Analysis of the Impact of Leading Edge Surface Degradation on Wind Turbine Performance

This paper describes a brief overview of main issues related to atmospheric ice accretion on wind turbines installed in cold climate region. Icing has significant effects on wind turbine performance particularly from aerodynamic and structural integrity perspective, as ice accumulates mainly on the leading edge of the blades that change its aerodynamic profile shape and effects its structural dynamics due to added mass effects of ice. This research aims to provide an overview and develop further understanding of the effects of atmospheric ice accretion on wind turbine blades. One of the operational challenges of the wind turbine blade operation in icing condition is also to overcome the process of ice shedding, which may happen due to vibrations or bending of the blades. Ice shedding is dangerous phenomenon, hazardous for equipment and personnel in the immediate area.

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Aerodynamic Analysis of an Airfoil With Leading Edge Pitting Erosion

Journal of Solar Energy Engineering ◽

10.1115/1.4037380 ◽

2017 ◽

Vol 139 (6) ◽

Cited By ~ 2

Author(s):

Yan Wang ◽

Ruifeng Hu ◽

Xiaojing Zheng

Keyword(s):

Wind Turbine ◽

Indirect Effects ◽

Leading Edge ◽

Aerodynamic Performance ◽

Navier Stokes ◽

Distribution Area ◽

Navier Stokes Equation ◽

Turbine Performance ◽

Wind Turbine Airfoil ◽

Cfd Method

Leading edge erosion is a considerable threat to wind turbine performance and blade maintenance, and it is very imperative to accurately predict the influence of various degrees of erosion on wind turbine performance. In the present study, an attempt to investigate the effects of leading edge erosion on the aerodynamics of wind turbine airfoil is undertaken by using computational fluid dynamics (CFD) method. A new pitting erosion model is proposed and semicircle cavities were used to represent the erosion pits in the simulation. Two-dimensional incompressible Reynolds-averaged Navier–Stokes equation and shear stress transport (SST) k–ω turbulence model are adopted to compute the aerodynamics of a S809 airfoil with leading edge pitting erosions, where the influences of pits depth, densities, distribution area, and locations are considered. The results indicate that pitting erosion has remarkably undesirable influences on the aerodynamic performance of the airfoil, and the critical pits depth, density, and distribution area degrade the airfoil aerodynamic performance mostly were obtained. In addition, the dominant parameters are determined by the correlation coefficient path analysis method, results showed that all parameters have non-negligible effects on the aerodynamics of S809 airfoil, and the Reynolds number is of the most important, followed by pits density, pits depth, and pits distribution area. Meanwhile, the direct and indirect effects of these factors are analyzed, and it is found that the indirect effects are very small and the parameters can be considered to be independent with each other.

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Brief communication: Nowcasting of precipitation for leading-edge-erosion-safe mode

Wind Energy Science ◽

10.5194/wes-5-977-2020 ◽

2020 ◽

Vol 5 (3) ◽

pp. 977-981 ◽

Cited By ~ 1

Author(s):

Anna-Maria Tilg ◽

Charlotte Bay Hasager ◽

Hans-Jürgen Kirtzel ◽

Poul Hummelshøj

Keyword(s):

Liquid Phase ◽

Wind Turbine ◽

Turbine Blades ◽

Leading Edge ◽

Wind Turbine Blades ◽

Spatio Temporal ◽

The Impact ◽

Theoretical Considerations ◽

Mode A ◽

Precipitation Events

Abstract. Leading-edge erosion (LEE) of wind turbine blades is caused by the impact of hydrometeors, which appear in a solid or liquid phase. A reduction in the wind turbine blades' tip speed during defined precipitation events can mitigate LEE. To apply such an erosion-safe mode, a precipitation nowcast is required. Theoretical considerations indicate that the time a raindrop needs to fall to the ground is sufficient to reduce the tip speed. Furthermore, it is described that a compact, vertically pointing radar that measures rain at different heights with a sufficiently high spatio-temporal resolution can nowcast rain for an erosion-safe mode.

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Uncertainty Quantification of Leading Edge Erosion Impacts on Wind Turbine Performance

Journal of Physics Conference Series ◽

10.1088/1742-6596/1618/5/052082 ◽

2020 ◽

Vol 1618 ◽

pp. 052082

Author(s):

David C. Maniaci ◽

Carsten Westergaard ◽

Alan Hsieh ◽

Joshua A. Paquette

Keyword(s):

Wind Turbine ◽

Uncertainty Quantification ◽

Leading Edge ◽

Turbine Performance

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The Impact of Ice Formation on Wind Turbine Performance and Aerodynamics

Journal of Solar Energy Engineering ◽

10.1115/1.4003187 ◽

2011 ◽

Vol 133 (1) ◽

Cited By ~ 33

Author(s):

S. Barber ◽

Y. Wang ◽

S. Jafari ◽

N. Chokani ◽

R. S. Abhari

Keyword(s):

