. Apart from using the linear or nonlinear distributions for both the chord and the twist angle, two other cases are also investigated including the linear distribution for the chord and the nonlinear one for the twist and vice versa. The analysis of these cases shows that choosing the nonlinear distribution for the chord would improve the starting while using the linear one would lead to more powerful blades.

title: Effects of Dimples on Aerodynamic Performance of Horizontal Axis Wind Turbine Blades
abstract: aM.Sc.  Engineering Department, Adama Science and Technology University, Adama, Ethiopia bAssistant Professor, Mechanical Engineering Department, Adama Science and Technology University, Adama, Ethiopia cLecturer, Mechanical Engineering Department, Adama Science and Technology University, Adama, Ethiopia Abstract Wind energy is one of the fast growing power industry and promising renewable energy source in the world. Wind turbine technology is a system that converts kinetic energy of the wind into electrical energy. The main purpose of this study is to investigate the aerodynamic effect of dimples over the surface of a horizontal axis wind turbine (HAWT) blades.

title: Computational Fluid Dynamics Analysis of Multi Bladed Horizontal Axis Wind Turbine Rotor
abstract: The principal objective of this work was to investigate the 3D flow field around a multi bladed horizontal axis wind turbine (HAWT) rotor and to investigate its performance characteristics. The aerodynamic performance of this novel rotor design was evaluated by means of a Computational Fluid Dynamics commercial package. The Reynolds Averaged Navier Stokes (RANS) equations were selected to model the physics of the incompressible Newtonian fluid around the blades. The Shear Stress Transport (SST) k o turbulence model was chosen for the assessment of the 3D flow behavior as it had widely used in other HAWT studies. The pressure based simulation was done on a model representing one ninth of the rotor using a 40 degree periodicity in a single moving reference frame system. Analyzing the wake flow behavior over a wide range of wind speeds provided a clear vision of this novel rotor configuration. From the analysis, it was determined that the flow becomes accelerated in outer wake region downstream of the rotor and by placing a multi bladed rotor with a larger diameter behind the forward rotor resulted in an acceleration of this wake flow which resulted in an increase the overall power output of the wind machine.

title: Performance Analysis of Horizontal Axis Wind Turbine using Variable Blade Pitch Control Mechanism
abstract: This work investigates the performance of a horizontal axis wind turbine (HAWT) with variable blade pitch control mechanism. The control mechanism is a simple mechanical Watt governor design, which was developed to regulate the blade pitch angle of the HAWT depending on wind speed magnitude. The HAWT model with the control mechanism was tested for performance in a wind tunnel. Response of the control mechanism in terms of blade pitch angle, rotor speed and generator power output were analyzed based on regulated predetermined wind speeds. The result shows a gradual increase in rotor speed and a proportional increase in generator power output between cut in wind speed of 2.5m/s and rated wind speed of 6 m/s. These parameters were kept constant at 100 RPM and 50 Watts as observed due to the steady response of the control mechanism. The steadiness lasted up to a cut out wind speed of 9 m/s. The control mechanism subsequently shutdown the turbine at the cut out wind speed to protect the turbine against wind speeds higher than 9 m/s. The performance test predicts that the variable blade pitch control mechanism was able to regulate and bring about the require control of HAWT model. The mechanism allows the turbine to only operate between 2.5 and 9 m/s at blade pitch angle between 82 and 90 degrees from the axis of wind flow and change in governor height between 0 to 8 mm.