Bladelets—Winglets on Blades of Wind Turbines: A Multiobjective Design Optimization Study

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Sohail R. Reddy ◽  
George S. Dulikravich ◽  
Helmut Sobieczky ◽  
Manuel Gonzalez
Keyword(s):  
Wind Turbine ◽  
Design Optimization ◽  
Stokes Equations ◽  
Thrust Force ◽  
Flow Analysis ◽  
Turbine Rotor ◽  
Response Surfaces ◽  
Field Analysis ◽  
High Fidelity ◽  
Horizontal Axis Wind Turbine

The work presented in this paper used rigorous 3D flow-field analysis combined with multi-objective constrained shape design optimization for the design of complete blade + bladelet configurations for a three-blade horizontal-axis wind turbine. The fluid flow analysis in this work was performed using Openfoam software. The 3D, steady, incompressible, turbulent flow Reynolds-Averaged Navier–Stokes equations were solved in the rotating frame of reference for each combination of wind turbine blade and bladelet geometry. The free stream uniform wind speed in all cases was assumed to be 9 m s−1. The three simultaneous design optimization objectives were as follows: (a) maximize the coefficient of power, (b) minimize the coefficient of thrust force, and (c) minimize twisting moment around the blade axis. The bladelet geometry was fully defined by using a small number of parameters. The optimization was carried out by creating a multidimensional response surface for each of the simultaneous objectives. The response surfaces were based on radial basis functions, where the support points were designs analyzed using the high-fidelity computational fluid dynamics (CFD) analysis of the full blade + bladelet geometry. The response surfaces were then coupled to an optimization algorithm in modefrontier software. The predicted values of the objective functions for the optimum designs were then again validated using Openfoam high-fidelity analysis code. Results for a Pareto-optimized bladelet on a given blade indicate that more than 4% increase in the coefficient of power at minimal thrust force penalty is possible at off-design conditions compared to the same wind turbine rotor blade without a bladelet.

Bladelets-Winglets on Blades of Wind Turbines: A Multiobjective Design Optimization Study

2017 ◽  
Author(s):  
Sohail R. Reddy ◽  
George S. Dulikravich ◽  
Helmut Sobieczky
Keyword(s):  
Wind Turbine ◽  
Design Optimization ◽  
Stokes Equations ◽  
Flow Analysis ◽  
Turbine Rotor ◽  
Response Surfaces ◽  
Field Analysis ◽  
High Fidelity ◽  
Multi Objective ◽  
Computational Fluid Dynamics Analysis

The work presented in this paper used rigorous 3D flow-field analysis combined with multi-objective constrained shape design optimization for the design of bladelet (winglet) configurations for a three-blade propeller type wind turbine. The fluid flow analysis in this work was performed using 3D, steady, incompressible, turbulent flow Reynolds-averaged Navier-Stokes equations in the rotating frame of reference for each combination of a given wind turbine blade and a varying bladelet geometry. The free stream uniform wind speed in all cases was assumed to be 9 m s−1 and rotational speed was 12 rpm. These were off-design conditions for this rotor. The three simultaneous design optimization objectives were: a) maximize the coefficient of power, b) minimize the coefficient of thrust, and c) minimize twisting moment around the blade axis. The bladelet geometry was fully defined by using a small number of parameters. The optimization was carried out by creating a multi-dimensional response surface for each of the simultaneous objectives. The response surfaces were based on radial basis functions, where the support points were designs analyzed using the high fidelity CFD analysis of the full blade + bladelet geometry. The response surfaces were then coupled to a multi-objective optimization algorithm. The predicted values of the objective functions for the optimum designs were then again validated using the high fidelity computational fluid dynamics analysis code. Results for a Pareto optimized bladelet on a given blade indicate that more than 4% increase in the coefficient of power at minimal thrust force penalty is possible compared to the same wind turbine rotor blade without a bladelet.

scholarly journals Estimation of wind turbine blade aerodynamic performances computed using different numerical approaches

2018 ◽  
Vol 45 (1) ◽  
pp. 53-65 ◽  
Author(s):  
Jelena Svorcan ◽  
Ognjen Pekovic ◽  
Toni Ivanov
Keyword(s):  
Wind Turbine ◽  
Thrust Force ◽  
Turbulence Models ◽  
Turbine Rotor ◽  
Momentum Balance ◽  
Horizontal Axis Wind Turbine ◽  
Ansys Fluent ◽  
Force Coefficients ◽  
Aerodynamic Performances ◽  
Numerical Approaches

