Laminar flow and turbulence modeling to trace wake pattern around building clusters for domestic scale wind turbine siting

2009 ◽  
Author(s):  
Govindarajan A Chittaranjan
Keyword(s):  
Laminar Flow ◽  
Wind Turbine ◽  
Turbulence Modeling

Numerical Simulation of the Aerodynamic Performance of a H-Type Wind Turbine during Self-Starting

2014 ◽  
Vol 529 ◽  
pp. 296-302 ◽  
Author(s):  
Wei Zuo ◽  
Shun Kang
Keyword(s):  
Flow Field ◽  
Wind Turbine ◽  
Pitch Angle ◽  
Turbulence Modeling ◽  
Vertical Axis ◽  
Aerodynamic Performance ◽  
Time Dependent ◽  
Two Dimensional ◽  
Vertical Axis Wind Turbine ◽  
Sst Turbulence Model

The aerodynamic performance and the bypass flow field of a vertical axis wind turbine under self-starting are investigated using CFD simulations in this paper. The influence of pitch angle variations on the performance of the wind turbine during self-starting is presented. A two-dimensional model of the wind turbine with three blades is employed. A commercial software FlowVision is employed in this paper, which uses dynamic Cartesian grid. The SST turbulence model is used for turbulence modeling, which assumes the flow full turbulent. Based on the comparison between the computed time-dependent variations of the rotation speed with the experimental data, the time-dependent variations of the torque are presented. The characteristics of self-starting of the wind turbine are analyzed with the pitch angle of 0o、-2oand 2o. The influence of pitch angle variations on two-dimensional unsteady viscous flow field through velocity contours is discussed in detail.

Numerical Investigation of Mini Wind Turbines Near Highways

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Caelan Lapointe ◽  
Harish Gopalan
Keyword(s):  
Wind Turbine ◽  
Computer Aided Design ◽  
High Speed ◽  
Turbulence Modeling ◽  
Field Measurements ◽  
Vertical Axis ◽  
Motion Field ◽  
Vertical Axis Wind Turbine ◽  
Highway Traffic ◽  
Vehicle Motion

High-speed vehicle motion on the highways produces localized winds whose energy can be harnessed. These local winds have less variability especially if the highway traffic is constant. The idea of extracting energy from highway winds has been conceptualized in many studies before. However, the feasibility of this idea has never been tested using analytical, computation, or experimental methods. In this study, we numerically compute the amount of power that can be extracted from local highway winds due to vehicular motion. A unsteady Reynolds-averaged Navier–Stokes (URANS) method is used for modeling the atmospheric boundary layer (ABL). Realistic computer-aided design (CAD) models of cars and trucks separated by spacing information obtained from the existing standards are used to model the vehicle motion. A vertical axis wind turbine (VAWT) is used for extracting energy from the wind. The entire framework of ABL, vehicles, and turbine is simulated using overset grids and multiple translating and rotating frames of reference. Many vehicle motion scenarios were compared to the case of an isolated wind turbine. The initial results show a significant increase in the power that can be extracted by these turbines. The average extracted power increases about 317% when compared to the case without any vehicular motion. Field measurements or wind tunnel studies are required to provide validation for the computations and to determine if more advanced turbulence modeling methodologies have to be employed for these studies.

Determination of Wake Propagation Downstream of the Wind Turbine Using Computational Fluid Dynamics

2012 ◽  
Author(s):  
Abolfazl Pourrajabian ◽  
Reza Ebrahimi ◽  
Masoud Mirzaei
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Farm ◽  
Turbulence Modeling ◽  
Governing Equations ◽  
Horizontal Axis Wind Turbine ◽  
Velocity Magnitude

A numerical scheme for determination of wake propagation in downstream of a wind turbine was developed by Computational Fluid Dynamics (CFD) and analytical correlation. A 3bladed horizontal axis wind turbine was selected and airflow around the wind turbine was analyzed. The flow was assumed steady state and a pressure based approach was adopted to solve the governing equations in an unstructured grid distribution using parallel processing. In conjunction with governing equations, the kω – SST model was used for turbulence modeling. The formation of the wake behind the wind turbine was estimated and an appropriate equation was derived for velocity magnitude at the downstream of the wind turbine. Moreover, the suitable distances between wind turbines in wind and crosswind directions were estimated. Results show a good agreement between the previous researches and the comparison indicates that the CFD could be considered as a proper tool for determination of wake properties, windward and crosswind distance between wind turbines in a wind farm.

