Yawed Effect on Wind Turbine Near Wake

2014 ◽  
Author(s):  
Yuntian Ge ◽  
Xiuling Wang
Keyword(s):  
Wind Turbine ◽  
Flow Pattern ◽  
Wind Turbines ◽  
Air Flow ◽  
Aerodynamic Performance ◽  
Wake Flow ◽  
Near Wake ◽  
Rotation Plane ◽  
The Difference ◽  
Ansys Workbench

Wind turbines rotation was motivated by the force of wind. In reality, wind doesn’t moving vertically to the wind turbine rotation plane, but in random directions instead. Therefore, the yawed effect has to be taken into consideration when study wind turbine aerodynamic performance. The purpose of this study is to compare the difference between the wind turbine near wake flow with yawed effect and without yawed effect aerodynamically. The research uses CFD technology to simulate the rotation movement and air flow pattern, which is completed in software Ansys Workbench.

scholarly journals Investigation into Yaw Motion Influence of Horizontal-Axis Wind Turbine on Wake Flow Using LBM-LES

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5248
Author(s):  
Weimin Wu ◽  
Xiongfei Liu ◽  
Jingcheng Liu ◽  
Shunpeng Zeng ◽  
Chuande Zhou ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Aerodynamic Characteristics ◽  
Angular Speed ◽  
Aerodynamic Performance ◽  
Tip Vortex ◽  
Wake Flow ◽  
Horizontal Axis Wind Turbine ◽  
Near Wake ◽  
Eddy Simulation ◽  
Sweep Surface

The dynamic yaw motion of the wind turbine will affect the overall aerodynamic performance of the impeller and the corresponding wake flow, but the current research on this issue is inadequate. Thus, it is very necessary to study the complicated near-wake aerodynamic behaviors during the yaw process and the closely related blade aerodynamic characteristics. This work utilized the multi-relaxation time lattice Boltzmann (MRT-LBM) model to investigate the integral aerodynamic performance characteristics of the specified impeller and the dynamic changes in the near wake under a sine yawing process, in which the normalized result is adopted to facilitate data comparison and understanding. Moreover, considering the complexity of the wake flows, the large eddy simulation (LES) and wall-adapting local eddy-viscosity (WALE) model are also used in this investigation. The related results indicate that the degree of stability of tip spiral wake in the dynamic yaw condition is inversely related to the absolute value of the change rate of yaw angular speed. When the wind turbine returns to the position with the yaw angle of 0 (deg) around, the linearized migration of tip vortex is changed, and the speed loss in the wake center is reduced at about the normalized velocity of 0.27, and another transverse expansion appeared. The directional inducing downstream of the impeller sweep surface for tip vortex is clearly reflected on the entering side and the exiting side. Additionally, the features of the static pressure on the blade surface and the overall aerodynamic effects of the impeller are also discussed, respectively.

A Comparative Study of the Wind Loads and Wake Characteristics of a Single-Rotor Wind Turbine and Dual-Rotor Wind Turbines

2014 ◽  
Author(s):  
Ahmet Ozbay ◽  
Wei Tian ◽  
Hui Hu
Keyword(s):  
Turbulent Flow ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Wind Farm ◽  
Wake Flow ◽  
Wind Loads ◽  
Neutral Stability ◽  
Near Wake ◽  
Wake Characteristics

An experimental study was carried out to investigate the aeromechanics and wake characteristics of dual-rotor wind turbines (DRWTs) with co- and counter-rotating configurations, in comparison to those of a conventional singlerotor wind turbine (SRWT), in order to elucidate the underlying physics to explore/optimize design of wind turbines for higher power yield and better durability. The experiments were performed in a large-scale Aerodynamic/Atmospheric Boundary Layer (AABL) wind tunnel under neutral stability conditions. In addition to measuring the power output performance of DRWT and SRWT systems, static and dynamic wind loads acting on those systems were also investigated. Furthermore, a high resolution PIV system was used for detailed near wake flow field measurements (free-run and phase-locked) so as to quantify the near wake turbulent flow structures and observe the transient behavior of the unsteady vortex structures in the wake of DRWT and SRWT systems. In the light of the promising experimental results on DRWTs, this study can be extended further to investigate the turbulent flow in the far wake of DRWTs and utilize multiple DRWTs in different wind farm operations.

