Small-Scale Wind Turbine Testing in Wind Tunnels Under Low Reynolds Number Conditions

Treuren, Kenneth W. Van

doi:10.1115/1.4030617

Cited by 55 publications

(34 citation statements)

References 32 publications

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“…The importance of appropriate aerofoil data for low Reynolds number applications has been well established in the analysis of small wind turbines (24,(30)(31)(32) , and the same holds true for small propellers (9,13,23) . When using blade element analysis methods, aerodynamic data is commonly obtained for a single Reynolds number, taken at 70-75% of the radius (17,33,34) ;…”

Section: Attached-flow Aerodynamic Analysismentioning

confidence: 97%

Blade element momentum theory extended to model low Reynolds number propeller performance

MacNeill

Verstraete

2017

Aeronaut. j.

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Propellers are the predominant propulsion source for small unmanned aerial vehicles. At low advance ratios, large sections of the propeller blade can be stalled, and the Reynolds number faced by each blade can be low. This leads to difficulties in modelling propeller performance, as the aerodynamic models coupled with blade element methods usually only provide aerodynamic data for an assumed aerofoil section, for a small angle-of-attack range and for a single Reynolds number, while rotational effects are often ignored. This is specifically important at low advance ratios, and a consistent evaluation of the applicability of various methods to improve aerodynamic modelling is not available. To provide a systematic appraisal, three-dimensional (3D) scanning is used to obtain the aerofoil sections that make up a propeller blade. An aerodynamic database is formed using each extracted aerofoil section, across a wide range of angles of attack and Reynolds numbers. These databases are then modified to include the effects of rotation. When compared with experimental results, significant improvement in modelling accuracy is shown at low advance ratios relative to a generic blade element-momentum model, particularly for smaller propellers. Notably, when considering small propeller performance, efficiency modelling is improved from within 30% relative to experimental data to within 5% with the use of the extended blade element momentum theory method. The results show that combining Viterna and Corrigan flat plate theory with the Corrigan and Schillings stall delay model consistently yields the closest match with experimental data.

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Section: Attached-flow Aerodynamic Analysismentioning

confidence: 97%

Blade element momentum theory extended to model low Reynolds number propeller performance

MacNeill

Verstraete

2017

Aeronaut. j.

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“…The disadvantages of panel method models for predicting airfoil characteristics at low Reynolds have been addressed by discussing current aspects of wind tunnel testing for wind turbines and its components, as shown by Van Treuren [91]. A different approach is taken by Grasso [92,93], who presents an optimization work with gradient-based methods and a hybrid approach that uses a genetic algorithm along with a gradient method.…”

Section: Numerical Approaches For Aerodynamic Assessmentmentioning

confidence: 99%

Technological and Operational Aspects That Limit Small Wind Turbines Performance

et al. 2020

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Small Wind Turbines (SWTs) are promissory for distributed generation using renewable energy sources; however, their deployment in a broad sense requires to address topics related to their cost-efficiency. This paper aims to survey recent developments about SWTs holistically, focusing on multidisciplinary aspects such as wind resource assessment, rotor aerodynamics, rotor manufacturing, control systems, and hybrid micro-grid integration. Wind resource produces inputs for the rotor’s aerodynamic design that, in turn, defines a blade shape that needs to be achieved by a manufacturing technique while ensuring structural integrity. A control system may account for the rotor’s aerodynamic performance interacting with an ever-varying wind resource. At the end, the concept of integration with other renewable source is justified, according to the inherent variability of wind generation. Several commercially available SWTs are compared to study how some of the previously mentioned aspects impact performance and Cost of Electricity (CoE). Understanding these topics in the whole view may permit to identify both tendencies and unexplored topics to continue expanding SWTs market.

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“…Based on the scaling strategy explained above, the use of wind speeds around 5 m/s and rotor rotation speeds around 400 rpm led to Reynolds numbers in the model blades around Re = 2 × 10 4 , which differ from the Reynolds numbers around Re = 1 × 10 7 from the prototype. It has been stated in the literature, that issues with the behavior of the flow around the rotor blades arise for Reynolds number values below Re = 2 × 10 5 − 5 × 10 5 [31,[37][38][39][40]. To study the flow properties around the model blades at Re = 2 × 10 4 , the polars of a representative blade airfoil, the DU25, were measured in wind tunnel tests using constant section blade models.…”

Section: Scale Effectsmentioning

confidence: 99%

On the Determination of the Aerodynamic Damping of Wind Turbines Using the Forced Oscillations Method in Wind Tunnel Experiments

2019

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The development of wind turbine technology has led to higher and larger wind turbines with a higher sensitivity to dynamic effects. One of these effects is the aerodynamic damping, which introduces favorable damping forces in oscillating wind turbines. These forces play an important role in the turbine lifetime, but have not yet been studied systematically in detail. Consequently, this paper studies the plausibility of determining the aerodynamic damping of wind turbines systematically through wind tunnel experiments using the forced oscillation method. To this end, a 1:150 scale model of a prototype wind turbine has been fabricated considering Reynolds number effects on the blades through XFOIL calculations and wind tunnel measurements of airfoil 2D-section models. The resulting tower and wind turbine models have been tested for different operation states. The tower results are approximate and show low aerodynamic damping forces that can be neglected on the safe side. The measured aerodynamic damping forces of the operating turbine are compared to existing analytic approaches and to OpenFAST simulations. The measured values, although generally larger, show good agreement with the calculated ones. It is concluded that wind tunnel forced oscillations experiments could lead to a better characterization of the aerodynamic damping of wind turbines.

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Small-Scale Wind Turbine Testing in Wind Tunnels Under Low Reynolds Number Conditions

Cited by 55 publications

References 32 publications

Blade element momentum theory extended to model low Reynolds number propeller performance

Blade element momentum theory extended to model low Reynolds number propeller performance

Technological and Operational Aspects That Limit Small Wind Turbines Performance

On the Determination of the Aerodynamic Damping of Wind Turbines Using the Forced Oscillations Method in Wind Tunnel Experiments

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