Wind Energy ◽

Wind Turbine ◽

Swiss Alps ◽

Test Facility ◽

Ice Formation ◽

Predictive Tool ◽

Lower Altitude ◽

Turbine Performance ◽

The Impact ◽

Power Curves

Wind energy is the world’s fastest growing source of electricity production; if this trend is to continue, sites that are plentiful in terms of wind velocity must be efficiently utilized. Many such sites are located in cold, wet regions such as the Swiss Alps, the Scandinavian coastline, and many areas of China and North America, where the predicted power curves can be of low accuracy, and the performance often deviates significantly from the expected performance. There are often prolonged shutdown and inefficient heating cycles, both of which may be unnecessary. Thus, further understanding of the effects of ice formation on wind turbine blades is required. Experimental and computational studies are undertaken to examine the effects of ice formation on wind turbine performance. The experiments are conducted on a dynamically scaled model in the wind turbine test facility at ETH Zurich. The central element of the facility is a water towing tank that enables full-scale nondimensional parameters to be more closely matched on a subscale model than in a wind tunnel. A novel technique is developed to yield accurate measurements of wind turbine performance, incorporating the use of a torquemeter with a series of systematic measurements. These measurements are complemented by predictions obtained using a commercial Reynolds-Averaged Navier–Stokes computational fluid dynamics code. The measured and predicted results show that icing typical of that found at the Guetsch Alpine Test Site (2330 m altitude) can reduce the power coefficient by up to 22% and the annual energy production (AEP) by up to 2%. Icing in the blade tip region, 95–100% blade span, has the most pronounced effect on the wind turbine’s performance. For wind turbines in more extreme icing conditions typical of those in Bern Jura, for example, icing can result in up to 17% losses in AEP. Icing at high altitude sites does not cause significant AEP losses, whereas icing at lower altitude sites can have a significant impact on AEP. Thus, the classification of icing is a key to the further development of prediction tools. It would be advantageous to tailor blade heating for prevention of ice buildup on the blade’s tip region. An “extreme” icing predictive tool for the project development of wind farms in regions that are highly susceptible to icing would be beneficial to wind energy developers.

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Effect of Flow Inclination on Wind Turbine Performance

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4007323 ◽

2012 ◽

Vol 134 (12) ◽

Cited By ~ 10

Author(s):

Christina Tsalicoglou ◽

Sarah Barber ◽

Ndaona Chokani ◽

Reza S. Abhari

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Complex Terrain ◽

Wake Flow ◽

Test Facility ◽

Power Coefficient ◽

Incoming Flow ◽

Turbine Performance ◽

The Impact ◽

Blade Element

This work examines the effect of flow inclination on the performance of a stand-alone wind turbine and of wind turbines operating in the wakes of upstream turbines. The experimental portion of this work, which includes performance and flowfield measurements, is conducted in the ETH dynamically-scaled wind turbine test facility, with a wind turbine model that can be inclined relative to the incoming flow. The performance of the wind turbine is measured with an in-line torquemeter, and a 5-hole steady-state probe is used to detail the inflow and wake flow of the turbine. Measurements show that over a range of tip-speed ratios of 4–7.5, the power coefficient of a wind turbine with an incoming flow of 15 deg inclination decreases on average by 7% relative to the power coefficient of a wind turbine with a noninclined incoming flow. Flowfield measurements show that the wake of a turbine with an inclined incoming flow is deflected; the deflection angle is approximately 6 deg for an incoming flow with 15 deg inclination. The measured wake profiles are used as inflow profiles for a blade element momentum code in order to quantify the impact of flow inclination on the performance of downstream wind turbines. In comparison to the case without inclination in the incoming flow, the combined power output of two aligned turbines with incoming inclined flow decreases by 1%, showing that flow inclination in complex terrain does not significantly reduce the energy production.

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Mitigating impact of spatial variance of turbulence in wind energy applications

Wind Energy Science ◽

10.5194/wes-5-439-2020 ◽

2020 ◽

Vol 5 (2) ◽

pp. 439-450

Author(s):

Jonas Kazda ◽

Jakob Mann

Keyword(s):

Wind Turbine ◽

Random Error ◽

Wind Farm ◽

Second Order ◽

Mitigation Measures ◽

Order Moment ◽

Spatial Variance ◽

Turbine Performance ◽

The Difference ◽

The Impact

Abstract. For the first time an analytical solution for the quantification of the spatial variance of the second-order moment of correlated wind speeds was developed in this work. The spatial variance is defined as random differences in the sample variance of wind speed between different points in space. The approach is successfully verified using simulation and field data. The impact of the spatial variance on three selected applications relevant to the wind energy sector is then investigated including mitigation measures. First, the difference of the second-order moment between front-row wind turbines of Lillgrund wind farm is investigated. The variance of the difference ranges between 25 % and 48 % for turbulence intensities ranging from 7 % to 10 % and a sampling period of 10 min. It is thus suggested to use the second-order moment measured at each individual turbine as input to flow models of wind farm controllers in order to mitigate random error. Second, the impact of the spatial variance of the measured second-order moment on the verification of wind turbine performance is investigated. Misalignment between the mean wind direction and the line connecting the meteorological mast and wind turbine is observed to result in an additional random error in the observed second-order moment of wind speed. In the investigated conditions the random error was up to 34 %. Such a random error adds uncertainty to the turbulence intensity-based classification of the fatigue loads and power output of a wind turbine. To mitigate the random error, it is suggested to either filter the measured data for low angles of misalignment or quantify wind turbine performance using the ensemble-averaged measurements of the same wind conditions. Third, the verification of sensors in wind farms was investigated with respect to the impact of distant reference measurements. In the case of a misalignment between the wind direction and the line connecting sensor and reference, an increased random error will hamper the comparison of the measured second-order moments. The suggested mitigation measures are equivalent to those for the verification of turbine performance.