Although much employed, wind energy systems still present an open, contemporary topic of many research studies. Special attention is given to precise aerodynamic modeling performed in the beginning since overall wind turbine performances directly depend on blade aerodynamic performances. Several models different in complexity and computational requirements are still widely used. Most common numerical approaches include: i) momentum balance models, ii) potential flow methods and iii) full computational fluid dynamics solutions. Short explanations, reviews and comparison of the existing computational concepts are presented in the paper. Simpler models are described and implemented while numerous numerical investigations of isolated horizontal-axis wind turbine rotor consisting of three blades have also been performed in ANSYS FLUENT 16.2. Flow field is modeled by Reynolds Averaged Navier-Stokes (RANS) equations closed by two different turbulence models. Results including global parameters such as thrust and power coefficients as well as local distributions along the blade obtained by different models are compared to available experimental data. Presented results include fluid flow visualizations in the form of velocity contours, sectional pressure distributions and values of power and thrust force coefficients for a range of operational regimes. Although obtained numerical results vary in accuracy, all presented numerical settings seem to slightly under- or over-estimate the global wind turbine parameters (power and thrust force coefficients). Turbulence can greatly affect the wind turbine aerodynamics and should be modeled with care.

Numerical Studies of the Effects of Active and Passive Circulation Enhancement Concepts on Wind Turbine Performance

2006 ◽  
Vol 128 (4) ◽  
pp. 432-444 ◽  
Author(s):  
Chanin Tongchitpakdee ◽  
Sarun Benjanirat ◽  
Lakshmi N. Sankar
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Horizontal Axis Wind Turbine ◽  
Trailing Edge ◽  
Low Wind Speed ◽  
Gurney Flap ◽  
Coanda Jet

The aerodynamic performance of a wind turbine rotor equipped with circulation enhancement technology (trailing-edge blowing or Gurney flaps) is investigated using a three-dimensional unsteady viscous flow analysis. The National Renewable Energy Laboratory Phase VI horizontal axis wind turbine is chosen as the baseline configuration. Experimental data for the baseline case is used to validate the flow solver, prior to its use in exploring these concepts. Calculations have been performed for axial and yawed flow at several wind conditions. Results presented include radial distribution of the normal and tangential forces, shaft torque, root flap moment, and surface pressure distributions at selected radial locations. At low wind speed (7m∕s) where the flow is fully attached, it is shown that a Coanda jet at the trailing edge of the rotor blade is effective at increasing circulation resulting in an increase of lift and the chordwise thrust force. This leads to an increased amount of net power generation compared to the baseline configuration for moderate blowing coefficients (Cμ⩽0.075). A passive Gurney flap was found to increase the bound circulation and produce increased power in a manner similar to Coanda jet. At high wind speed (15m∕s) where the flow is separated, both the Coanda jet and Gurney flap become ineffective. The effects of these two concepts on the root bending moments have also been studied.

Turbulent Unsteady Flow Analysis of Horizontal Axis Wind Turbine Airfoil Aerodynamics Based on the Harmonic Balance Reynolds-Averaged Navier-Stokes Equations

2014 ◽  
Author(s):  
M. Sergio Campobasso ◽  
Fabio Gigante ◽  
Jernej Drofelnik
Keyword(s):  
Wind Turbine ◽  
Time Domain ◽  
Harmonic Balance ◽  
Stokes Equations ◽  
Transport Model ◽  
Flow Analysis ◽  
Horizontal Axis ◽  
Navier Stokes ◽  
Horizontal Axis Wind Turbine ◽  
Reynolds Averaged Navier Stokes

Several horizontal axis wind turbine unsteady flows, such as that associated with the yawed wind regime, are predominantly periodic. Harmonic balance Reynolds-averaged Navier-Stokes solvers can be used to accurately analyze such flows substantially faster than what their time-domain counterparts can do. The paper presents the mathematical and numerical features of a new turbulent harmonic balance Navier-Stokes solver using Menter’s shear stress transport model for the turbulence closure. The effectiveness of the developed technology is demonstrated by using two-dimensional harmonic balance flow simulations to determine the periodic aerodynamic loads acting on a blade section of a 164 m-diameter wind turbine rotor in yawed wind. Presented results highlight that the turbulent harmonic balance solver can compute the sectional hysteresis force cycles more than 10 times faster than its time-domain counterpart, and with an accuracy comparable to that of the time-domain solver.

Numerical Simulations of the Aerodynamics of Circulation Control Wind Turbines Under Yawed Flow Conditions

2010 ◽  
Author(s):  
Lakshmi N. Sankar ◽  
Chanin Tongchitpakdee ◽  
Mina Zaki ◽  
Robert Englar
Keyword(s):  
Wind Turbine ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Circulation Control ◽  
Horizontal Axis Wind Turbine ◽  
Flow Solver ◽  
Wind Speeds ◽  
Low Wind Speeds ◽  
Nrel Phase Vi

The aerodynamic performance of a wind turbine rotor equipped with circulation control technology is investigated using a three-dimensional unsteady viscous flow analysis. The National Renewable Energy Laboratory (NREL) Phase VI horizontal axis wind turbine (HAWT) is chosen as the baseline configuration. Experimental data for the baseline case is used to validate the flow solver, prior to its use in exploring these concepts. Steady and pulsed Coanda jet calculations have been performed for axial and yawed flows at several wind conditions. Results presented include radial distribution of the normal and tangential forces at selected radial locations, shaft torque, and root flap bending moments. At low wind speeds where the flow is fully attached, it is found that steady and pulsed Coanda jets at the trailing edge are both effective at increasing circulation resulting in an increase of lift and the chordwise thrust force. This leads to an increased amount of net power compared to the baseline configuration for moderate blowing coefficients. Preliminary calculations are also shown to demonstrate how Coanda jets may be used as jet spoilers to alleviate structural loads under extreme wind conditions.

