New Insight Into the Flow Around a Wind Turbine Airfoil Section1

2005 ◽  
Vol 127 (2) ◽  
pp. 214-222 ◽  
Author(s):  
F. Bertagnolio ◽  
N. N. Sørensen ◽  
F. Rasmussen
Keyword(s):  
Wind Turbine ◽  
Numerical Models ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Pitching Airfoil ◽  
Wind Turbine Airfoil

The objective of this paper is an improved understanding of the physics of the aeroelastic motion of wind turbine blades in order to improve the numerical models used for their design. Two- and three-dimensional Navier–Stokes calculations of the flow around a wind turbine airfoil using the k−ω SST and Detached Eddy Simulation (DES) turbulence models, as well as an engineering semiempirical dynamic stall model, are conducted. The computational results are compared to the experimental results that are available for both the static airfoil and the pitching airfoil. It is shown that the Navier–Stokes simulations can reproduce the main characteristic features of the flow. The DES model seems to be able to reproduce most of the details of the unsteady aerodynamics. Aerodynamic work computations indicate that a plunging motion of the airfoil can become unstable.

scholarly journals Comparative Study on CFD Turbulence Models for the Flow Field in Air Cooled Radiator

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1687
Author(s):  
Chao Yu ◽  
Xiangyao Xue ◽  
Kui Shi ◽  
Mingzhen Shao ◽  
Yang Liu
Keyword(s):  
Flow Field ◽  
Transient Flow ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Compartment Model ◽  
Navier Stokes ◽  
Engine Compartment ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Relevant Calculation

This paper compares the performances of three Computational Fluid Dynamics (CFD) turbulence models, Reynolds Average Navier-Stokes (RANS), Detached Eddy Simulation (DES), and Large Eddy Simulation (LES), for simulating the flow field of a wheel loader engine compartment. The distributions of pressure fields, velocity fields, and vortex structures in a hybrid-grided engine compartment model are analyzed. The result reveals that the LES and DES can capture the detachment and breakage of the trailing edge more abundantly and meticulously than RANS. Additionally, by comparing the relevant calculation time, the feasibility of the DES model is proved to simulate the three-dimensional unsteady flow of engine compartment efficiently and accurately. This paper aims to provide a guiding idea for simulating the transient flow field in the engine compartment, which could serve as a theoretical basis for optimizing and improving the layout of the components of the engine compartment.

Aeroacoustics response of wind turbine blade profiles in normal and icing conditions

2018 ◽  
Vol 42 (3) ◽  
pp. 243-251 ◽  
Author(s):  
Edison H Caicedo ◽  
Muhammad S Virk
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Numerical Study ◽  
Turbulence Models ◽  
Wind Turbine Blade ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Eddy Simulation

This article describes a multiphase computational fluid dynamics–based numerical study of the aeroacoustics response of symmetric and asymmetric wind turbine blade profiles in both normal and icing conditions. Three different turbulence models (Reynolds-averaged Navier–Stokes, detached eddy simulation, and large eddy simulation) have been used to make a comparison of numerical results with the experimental data, where a good agreement is found between numerical and experimental results. Detached eddy simulation turbulence model is found suitable for this study. Later, an extended computational fluid dynamics–based aeroacoustics parametric study is carried out for both normal (clean) and iced airfoils, where the results indicate a significant change in sound levels for iced profiles as compared to clean.

Detached-Eddy Simulation of Flow Around the NREL Phase-VI Blade

2002 ◽  
Author(s):  
J. Johansen ◽  
N. N. So̸rensen ◽  
J. A. Michelsen ◽  
S. Schreck
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Simulation Model ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Reynolds Averaged Navier Stokes ◽  
Nrel Phase Vi

The Detached-Eddy Simulation model implemented in the computational fluid dynamics code, EllipSys3D, is applied on the flow around the NREL Phase-VI wind turbine blade. Results are presented for flow around a parked blade at fixed angle of attack and a blade pitching along the blade axis. Computed blade characteristics are compared with experimental data from the NREL/NASA Ames Phase-VI unsteady experiment. The Detached-Eddy Simulation model is a method for predicting turbulence in computational fluid dynamics computations, which combines a Reynolds Averaged Navier-Stokes method in the boundary layer with a Large Eddy Simulation in the free shear flow. The present study focuses on static and dynamic stall regions highly relevant for stall regulated wind turbines. Computations do predict force coefficients and pressure distributions fairly good and results using Detached-Eddy Simulation show considerably more three-dimensional flow structures compared to conventional two-equation Reynolds Averaged Navier-Stokes turbulence models, but no particular improvements are seen on the global blade characteristics.

scholarly journals Techniques for Turbulence Tripping of Boundary Layers in RANS Simulations

2021 ◽  
Author(s):  
Narges Tabatabaei ◽  
Ricardo Vinuesa ◽  
Ramis Örlü ◽  
Philipp Schlatter
Keyword(s):  
Boundary Layer ◽  
Passive Control ◽  
Target Location ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Transition Process ◽  
Navier Stokes ◽  
Test Cases ◽  
And Performance

