A study on rotational augmentation using CFD analysis of flow in the inboard region of the MEXICO rotor blades

Guntur, Srinivas; Sørensen, Niels N.

doi:10.1002/we.1726

Cited by 34 publications

(28 citation statements)

References 22 publications

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“…This effect delays the stall onset and enhances the lift force as compared to non-rotating blades operating at the same AoA. The Himmelskamp effect, also known as stall delay or rotational augmentation, has been studied by many authors both experimentally (Schreck and Robinson, 2002;Sicot et al, 2008;Ronsten, 1992) and numerically (Guntur and Sørensen, 2014;Herráez et al, 2014;Schreck et al, 2007), although it still remains far from being well understood and characterized. It mainly affects the blade root region and is known to be closely related to the existence of spanwise flows in the boundary layer.…”

Section: Spanwise Flows and Himmelskamp Effectmentioning

confidence: 99%

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Detailed analysis of the blade root flow of a horizontal axis wind turbine

et al. 2016

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Abstract. The root flow of wind turbine blades is subjected to complex physical mechanisms that influence significantly the rotor aerodynamic performance. Spanwise flows, the Himmelskamp effect, and the formation of the root vortex are examples of interrelated aerodynamic phenomena that take place in the blade root region. In this study we address those phenomena by means of particle image velocimetry (PIV) measurements and Reynolds-averaged Navier-Stokes (RANS) simulations. The numerical results obtained in this study are in very good agreement with the experiments and unveil the details of the intricate root flow. The Himmelskamp effect is shown to delay the stall onset and to enhance the lift force coefficient C l even at moderate angles of attack. This improvement in the aerodynamic performance occurs in spite of the negative influence of the mentioned effect on the suction peak of the involved blade sections. The results also show that the vortex emanating from the spanwise position of maximum chord length rotates in the opposite direction to the root vortex, which affects the wake evolution. Furthermore, the aerodynamic losses in the root region are demonstrated to take place much more gradually than at the tip.

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Section: Spanwise Flows and Himmelskamp Effectmentioning

confidence: 99%

“…Centrifugal force: the centrifugal force that acts on the bottom of the boundary layer (i.e. the region where the flow is not detached from the surface) pushes the flow towards the tip (Du and Selig, 1999;Lindenburg, 2003;Guntur and Sørensen, 2014).…”

Section: The Source Of the Spanwise Flowsmentioning

confidence: 99%

Detailed analysis of the blade root flow of a horizontal axis wind turbine

et al. 2016

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“…Therefore, we assume that comparing 2D and 3D characteristics is an acceptable method for assessing the role of the rotational effects. This is also the most common way to do it [10,14,16,18,20,29,30,34,38].…”

Section: The Mexico Experimentsmentioning

confidence: 99%

“…In a later work, Schreck et al studied the same turbine using RANS with the kω − SST turbulence model and ascribed the rotational effects to stationary vortical structures located on the upper blade surface [19]. Very recently, Guntur and Sørensen [20] studied the MEXICO turbine with RANS and the kω model, observing that on rotating blades there is a postponement of the separation point. Furthermore, it was concluded that the AoA at which separation is initiated is higher in 3D compared with 2D.…”

Section: Introductionmentioning

confidence: 99%

Insight into Rotational Effects on a Wind Turbine Blade Using Navier–Stokes Computations

Herráez

Stoevesandt²,

Peinke

2014

Energies

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Rotational effects are known to influence severely the aerodynamic performance of the inboard region of rotor blades. The underlying physical mechanisms are however far from being well understood. The present work addresses this problem using Reynolds averaged Navier-Stokes computations and experimental results of the MEXICO (Model Experiments in Controlled Conditions) rotor. Four axisymmetric inflow cases with wind speeds ranging from pre-stall to post-stall conditions are computed and compared with pressure and particle image velocimetry (PIV) experimental data, obtaining, in general, consistent results. At low angles of attack, the aerodynamic behavior of all of the studied blade sections resembles the one from the corresponding 2D airfoils. However, at high angles of attack, rotational effects lead to stall delay and/or lift enhancement at inboard positions. Such effects are shown to occur only in the presence of significant radial flows. Interestingly, the way in which rotational effects influence the aerodynamics of the MEXICO blades differs qualitatively in certain aspects from the descriptions found in the literature about this topic. The presented results provide new insights that are useful for the development of advanced and physically-sound correction models.

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“…This is to be expected although the reason is under discussion (Herráez et al, 2016) at the blade root area and has been attributed to span-wise pressure gradients (Schreck et al, 2010) and centrifugal forces on the boundary layer (Guntur and Sørensen, 2014). SFA values increase as λ decreases.…”

mentioning

confidence: 85%

Flow angle measurement of a yawed turbine and comparison to models

Gallant

Johnson

2017

Preprint

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Abstract. The torque generated by a wind turbine blade is dependent on several parameters, one of which is the angle of attack.Several models for predicting the angle of attack in yawed conditions have been proposed in the literature, but there is a lack of experimental data to use for direct validation.To address this problem, experiments were conducted under controlled conditions at the University of Waterloo Wind Generation Research Facility using a 3.4 m diameter test turbine. A five-hole pressure probe was installed in a modular 3D printed These five-hole probe measurements were also used to characterize the upstream flow profile. Wind speeds determined using the five-hole probe measurements are presented and are in agreement with measurements obtained in the wind facility during testing. The quality of results indicates the potential of the developed instrument for wind turbine measurements.

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A study on rotational augmentation using CFD analysis of flow in the inboard region of the MEXICO rotor blades

Cited by 34 publications

References 22 publications

Detailed analysis of the blade root flow of a horizontal axis wind turbine

Detailed analysis of the blade root flow of a horizontal axis wind turbine

Insight into Rotational Effects on a Wind Turbine Blade Using Navier–Stokes Computations

Flow angle measurement of a yawed turbine and comparison to models

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