scholarly journals Insight into Rotational Effects on a Horizontal Axis Wind Turbine NREL Phase ii Using CFD simulation and inverse BEM

2017 ◽  
Vol 2 (1) ◽  
pp. 29
Author(s):  
Belamadi Riyadh
Keyword(s):  
Wind Turbine ◽  
Phase Ii ◽  
Cfd Simulation ◽  
Stokes Equations ◽  
Large Deviation ◽  
Aerodynamic Characteristics ◽  
Turbine Rotor ◽  
Horizontal Axis ◽  
Horizontal Axis Wind Turbine ◽  
Wind Turbine Rotor

The present work aims to study the aerodynamic characteristics of the NREL phase II rotor (generated only with S809 profile along the span for an untwisted case) that is a horizontal axis downwind wind turbine rotor and which is assumed to stand isolated in the space. The three-dimensional steady-incompressible flow Reynolds Averaged Navier-Stokes equations are solved by using the commercial CFD package ANSYS FLUENT and, the turbulence closure model k-ω with shear stress transport correction was adopted for all computations. The computations were done for wind speed of 7.2, 10.56, 12.85, 16.3, and 9.18 m.s-1. Results of pressure and torque for considered wind turbine rotor have been directly compared to the available experimental data. The comparisons show that CFD results along with the turbulence model can predict the span-wise loading of the wind turbine rotor with reasonable agreement. Secondly, A comparison of lift and drag coefficients was made between the results obtained using the inverse algorithm BEM based on the calculated pressure distributions and the experimental test data. The result show that the general trend is similar for all sections of the scale, however, large deviation exists between the 2-D and   3-D case.

scholarly journals Aeromechanical Analysis of a Complete Wind Turbine Using Nonlinear Frequency Domain Solution Method

2020 ◽  
Author(s):  
Shine Win Naung ◽  
Mohammad Rahmati ◽  
Hamed Farokhi
Keyword(s):  
Wind Turbine ◽  
Frequency Domain ◽  
Solution Method ◽  
Computational Cost ◽  
Turbine Rotor ◽  
Forced Response ◽  
High Fidelity ◽  
Nonlinear Frequency ◽  
Cfd Method ◽  
Turbine Model

Abstract The high-fidelity computational fluid dynamics (CFD) simulations of a complete wind turbine model usually require significant computational resources. It will require much more resources if the fluid-structure interactions between the blade and the flow are considered, and it has been the major challenge in the industry. The aeromechanical analysis of a complete wind turbine model using a high-fidelity CFD method is discussed in this paper. The distinctiveness of this paper is the application of the nonlinear frequency domain solution method to analyse the forced response and flutter instability of the blade as well as to investigate the unsteady flow field across the wind turbine rotor and the tower. This method also enables the aeromechanical simulations of wind turbines for various inter blade phase angles in a combination with a phase shift solution method. Extensive validations of the nonlinear frequency domain solution method against the conventional time domain solution method reveal that the proposed frequency domain solution method can reduce the computational cost by one to two orders of magnitude.

Analysis of Unsteady Flows Past Horizontal Axis Wind Turbine Airfoils Based on Harmonic Balance Compressible Navier-Stokes Equations With Low-Speed Preconditioning

2011 ◽  
Author(s):  
M. Sergio Campobasso ◽  
Mohammad H. Baba-Ahmadi
Keyword(s):  
Wind Turbine ◽  
Time Domain ◽  
Harmonic Balance ◽  
Stokes Equations ◽  
Unsteady Aerodynamics ◽  
Horizontal Axis ◽  
Navier Stokes ◽  
Horizontal Axis Wind Turbine ◽  
Low Speed ◽  
Computational Performance

This paper presents the numerical models underlying the implementation of a novel harmonic balance compressible Navier-Stokes solver with low-speed preconditioning for wind turbine unsteady aerodynamics. The numerical integration of the harmonic balance equations is based on a multigrid iteration, and, for the first time, a numerical instability associated with the use of such an explicit approach in this context is discussed and resolved. The harmonic balance solver with low-speed preconditioning is well suited for the analyses of several unsteady periodic low-speed flows, such as those encountered in horizontal axis wind turbines. The computational performance and the accuracy of the technology being developed are assessed by computing the flow field past two sections of a wind turbine blade in yawed wind with both the time- and frequency-domain solvers. Results highlight that the harmonic balance solver can compute these periodic flows more than 10 times faster than its time-domain counterpart, and with an accuracy comparable to that of the time-domain solver.

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