Analysis of wake states by a full‐field actuator disc model

Sørensen, Jens Nørkær; Shen, Wen Zhong; Munduate, Xabier

doi:10.1002/(sici)1099-1824(199812)1:2<73::aid-we12>3.0.co;2-l

Cited by 161 publications

(101 citation statements)

References 1 publication

(1 reference statement)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the present work, it is proposed to choose the regularization parameter equal to the chord of the blade; ideally, it should be equal to the local chord; however, this is not possible since the model and the computational tool consider it constant along the blade span. The influence of ∈ has been studied for an actuator disk [23] and for actuator line [4,8] with special attention to the flow and wake dynamics. In this study, this parameter was chosen equal to the blade chord on the 5 sections in which the experiment took place.…”

Section: Isolated Rotor Simulations With Almentioning

confidence: 97%

Full Downwind Turbine Simulations Using Actuator Line Method

Matiz-Chicacausa

López

2018

Modelling and Simulation in Engineering

View full text Add to dashboard Cite

In the present work the actuator line (AL) technique is proposed to model a complete wind turbine (rotor and tower) in downwind configuration. The case study used is the Unsteady Aerodynamics Experiment (UAE) Phase VI turbine to analyze its suitability in capturing the tower shadow effect. Computational Fluid Dynamics (CFD) simulations were carried out using the open-source code OpenFOAM and the class of horizontal wind turbine AL from the toolbox SOWFA developed by the National Renewable Energy Laboratory (NREL). The objective of the present work is to validate the use of AL model for tower simulations and to establish whether such simplification is valid to capture the effect that tower shadow exerts over the rotor aerodynamics and to verify the accuracy of the proposed model regarding prediction of loads in the rotor. Computations were done first on an isolated rotor modelled with the AL technique; second on a full downwind turbine with AL in both rotor and tower; and, finally, on a 3D rotor with AL tower. Numerical results show good agreement with the experimental data concluding that the AL model is capable of a fast and accurate load prediction under certain conditions.

show abstract

Section: Isolated Rotor Simulations With Almentioning

confidence: 97%

Full Downwind Turbine Simulations Using Actuator Line Method

Matiz-Chicacausa

López

2018

Modelling and Simulation in Engineering

View full text Add to dashboard Cite

show abstract

“…For flows about rotors vortex breakdown has the same effect on the flow state as the so-called vortex ring state, which appears at high loadings (see e.g. Sørensen et al, [7]). Most theories for developing criteria for the onset of vortex breakdown are based on stability analysis of velocity distributions of the form of eqs.…”

Section: Rotor Induced Vortex Breakdownmentioning

confidence: 99%

Rotor aerodynamic power limits at low tip speed ratio using CFD

Mikkelsen

Sarmast

Henningson

et al. 2014

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

Abstract. When investigating limits of rotor aerodynamic models, the Betz limit serves as a solid marker of an upper limit which no model should be able to exceed. A century ago Joukowsky (1912) proposed a rotor aerodynamic model utilizing a rotating actuator disc with a constant circulation. This model has since then been the subject of much controversy as it predicts a power performance that for all tip speed ratios exceeds the Betz limit and which goes to infinity when the tip speed ratio goes to zero. Recently, it was demonstrated that the Joukowsky model is fully consistent with the inviscid Euler equations and that the apparent inconsistency partly can be explained by the lack of viscous effects (Sørensen and van Kuik [4]). However, even including a term to account for the effect of viscosity at small tip speed ratios, the model still predicts a power yield that exceeds the Betz limit. In the present work we study in detail, using a CFD actuator line model, the flow behavior for rotors at small tip speed ratios. It is shown that the excessive swirl appearing towards the rotor center at small tip speed ratios generates vortex breakdown, causing a recirculating zone in the wake that limits the power yield of the rotor. The appearance of vortex breakdown has a similar effect on the flow behavior as the vortex ring state that usually appears at higher tip speed ratios. Limits to where vortex breakdown might occur with tip speed ratio and rotor loading as parameter are investigated and presented in the paper. The limits found correspond to well-known criterion for vortex breakdown onset for swirling flows in general. By applying a criterion for vortex breakdown in combination with the general momentum theory, the power performance always stays below the Betz limit.

show abstract

“…Single wake analysis Considering a single isolated rotor in a uniform flow, Sørensen et al [132] have used the actuator disc concept to analyze wind turbine wake states for laminar conditions; however, most current analyses incorporate turbulence effects. Standard k − ε closure typically underestimates the velocity defect as turbulent diffusion is too high in the wake region.…”

Section: Analysis Of Wind Turbine Wakesmentioning

confidence: 99%

CFD in Wind Energy: The Virtual, Multiscale Wind Tunnel

2010

View full text Add to dashboard Cite

Over the past two decades, computational fluid dynamics and particularly the finite volume method have been increasingly used to predict the performance of wind turbines within their environment. Increases in available computational power has led to the application of RANS-based models to more and more complex flow problems and permitted the use of LES-based models where previously not possible. The following article reviews the development of CFD as applied by the wind energy community from small to large scale: from the flow around 2D airfoils to the flow through an entire wind farm.

show abstract

Analysis of wake states by a full‐field actuator disc model

Cited by 161 publications

References 1 publication

Full Downwind Turbine Simulations Using Actuator Line Method

Full Downwind Turbine Simulations Using Actuator Line Method

Rotor aerodynamic power limits at low tip speed ratio using CFD

CFD in Wind Energy: The Virtual, Multiscale Wind Tunnel

Contact Info

Product

Resources

About