EXPERIMENTAL AND ANALYTICAL STUDIES OF VERTICAL AXIS WIND TURBINES

2018 ◽  
pp. 51-58
Author(s):  
B. P. Khozyainov
Keyword(s):  
Wind Turbine ◽  
Flow Velocity ◽  
Wind Power ◽  
Wind Turbines ◽  
Power Efficiency ◽  
Air Flow ◽  
Geometrical Parameters ◽  
Wind Speeds ◽  
Analytical Studies ◽  
Air Flow Velocity

The article carries out the experimental and analytical studies of three-blade wind power installation and gives the technique for measurements of angular rate of wind turbine rotation depending on the wind speeds, the rotating moment and its power. We have made the comparison of the calculation results according to the formulas offered with the indicators of the wind turbine tests executed in natural conditions. The tests were carried out at wind speeds from 0.709 m/s to 6.427 m/s. The wind power efficiency (WPE) for ideal traditional installation is known to be 0.45. According to the analytical calculations, wind power efficiency of the wind turbine with 3-bladed and 6 wind guide screens at wind speedsfrom 0.709 to 6.427 is equal to 0.317, and in the range of speed from 0.709 to 4.5 m/s – 0.351, but the experimental coefficient is much higher. The analysis of WPE variations shows that the work with the wind guide screens at insignificant average air flow velocity during the set period of time appears to be more effective, than the work without them. If the air flow velocity increases, the wind power efficiency gradually decreases. Such a good fit between experimental data and analytical calculations is confirmed by comparison of F-test design criterion with its tabular values. In the design of wind turbines, it allows determining the wind turbine power, setting the geometrical parameters and mass of all details for their efficient performance.

Near-Wake Flow Simulations for a Mid-Sized Rim Driven Wind Turbine

2013 ◽  
Author(s):  
Bryan Kaiser ◽  
Svetlana Poroseva ◽  
Erick L. Johnson ◽  
Rob Hovsapian
Keyword(s):  
Wind Turbine ◽  
Wake Flow ◽  
Near Wake ◽  
Flow Simulations

Experimental Investigation on the Tip Vortex of a Wind Turbine With and Without a Slotted Tip

2017 ◽  
Author(s):  
Pengyin Liu ◽  
Jinge Chen ◽  
Shen Xin ◽  
Xiaocheng Zhu ◽  
Zhaohui Du
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Wind Turbine ◽  
Vortex Core ◽  
Control Method ◽  
Tip Vortex ◽  
Wake Flow ◽  
Core Model ◽  
Near Wake ◽  
Measured Velocity

In this paper, a slotted tip structure is experimentally analyzed. A wind turbine with three blades, of which the radius is 301.74mm, is investigated by the PIV method. Each wind turbine blade is formed with a slots system comprising four internal tube members embedded in the blade. The inlets of the internal tube member are located at the leading edge of the blade and form an inlet array. The outlets are located at the blade tip face and form an outlet array. The near wake flow field of the wind turbine with slotted tip and without slotted tip are both measured. Velocity field of near wake region and clear images of the tip vortex are captured under different wake ages. The experimental results show that the radius of the tip vortex core is enlarged by the slotted tip at any wake age compared with that of original wind turbine. Moreover, the diffusion process of the tip vortex is accelerated by the slotted tip which lead to the disappearance of the tip vortex occurs at smaller wake age. The strength of the tip vortex is also reduced indicating that the flow field in the near wake of wind turbine is improved. The experimental data are further analyzed with the vortex core model to reveal the flow mechanism of this kind of flow control method. The turbulence coefficient of the vortex core model for wind turbine is obtained from the experimental data of the wind turbine with and without slotted tip. It shows that the slotted tip increases the turbulence strength in the tip vortex core by importing airflow into the tip vortex core during its initial generation stage, which leads to the reduction of the tip vortex strength. Therefore, it is promising that the slotted tip can be used to weaken the vorticity and accelerate the diffusion of the tip vortex which would improve the problem caused by the tip vortex.