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Numerical Modeling of the Effects of Leading-Edge Erosion and Trailing-Edge Damage on Wind Turbine Loads and Performance

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4048451 ◽

2020 ◽

Vol 142 (11) ◽

Author(s):

Francesco Papi ◽

Lorenzo Cappugi ◽

Sebastian Perez-Becker ◽

Alessandro Bianchini

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Prolonged Exposure ◽

Leading Edge ◽

Future Generation ◽

Operating Conditions ◽

Wind Speeds ◽

And Performance ◽

Lift And Drag ◽

The Impact

Abstract Wind turbines operate in challenging environmental conditions. In hot and dusty climates, blades are constantly exposed to abrasive particles that, according to many field reports, cause significant damages to the leading edge. On the other hand, in cold climates similar effects can be caused by prolonged exposure to hail and rain. Quantifying the effects of airfoil deterioration on modern multi-MW wind turbines is crucial to correctly schedule maintenance and to forecast the potential impact on productivity. Analyzing the impact of damage on fatigue and extreme loading is also important to improve the reliability and longevity of wind turbines. In this work, a blade erosion model is developed and calibrated using computational fluid dynamics (CFD). The Danmarks Tekniske Universitet (DTU) 10 MW Reference Wind Turbine is selected as the case study, as it is representative of the future generation wind turbines. Lift and Drag polars are generated using the developed model and a CFD numerical setup. Power and torque coefficients are compared in idealized conditions at two wind speeds, i.e., the rated speed and one below it. Full aero-servo-elastic simulations of the turbine are conducted with the eroded polars using NREL's BEM-based code OpenFAST. Sixty-six 10-min simulations are performed for each stage of airfoil damage, reproducing operating conditions specified by the IEC 61400-1 power production DLC-group, including wind shear, yaw misalignment, and turbulence. Aeroelastic simulations are analyzed, showing maximum decreases in CP of about 12% as well as reductions in fatigue and extreme loading.

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INVESTIGATION OF TORQUE GENERATION CAPABILITY OF MIXED FLOW TURBINE UNDER STEADY STATE CONDITIONS

Jurnal Teknologi ◽

10.11113/jt.v79.11924 ◽

2017 ◽

Vol 79 (7-3) ◽

Author(s):

M. A. S. Izaiddin ◽

A. F. Mustaffa ◽

M. H. Padzillah

Keyword(s):

Mass Flow ◽

Leading Edge ◽

Maximum Efficiency ◽

Blade Surface ◽

Mixed Flow ◽

Factors Affecting ◽

Turbine Performance ◽

Radial Turbine ◽

Torque Generation ◽

Edge Surface

A mixed flow turbine is a type of turbine that is used mostly in turbocharger engine for vehicle. The ability of this turbine in obtain maximum efficiency on a wider operating range makes it more favorable compared to axial turbine and radial turbine. In this project, one of the factors affecting turbine performance which is torque has been studied using simulation. The simulation is then being run by varying the mass flow supply to the turbine. In this simulation, torque generation has been identified and plot on the entire blade surface. This torque generation capability is then been compared between 0.25 kg/s, 0.45 kg/s and 0.65 kg/s mass flow. From the simulation, the torque generated is founded to fluctuate along the turbine blade surface. Besides, the torque generated at the leading edge and trailing edge surface are negative. The magnitude of torque generated increases, as the mass flow increased. At the mid span of the blade, torque generated at 0.25 kg/s, 0.45 kg/s and 0.65 kg/s is -3.73 X 10-3Nm, 4.33 X 10-3Nm, and 11.8 X 10-3Nm respectively.

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Effect of moisture percentage on the wind turbine performance

Al-Kitab Journal for Pure Sciences ◽

10.32441/kjps.v2i1.145 ◽

2018 ◽

Vol 2 (1) ◽

Author(s):

Suad Danook ◽

Kamal Tawfeeq ◽

Esraa Mansoor

Keyword(s):

Kinetic Energy ◽

Wind Turbine ◽

Electric Energy ◽

Energy System ◽

Alternative Source ◽

Dry Air ◽

Turbine Performance ◽

Wind Energy System ◽

Moisture Percentage ◽

The Impact

This paper incorporates the utilization of the wind energy system as an alternative source for Traditional source of energy, where it has been studied convert the kinetic energy in the wind to electric energy and the impact of humidity which effect on the density of air and the density of dry air is higher from humid. So the humid air meaning lower density then lower power from wind turbine.

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