Methods for Improving Lift Force of Wind Turbine Aerofoil Blades during Low Wind Speed Conditions – A Review

2015 ◽  
Vol 787 ◽  
pp. 134-137
Author(s):  
S.P.R. Febi Ponwin ◽  
S. Rajkumar
Keyword(s):  
Reynolds Number ◽  
Renewable Energy ◽  
Wind Speed ◽  
Laminar Flow ◽  
Wind Turbine ◽  
Lift Force ◽  
Renewable Energy Sources ◽  
Small Scale ◽  
Good Efficiency ◽  
Low Wind Speed

Wind energy is one of the promising renewable energy resources. The challenges in utilizing the renewable energy sources are making them reliable with good efficiency. Wind turbine plays a major role in industrial power supply during heavy wind conditions. However, in domestic applications, the small scale wind turbine has major issue of low starting torque due to low wind speed near the ground surface. These conditions make the air motion as laminar flow with the Reynolds number less than 5x105. Hence, in some adverse condition there is a laminar flow separation which increases the drag and consequently reduces the lift force. This paper gives a comprehensive review on the investigations that are being carried out on low Reynolds number regime aerofoil and laminar separation bubble to enhance the lift force especially at low wind speed conditions.

scholarly journals On the Accuracy of uRANS and LES-Based CFD Modeling Approaches for Rotor and Wake Aerodynamics of the (New) MEXICO Wind Turbine Rotor Phase-III

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5198
Author(s):  
Shantanu Purohit ◽  
Ijaz Fazil Syed Ahmed Kabir ◽  
E. Y. K. Ng
Keyword(s):  
New Mexico ◽  
Wind Turbine ◽  
Turbulence Modeling ◽  
Absolute Error ◽  
Turbine Rotor ◽  
Tangential Component ◽  
Phase Iii ◽  
Scale Model ◽  
Cfd Modeling ◽  
Modeling Approaches

This work presents a comparison study of the CFD modeling with two different turbulence modeling approaches viz. unsteady RANS and LES, on a full-scale model of the (New) MEXICO rotor wind turbine. The main emphasis of the paper is on the rotor and wake aerodynamics. Simulations are carried out for the three wind speeds considered in the MEXICO experiment (10, 15, and 24 ms−1). The results of uRANS and LES are compared against the (New) MEXICO experimental measurements of pressure distributions, axial, radial, and azimuth traverse of three velocity components. The near wake characteristics and vorticity are also analyzed. The pressure distribution results show that the LES can predict the onset of flow separation more accurately than uRANS when the turbine operates in the stall condition. The LES can compute the flow structures in wake significantly better than the uRANS for the stall condition of the blade. For the design condition, the mean absolute error in axial and radial velocity components along radial traverse is less than 10% for both the modeling approaches, whereas tangential component error is less than 2% from the LES approach. The results also reveal that wake recovers faster in the uRANS approach, requiring further research of the far wake region using both CFD modeling approaches.

scholarly journals Distinct Turbulent Regions in the Wake of a Wind Turbine and Their Inflow-Dependent Locations: The Creation of a Wake Map

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5392
Author(s):  
Ingrid Neunaber ◽  
Michael Hölling ◽  
Richard J. A. M. Stevens ◽  
Gerard Schepers ◽  
Joachim Peinke
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Isotropic Turbulence ◽  
Turbulence Modeling ◽  
Wind Farms ◽  
Reference Case ◽  
Mean Velocity ◽  
Turbulence Analysis ◽  
Turbine Wake ◽  
Wind Turbine Wake

Wind turbines are usually clustered in wind farms which causes the downstream turbines to operate in the turbulent wakes of upstream turbines. As turbulence is directly related to increased fatigue loads, knowledge of the turbulence in the wake and its evolution are important. Therefore, the main objective of this study is a comprehensive exploration of the turbulence evolution in the wind turbine’s wake to identify characteristic turbulence regions. For this, we present an experimental study of three model wind turbine wake scenarios that were scanned with hot-wire anemometry with a very high downstream resolution. The model wind turbine was exposed to three inflows: laminar inflow as a reference case, a central wind turbine wake, and half of the wake of an upstream turbine. A detailed turbulence analysis reveals four downstream turbulence regions by means of the mean velocity, variance, turbulence intensity, energy spectra, integral and Taylor length scales, and the Castaing parameter that indicates the intermittency, or gustiness, of turbulence. In addition, a wake core with features of homogeneous isotropic turbulence and a ring of high intermittency surrounding the wake can be identified. The results are important for turbulence modeling in wakes and optimization of wind farm wake control.

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