Experimental assessment of an active L-shaped tab for dynamic stall control

Zanotti, Alex; Gibertini, G.

doi:10.1016/j.jfluidstructs.2017.11.010

Cited by 14 publications

(7 citation statements)

References 28 publications

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“…The uncertainty could be divided into systematic uncertainty and random uncertainty. Because this experiment used precision instruments, the systematic uncertainty error had no significant impact and could be easily overcome by a large number of samples [35]. Additionally, according to the relevant reference [36], the random uncertainty could be averaged through repeated measurements to ensure the accuracy of the data.…”

Section: Experimental Methodologymentioning

confidence: 99%

Experimental Study on the Effect of the Blade Tip Distance on the Power and the Wake Recovery with Small Multi-Rotor Wind Turbines

Gong

Pan

Yang

et al. 2023

JMSE

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In order to investigate the output power and wake velocity of small multi-rotor wind turbines compared to single-rotor wind turbines, which operate in the same swept area at various blade tip distances, this paper used the wind tunnel test method to examine single-rotor wind turbines with diameter D of 0.4 m and 0.34 m corresponding to the triple-rotor wind turbines and double-rotor wind turbines with a single rotor diameter D of 0.24 m, respectively. The experimental results indicated that, without rotation speed control, the triple-rotor wind turbine produced more power than the single-rotor wind turbine with an equivalent swept area and that the output power tended to rise initially and then fall as the distance between each rotor increased. Moreover, the power increase reached a maximum of 8.4% at the 0.4D blade tip distance. In terms of wake measurement, triple-rotor wind turbines had smaller wake losses and faster recovery rates than single-rotor wind turbines. The smaller the blade tip distance, the earlier the wake merged and fused and the faster the recovery rate. In designing small multi-rotor wind turbines, the above discussion can serve as a guide.

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Section: Experimental Methodologymentioning

confidence: 99%

Experimental Study on the Effect of the Blade Tip Distance on the Power and the Wake Recovery with Small Multi-Rotor Wind Turbines

Gong

Pan

Yang

et al. 2023

JMSE

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“…Uncertainty analysis of the pressure measurements in the present study was considered by using the standard deviation as the error bars, which consisted of suggestions from similar experiments [26,27]. By this method, the uncertainties can be solved by a large number of samples and multiple measurements for the Gurney flap [36].…”

Section: Data Processing Methodologymentioning

confidence: 99%

“…Acceptable repeatability of the phase averaged values of lift coefficients were observed. The fluctuations near the stall region of downstroke motion, as shown in the right top with phase averaged values, and standard deviations were caused by the randomness of large vortical structures [26]. Hence, measurements were performed several times, and the subsequent analyses of the measured data were all averaged.…”

Section: Surface Pressure Characteristicsmentioning

confidence: 99%

“…The study results mentioned that increasing the reduced frequency and oscillation amplitude could improve the maximum lift coefficient and the lift curve slope. Zanotti and Gibertini [26] tested the aerodynamic characteristics of Gurney flaps with active form installed on pitching airfoils in a wind tunnel. The research stated that the lift coefficients of the airfoil could be increased in the upstroke motion, and the Gurney flap retracted in the downstroke motion to reduce the possibility of stall flutter.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Study of a Gurney Flap on a Pitching Wind Turbine Airfoil under Turbulent Flow Conditions

Yang

Wang

et al. 2022

JMSE

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The present work aimed to investigate the aerodynamic characteristics of a pitching wind turbine airfoil with a Gurney flap under turbulent inflow. Experiments were carried out for the DTU-LN221 offshore wind turbine airfoil under different turbulence levels at Reynolds number 105 order of magnitude by replacing the grilles in the wind tunnel. The dynamic stall characteristics were analyzed by measuring surface pressure and near-wake flow field. The pressure results demonstrated that with the increase of turbulence intensity, the differences in lift hysteresis loops between baseline airfoil and flapped airfoil became smaller. With the turbulence intensity from 0.5% to 10.18%, the maximum lift increment of the Gurney flap decreased from 14.32% to 4.34% (i.e., 0–20° pitching oscillation). In a more extensive range of oscillation, the capability for the lift-improvement dropped down a bit more (i.e., 0–25°). A brief aerodynamic damping analysis indicated that the Gurney flap was more stable in turbulent conditions than the baseline airfoil. Besides, hysteresis loops of the wake were analyzed to compare the difference between the flapped airfoil and the baseline airfoil. Unlike the studies of static airfoils, the results may help better understand the dynamic characteristics of offshore wind turbines with Gurney flaps for practical situations.

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“…Troldborg (2005) was able to use the TEF motion to counteract the oscillating pitch motion and obtain smooth lift data on the airfoil. Zanotti and Gibertini (2018) investigated the use of an active Gurney flap for dynamic stall control on a pitching airfoil and found that the flap was capable of reducing the amplitude of dynamic stall. Feszty et al (2004) and Shehata et al (2018) showed that pulsing the TEF was capable of improving wind turbine rotor performance and removing negative effects of dynamic stall.…”

Section: Introductionmentioning

confidence: 99%

Deep dynamic stall and active aerodynamic modification on a S833 airfoil using pitching trailing edge flap

Samara

Johnson

2020

Wind Engineering

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Due to the dynamic nature of the wind resource, wind turbine blades are subjected to significant variation in flow parameters, such as the angle of attack ([Formula: see text]). In some cases, the occurrence of dynamic stall on wind turbine blades causes load fluctuation which leads to material fatigue that tends to decrease the life span of the blades. In this study, the influence of a trailing edge flap on dynamic stall effects is investigated at high [Formula: see text] typical of wind turbines but atypical elsewhere. Pitching of the trailing edge flap was found to have a significant impact on the dynamic stall hysteresis loops responsible for the load fluctuation. Frequency analysis showed that the trailing edge flap was capable of reducing the cyclic fluctuation in the coefficient of lift and root bending moment by at least 26% and 24%, respectively. These results are a significant contribution toward understanding the advantages of using trailing edge flaps and how implementing them will reduce wind turbine blade load fluctuations.

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Experimental assessment of an active L-shaped tab for dynamic stall control

Cited by 14 publications

References 28 publications

Experimental Study on the Effect of the Blade Tip Distance on the Power and the Wake Recovery with Small Multi-Rotor Wind Turbines

Experimental Study on the Effect of the Blade Tip Distance on the Power and the Wake Recovery with Small Multi-Rotor Wind Turbines

Experimental Study of a Gurney Flap on a Pitching Wind Turbine Airfoil under Turbulent Flow Conditions

Deep dynamic stall and active aerodynamic modification on a S833 airfoil using pitching trailing edge flap

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