Investigations of Unsteady Aerodynamics of an Offshore Floating Wind Turbine With Platform Motions Using Dual-Sliding Method

2020 ◽  
Author(s):  
Xiaodong Wang ◽  
Zhaoliang Ye ◽  
Ziwen Chen ◽  
Yize Guo ◽  
Yujun Qiao
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Aerodynamic Performance ◽  
Offshore Wind ◽  
Sliding Mesh ◽  
Unsteady Aerodynamic ◽  
Floating Wind Turbine ◽  
Mesh Method ◽  
Offshore Floating Wind Turbine ◽  
Platform Motions

Abstract Offshore wind energy developed rapidly in recent years. Due to the platform motions causing by ocean waves, the aerodynamics of floating offshore wind turbines (FOWT) show strong unsteady characters than onshore wind turbines. The widely used methods to investigate the unsteady aerodynamic performance of wind turbine are Blade Element Momentum (BEM) and Free-Vortex Wake (FVW) methods. The accuracy of these two methods strongly depend on empirical formula or correction models. However, for dynamics motions of wind turbine, there is still a lack of accurate models. CFD simulations using overset or dynamic mesh methods also have been used for FOWT aerodynamic investigations. However, the mesh deforming or reconstruction methods are usually suitable for small movement of wind turbine blade. In this paper, a dual-sliding mesh method is employed to simulate the unsteady aerodynamic characters of an offshore floating wind turbine with supporting platform motions using Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations. Both rotor rotation and platform motions are treated as rigid angular motions. The relative motion and data exchange were simulated using sliding mesh method. The NREL 5MW reference wind turbine with platform pitching and rolling motions are considered. The pitching and rolling motions of floating platform are simplified in the form of a prescribed sinusoidal function. Different conditions with two amplitudes and two frequencies of pitching and rolling motions were investigated. URANS were performed with full structured mesh for wind turbine rotor using commercial software FLUENT. The platform motions were set using User Defined Function (UDF). Transitional Shear Stress Turbulence (T-SST) model was employed. The simulation results were compared with BEM method and FVW method results. Both steady status and dynamic pitching processes are investigated. The variations of wind turbine aerodynamic load, as well as the aerodynamic character of airfoils at different spanwise positions, were obtained and analyzed in detail. The simulations results show that the platform pitching introduce remarkable influence on the wind turbine aerodynamic performance. The platform pitching has much larger influence on the wind turbine power and thrust than the platform rolling. The dual-sliding mesh method shows potentials to investigation the dynamic process with multiple rigid motions.

Numerical Simulation on the Flow Control by Mounting Indented Gurney Flaps for a Wind Turbine

2012 ◽  
Vol 512-515 ◽  
pp. 623-627 ◽  
Author(s):  
Wan Li Zhao ◽  
Xiao Lei Zheng
Keyword(s):  
Numerical Simulation ◽  
Wind Turbine ◽  
Numerical Investigation ◽  
Wind Turbines ◽  
Aerodynamic Performance ◽  
Optimal Position ◽  
Gurney Flaps ◽  
Turbine Performance ◽  
Gurney Flap ◽  
Practical Engineering

Numerical investigation of large thick and low Reynolds airfoil of wind turbines by mounting indented Gurney flaps was carried out. The influenced rules of the position of Gurney flaps on the aerodynamic performance of airfoil under same height of flaps were achieved, and the optimal position of Gurney flap was presented. At last, the mechanism of wind turbine performance controlled by Gurney flap was discussed. The results can provide the theoretical guidance and technical support to wind turbines control in practical engineering.

scholarly journals Impact of Economic Indicators on the Integrated Design of Wind Turbine Systems

2018 ◽  
Vol 8 (9) ◽  
pp. 1668 ◽  
Author(s):  
Jianghai Wu ◽  
Tongguang Wang ◽  
Long Wang ◽  
Ning Zhao
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Energy Production ◽  
Large Scale ◽  
Wind Farm ◽  
Net Present Value ◽  
Integrated Design ◽  
Aerodynamic Performance ◽  
System Level ◽  
Blade Length

