Evaluation of the lifting line vortex model approximation for estimating the local blade flow fields in horizontal-axis wind turbines

Sant, Tonio; Campo, Vanessa del; Micallef, Daniel; Ferreira, Carlos

doi:10.1063/1.4942785

Cited by 8 publications

(7 citation statements)

References 19 publications

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“…The LineAve method also provides reasonable results, even with a low number of circle nodes and small radii. Significantly lower r c i r c than recommended by Sant et al seem to be possible since |Δ α | a v e is generally low. This might be connected to the averaging procedure.…”

Section: Resultsmentioning

confidence: 99%

“…Similar to the SHS1 method, a minimum radius has to be kept regarding the point vortex modeling. Sant et al recently determined the error in the flow field of a lifting‐line code compared with PIV measurements and a panel model. They recommend distances in the order of 2.2 c for an error below 10% regarding the PIV measurements.…”

Section: Line Average Methods (Lineave)mentioning

confidence: 99%

“…Similar to the SHS1 method, a minimum radius has to be kept regarding the point vortex modeling. Sant et al 17 regarding the PIV measurements. In the present study, radii from 0.8c to 2.2c are tested.…”

Section: Line Average Methods (Lineave)mentioning

confidence: 99%

“…recommended by Sant et al17 seem to be possible since |Δα| ave is generally low. This might be connected to the averaging procedure.…”

mentioning

confidence: 94%

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Extracting the angle of attack on rotor blades from CFD simulations

et al. 2018

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In today's wind energy research, comparisons of low‐fidelity aerodynamic models with CFD simulations are common practice. While the approach for loads with respect to the rotor‐plane coordinate system such as distributed driving force or thrust is straightforward, a comparison of aerodynamic characteristics is more challenging. The radial distributions of lift, drag, and moment coefficient depend on the local angle of attack and inflow velocity, which cannot be directly determined from the flow field. It requires the elimination of the influence of the rotor blade's bound circulation and also involves the step from a three‐dimensional flow field to quantities, which depend on the blade radius. The present investigation analyzes 4 different approaches to determine the angle of attack and inflow velocity from three‐dimensional rotor simulations. In addition to 3 existing methods, a new line average technique is presented. It eliminates the effect of bound circulation by averaging along a closed shape, which is symmetric to the quarter‐chord point. All methods are assessed in cases with successively increasing complexity. The observed discrepancies are assigned to a different consideration of trailing and shed vortices. The line average approach was found to be a valuable alternative to existing approaches especially in unsteady cases and regarding the outer or tip sections of the rotor blade.

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Section: Resultsmentioning

confidence: 99%

Section: Line Average Methods (Lineave)mentioning

confidence: 99%

Section: Line Average Methods (Lineave)mentioning

confidence: 99%

“…recommended by Sant et al17 seem to be possible since |Δα| ave is generally low. This might be connected to the averaging procedure.…”

mentioning

confidence: 94%

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Extracting the angle of attack on rotor blades from CFD simulations

et al. 2018

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“…These two phenomena cause convergence problems. To avoid these numerical problems, some vortex core models based on the Lamb-Oseen vortex model [26], Ramasamy and Leishman vortex model [27], Vatistas vortex model [28] and β-Vatistas vortex model [29,30] have been applied in a FVW model. In our recent work, we compared the effects of the β-Vatistas model and Lamb-Oseen model in the FVW model [29] and further studied the application [30] of the β-Vatistas model.…”

Section: Velocity Induced By the Near Wakementioning

confidence: 99%

A Simplified Free Vortex Wake Model of Wind Turbines for Axial Steady Conditions

Wang

Yuan

et al. 2018

Applied Sciences

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A simplified free vortex wake (FVW) model called the vortex sheet and ring wake (VSRW) model was developed to rapidly calculate the aerodynamic performance of wind turbines under axial steady conditions. The wake in the simplified FVW model is comprised of the vortex sheets in the near wake and the vortex rings, which are used to replace the helical tip vortex filament in the far wake. The position of the vortex ring is obtained by the motion equation of its control point. Analytical formulas of the velocity induced by the vortex ring were introduced to reduce the computational time of the induced velocity calculation. In order to take into account both accuracy and calculation time of the VSRW model, the length of the near wake was cut off at a 120 • wake age angle. The simplified FVW model was used to calculate the aerodynamic load of the blade and the wake flow characteristic. The results were compared with measurement results and the results from the full vortex sheet wake model and the tip vortex wake model. The computational speed of the simplified FVW model is at least an order of magnitude faster than other two conventional models. The error of the low-speed shaft torque obtained from the simplified FVW model is no more than 10% relative to the experiment at most of wind speeds. The normal and tangential force coefficients obtained from the three models agree well with each other and with the measurement results at the low wind speed. The comparison indicates that the simplified FVW model predicts the aerodynamic load accurately and greatly reduces the computational time. The axial induction factor field in the near wake agrees well with the other two FVW models and the radial expansion deformation of the wake can be captured.

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