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

Author(s):  
Sohail R. Reddy ◽  
George S. Dulikravich ◽  
Helmut Sobieczky

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.

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Sohail R. Reddy ◽  
George S. Dulikravich ◽  
Helmut Sobieczky ◽  
Manuel Gonzalez

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.


2020 ◽  
Author(s):  
Shine Win Naung ◽  
Mohammad Rahmati ◽  
Hamed Farokhi

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.


2006 ◽  
Vol 128 (4) ◽  
pp. 432-444 ◽  
Author(s):  
Chanin Tongchitpakdee ◽  
Sarun Benjanirat ◽  
Lakshmi N. Sankar

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.


2019 ◽  
Author(s):  
Lavi R. Zuhal ◽  
Ghifari A. Faza ◽  
Pramudita S. Palar ◽  
Koji Shimoyama

Author(s):  
Reza Yaghmaie ◽  
Onur Bilgen

Abstract This paper presents a comparison of low- and high-fidelity structural analyses of a 10 MW offshore floating wind turbine rotor blade. For low-fidelity analysis, BeamDyn as a part of the OpenFAST toolset is used. For high-fidelity analysis, the Toolkit for the Analysis of Composite Structures (TACS) finite element method is used. First, several numerical examples with reference solutions from the literature are investigated to compare the accuracy and efficiency of the low- and high-fidelity structural models. Next, the DTU 10 MW reference wind turbine blade is analyzed using both the low- and high-fidelity methods. The bending response of the blade is analyzed. The results show that the high-fidelity model agrees with low-fidelity results and reference solutions. The high-fidelity model represents the deformations more accurately than the low-fidelity model and therefore is appropriate for structural analysis of complex wind turbine blade shapes.


2022 ◽  
Author(s):  
Denis-Gabriel Caprace ◽  
Adam Cardoza ◽  
Andrew Ning ◽  
Marco Mangano ◽  
Sicheng He ◽  
...  

1980 ◽  
Vol 102 (1) ◽  
pp. 193-201 ◽  
Author(s):  
I. Khalil ◽  
W. Tabakoff ◽  
A. Hamed

A method for analyzing the viscous flow through turbomachine rotors is presented. The field analysis is based on the solution of the full Navier-Stokes equations over the rotor blade-to-blade stream channels. An Alternating-Direction-Implicit method is employed to carry out the necessary numerical integration of the elliptic governing equations. The flow analysis may be applied to various types of turbomachine rotors. Preliminarily, only the case of laminar flows are considered in this paper. The flow characteristics within the rotors of a radial inflow turbine and a radial bladed compressor are investigated over a wide range of operating conditions. Excellent results are obtained when compared with existing experimental data. The method of this analysis is quite general and can deal with wide range of applications. Possible modification of the present study to deal with turbulent flow cases are also identified.


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