This article presents a framework to integrate and optimize the design of large-scale wind turbines. Annual energy production, load analysis, the structural design of components and the wind farm operation model are coupled to perform a system-level nonlinear optimization. As well as the commonly used design objective levelized cost of energy (LCoE), key metrics of engineering economics such as net present value (NPV), internal rate of return (IRR) and the discounted payback time (DPT) are calculated and used as design objectives, respectively. The results show that IRR and DPT have the same effect as LCoE since they all lead to minimization of the ratio of the capital expenditure to the energy production. Meanwhile, the optimization for NPV tends to maximize the margin between incomes and costs. These two types of economic metrics provide the minimal blade length and maximal blade length of an optimal blade for a target wind turbine at a given wind farm. The turbine properties with respect to the blade length and tower height are also examined. The blade obtained with economic optimization objectives has a much larger relative thickness and smaller chord distributions than that obtained for high aerodynamic performance design. Furthermore, the use of cost control objectives in optimization is crucial in improving the economic efficiency of wind turbines and sacrificing some aerodynamic performance can bring significant reductions in design loads and turbine costs.

Planetary Gear for Counter-Rotating Wind Turbines

2014 ◽  
Vol 658 ◽  
pp. 135-140 ◽  
Author(s):  
Radu Saulescu ◽  
Codruta Jaliu ◽  
Olimpiu Munteanu ◽  
Oliver Climescu
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Rotation Speed ◽  
Planetary Gear ◽  
Electrical Energy ◽  
Turbine Rotor ◽  
Higher Power ◽  
Electrical Generator ◽  
High Rotation Speed ◽  
The Difference

A specific problem of the wind turbines refers to the difference between the low rotation speed of the wind turbine rotor and the high rotation speed needed for the electrical generator. Usually, the adaptation between the speed of the turbine rotor and the electrical generator speed is achieved by means of a speed increaser. A recent alternative relates to the use of coaxial counter-rotating wind turbines, which can achieve higher power and improve the conversion efficiency of the wind energy into electrical energy (up to 25%) with a reduced cost of approx. 20-30% compared to similar single rotor turbines. Conceptually, the counter-rotating wind turbine systems can integrate a particular generator wherein the rotor is coupled to a row of blades and the stator with another row of blades, or a commonly generator, coupled to a differential planetary gear, that allows the summation of the blades motions.The paper describes and analyzes kinematic and dynamic aspects of a system consisting of two coaxial counter-rotating turbines and a generator, interconnected by a planetary gear with two inputs (the two turbines) and an output (the generator). The algorithm is based on the property of the differential planetary gear of adding two input motions into one output motion. The kinematic and dynamic parameters of the planetary gear are established in the paper, and a case study is further presented: a small wind turbine equipped with a transmission enabling input speed multiplication.

An Evaluation of Drag Coefficient of Wind Turbine System Installed on Moving Car

2014 ◽  
Vol 660 ◽  
pp. 689-693 ◽  
Author(s):  
Mohd Sofian ◽  
Rosly Nurhayati ◽  
A.Jamit Rexca ◽  
S. Shamsudin Syariful ◽  
Abdullah Aslam
Keyword(s):  
Drag Coefficient ◽  
Wind Turbine ◽  
Air Flow ◽  
Aerodynamic Performance ◽  
Ansys Fluent ◽  
Car Body ◽  
Wind Turbine System ◽  
Fluent Software ◽  
Suitable Area

This study presents a simulation result of an evaluation of the aerodynamic performance of a moving car with a wind turbine system. Sedan type cars (approaching the size of Proton Wira car) were modeled using the SolidWork software and simulation was done by ANSYS FLUENT software. Three car models with different wind turbine system positions (in front of the front bumper, on top of the hood and on top of the roof) plus one model without the wind turbine system were simulated. The study proved that the position of the wind turbine system installation will change the characteristic of the air flow around the car body and affects the aerodynamic performance of the car. Extended front bumper of a car is not significantly affecting the aerodynamic performance of the car. This extended bumper seems to be the suitable area to install a wind turbine system and the investigation shows that the aerodynamic performance of the car improved due to lower drag coefficient, Cd..

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