Comparison of Mann Turbulence and atmospheric turbulence as inflow conditions on a wind turbine in large-eddy simulations (LES)

2021 ◽  
Author(s):  
Linus Wrba ◽  
Antonia Englberger
Keyword(s):  
Wind Turbine ◽  
Atmospheric Surface Layer ◽  
Turbine Blades ◽  
Potential Temperature ◽  
Large Eddy Simulations ◽  
Wind Turbine Blades ◽  
Large Eddy ◽  
The Impact ◽  
Inflow Conditions ◽  
Blade Element

<p>This study deals with different inflow conditions on wind-turbines in LES in order to analyse the impact on the wake. The wind turbine regarded in this study has a hub height of 57.19 m while the radius of the blade measures 40m. Furthermore, the blade element momentum method (BEM) is used to calculate the development forces of the wind turbine blades on the flow. First, the syntheticly generated turbulence of a Mann[1] box generator is considered. Second, atmospheric boundary layer simulations from Englberger and Dörnbrack (2018) are applied as inflow conditions for the three wind components and the potential temperature to calculate the wake of the wind turbine. The distribution of turbulent kinetic energy in eddys of different sizes is worked out in their energy spectrum.The inflow conditions represent the -5/3 Kolmogorov spectrum. The wake characteristics are evaluated for both inflow datasets and the arising differences are discussed in this study</p><div><br><div> <p>[1] Mann, J. (1994). The spatial structure of neutral atmospheric surface-layer turbulence. Journal of fluid mechanics 273</p> </div> </div><div><br><div> <p> </p> </div> </div>

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

2020 ◽  
Vol 5 (3) ◽  
pp. 977-981 ◽  
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.

scholarly journals Stochastic Model for Aerodynamic Force Dynamics on Wind Turbine Blades in Unsteady Wind Inflow

2015 ◽  
Vol 10 (4) ◽  
Author(s):  
M. R. Luhur ◽  
J. Peinke ◽  
M. Kühn ◽  
M. Wächter
Keyword(s):  
Stochastic Model ◽  
Wind Turbine ◽  
Aerodynamic Force ◽  
Turbine Blades ◽  
Stochastic Approach ◽  
Simulation Software ◽  
Dynamic Stall ◽  
Wind Turbine Blades ◽  
Full Field ◽  
Blade Element

The paper presents a stochastic approach to estimate the aerodynamic forces with local dynamics on wind turbine blades in unsteady wind inflow. This is done by integrating a stochastic model of lift and drag dynamics for an airfoil into the aerodynamic simulation software AeroDyn. The model is added as an alternative to the static table lookup approach in blade element momentum (BEM) wake model used by AeroDyn. The stochastic forces are obtained for a rotor blade element using full field turbulence simulated wind data input and compared with the classical BEM and dynamic stall models for identical conditions. The comparison shows that the stochastic model generates additional extended dynamic response in terms of local force fluctuations. Further, the comparison of statistics between the classical BEM, dynamic stall, and stochastic models' results in terms of their increment probability density functions (PDFs) gives consistent results.

Development of wireless bird collision monitoring system using 0-3 piezoelectric composite sensor on wind turbine blades

2017 ◽  
Vol 29 (17) ◽  
pp. 3426-3435
Author(s):  
Sang-Hyeon Kang ◽  
Lae-Hyong Kang
Keyword(s):  
Wind Turbine ◽  
Monitoring System ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Wind Farms ◽  
Clean Energy ◽  
Piezoelectric Composite ◽  
Collision Rate ◽  
Wind Turbine Blades ◽  
The Impact

Over the past several decades, wind turbines have been established as one of the promising renewable energy systems for safe and clean energy collection. In order to collect more energy efficiently, the size of wind turbines has been increased and many wind farms have been constructed. Wind farms generate lots of energy, but they cause several side effects, such as noise and a threat to wildlife. It is reported that the bird collision rate of a wind turbine ranges from 0.01 to 23 annually. It is more serious in the case of rare and endangered birds. In order to monitor the effect on birds in wind farms, researchers have developed remote sensing technology for a detection apparatus using heat and radar. In addition, paint color and other variables have been studied regarding their effects on the collision rate. However, the existing methods are passive ways to prevent bird collision or just monitor bird conditions. Therefore, in this study, we propose a bird collision monitoring system that can detect where the bird collision occurred, which will aid in rescuing the birds. If the wind turbine blade has its own ability to capture an impact signal, the impact location can be easily detected, and the birds can be rescued. For this purpose, piezoelectric paint was applied to the wind turbine blades used in this study. The piezoelectric paint is also known as 0-3 piezoelectric composite, which is composed of piezoelectric particles and polymer resin. It is sensitive to high-frequency signals such as impacts, so it is suitable for monitoring bird collision signals. In order to amplify and transmit the impact signal from the rotating blade to a stationary base, a wireless transmission device using a ZigBee module and signal conditioning circuit was also installed. Through lab-scale tests, it was confirmed that this bird collision monitoring system shows a 100% bird collision detection rate.

scholarly journals Bondline Thickness Effects on Damage Tolerance of Adhesive Joints Subjected to Localized Impact Damages: Application to Leading Edge of Wind Turbine Blades