AbstractThe exact placement of the laminar–turbulent transition has a significant effect on relevant characteristics of the boundary layer and aerodynamics, such as drag, heat transfer and flow separation on e.g. wings and turbine blades. Tripping, which fixes the transition position, has been a valuable aid to wind-tunnel testing during the past 70 years, because it makes the transition independent of the local condition of the free-stream. Tripping helps to obey flow similarity for scaled models and serves as a passive control mechanism. Fundamental fluid-mechanics studies and many engineering developments are based on tripped cases. Therefore, it is essential for computational fluid dynamics (CFD) simulations to replicate the same forced transition, in spite of the advanced improvements in transition modelling. In the last decade, both direct numerical simulation (DNS) and large-eddy simulations (LES) include tripping methods in an effort to avoid the need for modeling the complex mechanisms associated with the natural transition process, which we would like to bring over to Reynolds-averaged Navier–Stokes (RANS) turbulence models. This paper investigates the implementation and performance of such a technique in RANS and specifically in the $$k-\omega$$ k - ω SST model. This study assesses RANS tripping with three alternatives: First, a recent approach of turbulence generation, denoted as turbulence-injection method (kI), is evaluated and investigated through different test cases; second, a predefined transition point is used in a traditional transition model (denoted as IM method); and third a novel formulation combining the two previous methods is proposed, denoted $$\gamma -k$$ γ - k I. The model is compared with DNS, LES and experimental data in a variety of test cases ranging from a turbulent boundary layer on a flat plate to the three-dimensional (3D) flow over a wing section. The desired tripping is achieved at the target location and the simulation results compare very well with the reference results. With the application of the novel model, the challenging transition region can be excluded from a simulation, and consequently more reliable results can be provided.

Characterization of Three-Dimensional Effects for the Rotating and Parked NREL Phase VI Wind Turbine

2006 ◽  
Vol 128 (4) ◽  
pp. 445-454 ◽  
Author(s):  
Sven Schmitz ◽  
Jean-Jacques Chattot
Keyword(s):  
Wind Turbine ◽  
Computational Models ◽  
Three Dimensional ◽  
Vortex Sheet ◽  
Inviscid Flow ◽  
Radial Force ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Flow Conditions ◽  
Dimensional Effects

This paper addresses three-dimensional effects which are pertinent to wind turbine aerodynamics. Two computational models were applied to the National Renewable Energy Laboratory Phase VI Rotor under rotating and parked conditions, a vortex line method using a prescribed wake, and a parallelized coupled Navier-Stokes/vortex-panel solver (PCS). The linking of the spanwise distribution of bound circulation between both models enabled the quantification of three-dimensional effects with PCS. For the rotating turbine under fully attached flow conditions, the effects of the vortex sheet dissipation and replacement by a rolled-up vortex on the computed radial force coefficients were investigated. A quantitative analysis of both radial pumping and Coriolis effect, known as the Himmelskamp effect, was performed for viscous as well as inviscid flow. For the parked turbine, both models were applied at various pitch angles corresponding to fully attached as well as stalled flow. For partially stalled flow, computed results revealed a vortical structure trailing from the blade’s upper surface close to the 40% radial station. This trailing vortex was documented as a highly unsteady flow structure in an earlier detached eddy simulation by another group, however, it was not directly observed experimentally but only inferred. Computed results show very good agreement with measured wind tunnel data for the PCS model. Finally, a new method for extracting three-dimensional airfoil data is proposed that is particularly well suited for highly stalled flow conditions.

Viscous Flow Computations on a Smooth Cylinders: A Detailed Numerical Study With Validation

2007 ◽  
Author(s):  
Guilherme Vaz ◽  
Christophe Mabilat ◽  
Remmelt van der Wal ◽  
Paul Gallagher
Keyword(s):  
Experimental Data ◽  
Viscous Flow ◽  
Numerical Study ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Time Step ◽  
Drag Forces

The objective of this paper is to investigate several numerical and modelling features that the CFD community is currently using to compute the flow around a fixed smooth circular cylinder. Two high Reynolds numbers, 9 × 104 and 5 × 105, are chosen which are in the so called drag-crisis region. Using a viscous flow solver, these features are assessed in terms of quality by comparing the numerical results with experimental data. The study involves grid sensitivity, time step sensitivity, the use of different turbulence models, three-dimensional effects, and a RANS/DES (Reynolds Averaged Navier Stokes, Detached Eddy Simulation) comparison. The resulting drag forces and Strouhal numbers are compared with experimental data of different sources. Major flow features such as velocity and vorticity fields are presented. One of the main conclusions of the present study is that all models predict forces which are far from the experimental values, particularly for the higher Reynolds numbers in the drag-crisis region. Three-dimensional and unsteadiness effects are present, but are only fully captured by sophisticated turbulence models or by DES. DES seems to be the key to better solve the flow problem and obtain better agreement with experimental data. However, its considerable computational demands still do not allow to use it for engineering design purposes.