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7526
Author(s):  
Amrit Shankar Verma ◽  
Nils Petter Vedvik ◽  
Zhen Gao ◽  
Saullo G. P. Castro ◽  
Julie J. E. Teuwen
Keyword(s):  
Wind Turbine ◽  
Damage Tolerance ◽  
Turbine Blades ◽  
Impact Loads ◽  
Wind Turbine Blades ◽  
Failure Loads ◽  
Leading Edges ◽  
Bondline Thickness ◽  
The Impact ◽  
Impact Damages

The leading edges of wind turbine blades are adhesively bonded composite sections that are susceptible to impact loads during offshore installation. The impact loads can cause localized damages at the leading edges that necessitate damage tolerance assessment. However, owing to the complex material combinations together with varying bondline thicknesses along the leading edges, damage tolerance investigation of blades at full scale is challenging and costly. In the current paper, we design a coupon scale test procedure for investigating bondline thickness effects on damage tolerance of joints after being subjected to localized impact damages. Joints with bondline thicknesses (0.6 mm, 1.6 mm, and 2.6 mm) are subjected to varying level of impact energies (5 J, 10 J, and 15 J), and the dominant failure modes are identified together with analysis of impact kinematics. The damaged joints are further tested under tensile lap shear and their failure loads are compared to the intact values. The results show that for a given impact energy, the largest damage area was obtained for the thickest joint. In addition, the joints with the thinnest bondline thicknesses displayed the highest failure loads post impact, and therefore the greatest damage tolerance. For some of the thin joints, mechanical interlocking effects at the bondline interface increased the failure load of the joints by 20%. All in all, the coupon scale tests indicate no significant reduction in failure loads due to impact, hence contributing to the question of acceptable localized damage, i.e., damage tolerance with respect to static strength of the whole blade.

Analysis of Aerodynamic Performance for Wind Turbine Based on Amended Calculation of BEM Theory

2012 ◽  
Vol 608-609 ◽  
pp. 775-780
Author(s):  
De Tian ◽  
Shuo Ming Dai ◽  
Si Liu ◽  
Ning Bo Wang
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Aerodynamic Performance ◽  
Wind Turbine Blades ◽  
Thrust Coefficient ◽  
Load Distributions ◽  
Design Software ◽  
Turbine Design ◽  
Bem Theory ◽  
Blade Element

Effects of tip losses, hub losses, amended attack angle, and amended thrust coefficient are taken into consideration to analyze aerodynamic performance of wind turbine blades based on the blade element momentum (BEM) theory. Based on amended calculation of BEM theory, a program code is developed by software named Matlab. Using a 1500kW wind turbine as an example, aerodynamic information, performance coefficients and blade load distributions are calculated. Compared with the well-known international wind power design software called Garrad Hassan (GH) Bladed, the results have good consistency, which further verifies amendments to the model algorithms and accuracy of the calculation. As a result, the amended calculation of BEM theory can reflect blade aerodynamic performance characteristics under actual operating condition, which has good reference and practicality for the wind turbine design and evaluation.

scholarly journals Modelling Rain Drop Impact of Offshore Wind Turbine Blades

2012 ◽  
Author(s):  
M. H. Keegan ◽  
D. H. Nash ◽  
M. M. Stack
Keyword(s):  
Wind Turbine ◽  
Impact Damage ◽  
Turbine Blades ◽  
Leading Edge ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wind Turbine Blades ◽  
Erosion Testing ◽  
Software Modelling ◽  
The Impact

The effects of rain and hail erosion and impact damage on the leading edge of offshore wind turbine blades have been investigated. A literature review was conducted to establish the effects of exposure to these conditions and also to investigate the liquid impact phenomena and their implications for leading edge materials. The role of Explicit Dynamics software modelling in simulating impact events was then also established. Initial rain impact modelling is then discussed with the results showing good agreement with theoretical predictions both numerically and with respect to the temporal and spatial development of the impact event. Future development of the rain model and a proposed hail model are then detailed. Planned rain impact and erosion testing work is addressed which will be used to validate, inform and compliment the ongoing modelling efforts.

Flexible and Vibration Characteristics Simulation for the Large Megawatt Size Wind Turbine Blades

2011 ◽  
Vol 217-218 ◽  
pp. 363-367
Author(s):  
Xu Dong Wang ◽  
Li Cun Wang ◽  
Xian Ming Zhang ◽  
Jun Feng
Keyword(s):  
Wind Turbine ◽  
Wind Power ◽  
Turbine Blades ◽  
Vibration Characteristics ◽  
Wind Turbine Blades ◽  
Fatigue Lifetime ◽  
Aeroelastic Model ◽  
Blade Tip ◽  
Important Significance ◽  
Blade Element

In the development of new large megawatt size wind turbines, aerodynamic and structural reserch is interesting and important for study wind turbine performace and boost the development of wind power. In this paper, the aerodynamic and aeroelastic characteristic of blades is investigated and presented based on Blade Element Momentum and Hamilton theory. Then the flexible characteristics of balde is researched with the aerodynamic and aeroelastic model of the rotor. The flapwise and edgewise displacements, velocities and accelerations of blade tip are simulated and plotted to validate the model which is presented in this paper. The results have very important significance to investigate the vibration and fatigue lifetime of the wind turbine blades.

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