Investigating Three-Dimensional and Rotational Effects on Wind Turbine Blades by Means of a Quasi-3D Navier-Stokes Solver

2000 ◽  
Vol 122 (2) ◽  
pp. 330-336 ◽  
Author(s):  
P. K. Chaviaropoulos ◽  
M. O. L. Hansen
Keyword(s):  
Wind Turbine ◽  
Stokes Equations ◽  
Twist Angle ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Viscous Effects ◽  
Wind Turbine Blades ◽  
Mean Values ◽  
Power Curves

Three-dimensional and rotational viscous effects on wind turbine blades are investigated by means of a quasi-3D Navier-Stokes model. The governing equations of the model are derived from the 3-D primitive variable Navier-Stokes equations written in cylindrical coordinates in the rotating frame of reference. The latter are integrated along the radial direction and certain assumptions are made for the mean values of the radial derivatives. The validity of these assumptions is cross-checked through fully 3-D Navier-Stokes calculations. The resulting quasi-3D model suggests that three-dimensional and rotational effects be strongly related to the local chord by radii ratio and the twist angle. The equations of the model are numerically integrated by means of a pressure correction algorithm. Both laminar and turbulent flow simulations are performed. The former is used for identifying the physical mechanism associated with the 3-D and rotational effects, while the latter for establishing semiempirical correction laws for the load coefficients, based on 2-D airfoil data. Comparing calculated and measured power curves of a stall controlled wind turbine, it is shown that the suggested correction laws may improve significantly the accuracy of the predictions. [S0098-2202(00)02702-4]

scholarly journals Darrieus wind turbine blade unsteady aerodynamics: a three-dimensional Navier-Stokes CFD assessment

Energy ◽  
2017 ◽  
Vol 128 ◽  
pp. 550-563 ◽  
Author(s):  
Francesco Balduzzi ◽  
Jernej Drofelnik ◽  
Alessandro Bianchini ◽  
Giovanni Ferrara ◽  
Lorenzo Ferrari ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Wind Turbine Blade ◽  
Navier Stokes

Performance enhancement of Savonius wind turbine by blade shape and twisted angle modifications

2021 ◽  
pp. 095765092098794
Author(s):  
Ahmed M Nagib Elmekawy ◽  
Hassan A Hassan Saeed ◽  
Sadek Z Kassab
Keyword(s):  
Wind Turbine ◽  
Performance Enhancement ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Vertical Axis ◽  
Cfd Simulations ◽  
Sliding Mesh ◽  
Blade Shape ◽  
Rotor Shape ◽  
Twisting Angle

Three-dimensional CFD simulations are carried out to study the increase of power generated from Savonius vertical axis wind turbines by modifying the blade shape and blade angel of twist. Twisting angle of the classical blade are varied and several proposed novel blade shapes are introduced to enhance the performance of the wind turbine. CFD simulations have been performed using sliding mesh technique of ANSYS software. Four turbulence models; realizable k -[Formula: see text], standard k - [Formula: see text], SST transition and SST k -[Formula: see text] are utilized in the simulations. The blade twisting angle has been modified for the proposed dimensions and wind speed. The introduced novel blade increased the power generated compared to the classical shapes. The two proposed novel blades achieved better power coefficients. One of the proposed models achieved an increase of 31% and the other one achieved 32.2% when compared to the classical rotor shape. The optimum twist angel for the two proposed models achieved 5.66% and 5.69% when compared with zero angle of twist.

scholarly journals Experimental and Numerical Investigation of 3D Dam-Break Wave Propagation in an Enclosed Domain with Dry and Wet Bottom

2021 ◽  
Vol 11 (12) ◽  
pp. 5638
Author(s):  
Selahattin Kocaman ◽  
Stefania Evangelista ◽  
Hasan Guzel ◽  
Kaan Dal ◽  
Ada Yilmaz ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Numerical Models ◽  
Three Dimensional ◽  
Dam Break ◽  
Dam Failure ◽  
Navier Stokes ◽  
Negative Wave ◽  
Through Flow ◽  
Instantaneous Removal ◽  
Surface Patterns

Dam-break flood waves represent a severe threat to people and properties located in downstream regions. Although dam failure has been among the main subjects investigated in academia, little effort has been made toward investigating wave propagation under the influence of tailwater depth. This work presents three-dimensional (3D) numerical simulations of laboratory experiments of dam-breaks with tailwater performed at the Laboratory of Hydraulics of Iskenderun Technical University, Turkey. The dam-break wave was generated by the instantaneous removal of a sluice gate positioned at the center of a transversal wall forming the reservoir. Specifically, in order to understand the influence of tailwater level on wave propagation, three tests were conducted under the conditions of dry and wet downstream bottom with two different tailwater depths, respectively. The present research analyzes the propagation of the positive and negative wave originated by the dam-break, as well as the wave reflection against the channel’s downstream closed boundary. Digital image processing was used to track water surface patterns, and ultrasonic sensors were positioned at five different locations along the channel in order to obtain water stage hydrographs. Laboratory measurements were compared against the numerical results obtained through FLOW-3D commercial software, solving the 3D Reynolds-Averaged Navier–Stokes (RANS) with the k-ε turbulence model for closure, and Shallow Water Equations (SWEs). The comparison achieved a reasonable agreement with both numerical models, although the RANS showed in general, as expected, a better performance.

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