Rotation Of Wind Turbine Blades Research Articles

Understanding fatality patterns and sex ratios of Brazilian free-tailed bats (Tadarida brasiliensis) at wind energy facilities in western California and Texas

Background Operation of wind turbines has resulted in collision fatalities for several bat species, and one proven method to reduce these fatalities is to limit wind turbine blade rotation (i.e., curtail turbines) when fatalities are expected to be highest. Implementation of curtailment can potentially be optimized by targeting times when females are most at risk, as the proportion of females limits the growth and stability of many bat populations. The Brazilian free-tailed bat (Tadarida brasiliensis) is the most common bat fatality at wind energy facilities in California and Texas, and yet there are few available data on the sex ratios of the carcasses that are found. Understanding the sex ratios of fatalities in California and Texas could aid in planning population conservation strategies such as informed curtailment. Methods We used PCR to determine the sex of bat carcasses collected from wind energy facilities during post-construction monitoring (PCM) studies in California and Texas. In California, we received samples from two locations within the Altamont Pass Wind Resource Area in Alameda County: Golden Hills (GH) (n = 212) and Golden Hills North (GHN) (n = 312). In Texas, we received samples from three wind energy facilities: Los Mirasoles (LM) (Hidalgo County and Starr County) (n = 252), Los Vientos (LV) (Starr County) (n = 568), and Wind Farm A (WFA) (San Patricio County and Bee County) (n = 393). Results In California, the sex ratios of fatalities did not differ from 50:50, and the sex ratio remained stable over the survey years, but the seasonal timing of peak fatalities was inconsistent. In 2017 and 2018, fatalities peaked between September and October, whereas in 2019 and 2020 fatalities peaked between May and June. In Texas, sex ratios of fatalities varied between locations, with Los Vientos being female-skewed and Wind Farm A being male-skewed. The sex ratio of fatalities was also inconsistent over time. Lastly, for each location in Texas with multiple years studied, we observed a decrease in the proportion of female fatalities over time. Discussion We observed unexpected variation in the seasonal timing of peak fatalities in California and differences in the sex ratio of fatalities across time and facility location in Texas. In Texas, proximity to different roost types (bridge or cave) likely influenced the sex ratio of fatalities at wind energy facilities. Due to the inconsistencies in the timing of peak female fatalities, we were unable to determine an optimum curtailment period; however, there may be location-specific trends that warrant future investigation. More research should be done over the entirety of the bat active season to better understand these trends in Texas. In addition, standardization of PCM studies could assist future research efforts, enhance current monitoring efforts, and facilitate research on post-construction monitoring studies.

Numerical simulation of flow-induced noise generation and propagation of a floating offshore wind turbine with prescribed pitch motion

It is important to evaluate flow-induced noise emitted due to operations of floating offshore wind turbines since noise pollution can damage the environments of seabirds and aquatic species. This paper studies the aerodynamic and aeroacoustic performance of a laboratory three-blade wind turbine model with an airfoil profile of NREL S826. The wind turbine blade rotation motion is coupled with the prescribed pitch motion of the floating offshore wind power platform. The influence of prescribed pitch motions on the noise generated by wind turbine blades and noise propagation was discussed. Adopting the computational fluid dynamics (CFD) method, the aerodynamic noise field on a blade is simulated by the improved delayed detached eddy simulation (IDDES) model and Ffowcs Williams–Hawkings (FW-H) acoustic analogy. The overset grid technique is adopted to simulate the six degrees of freedom (DoFs) motions of the floating offshore wind turbine model. The sound source distributions on blades for noise generation are obtained, and the flow-induced noise propagation characteristics are analyzed. It is found that the influence of the pitch amplitude and frequency on the flow-induced noise field as well as the wake vortex characteristics should not be neglected.

Mitigation Measures for Windfarm Effects on Radar Systems

Windfarms can have a significant impact on radar systems, especially air surveillance radar. This is because it is usually designed to show only moving targets and cancel out stationary objects. However, the rotation of wind turbine blades can be detected by radar as a false flight or target. Clutter or interference caused by windfarms can reduce radar sensitivity in critical regions, making real targets disappear. This could in turn affect the deployment of windfarms and lead to the cancellation of future renewable energy projects and plans. This paper presents the different strategies and techniques used to mitigate the windfarm impact on radar systems. Precisely, we aim throughout this article to classify the main currently adopted approaches, view the recent trends and research directions in this field, and try to trace the advantages and drawbacks along with the challenges of deploying such schemes.

Simulation and Performance Test Giromill Type Wind Turbine; Case Study Muara Enim, South Sumatra, Indonesia

This research examines the dynamic load resistance of the Giromill type wind turbine to the variable wind speed, which is converted to the value of the force received by the wind turbine blades. The analysis was carried out numerically using Autodesk Inventor Professional 2019 software. The variations in wind speed used were 2.5 m/s with a force value of 0.195 N for the Giromill turbine, at a speed of 3.5 m/s with a force value of 0.274 N, at 4.5 m /s with a Force value of 0.352 N and a wind speed of 5.5 m/s with a force rating of 0.430 N. From the simulation results using the Autodesk Inventor Pro 2019 software, the effect of gravitational force is greater than the wind force in, so stress analysis is mainly caused by gravity while the wind force has no significant impact. The simulation results also have a characteristic that the higher the wind speed, the lower the stress value. In addition to the dynamic load simulation, the author also tries to implement the Giromill wind turbines in Muara Enim district, South Sumatra, Indonesia. The wind turbine blade rotation will be faster, and the Wind Generator will produce a greater voltage if it is supported by sufficient wind speed.

Aerodynamic Characteristics of a Single Airfoil for Vertical Axis Wind Turbine Blades and Performance Prediction of Wind Turbines

The design of wind turbines requires a deep insight into their complex aerodynamics, such as dynamic stall of a single airfoil and flow vortices. The calculation of the aerodynamic forces on the wind turbine blade at different angles of attack (AOAs) is a fundamental task in the design of the blades. The accurate and efficient calculation of aerodynamic forces (lift and drag) and the prediction of stall of an airfoil are challenging tasks. Computational fluid dynamics (CFD) is able to provide a better understanding of complex flows induced by the rotation of wind turbine blades. A numerical simulation is carried out to determine the aerodynamic characteristics of a single airfoil in a wide range of conditions. Reynolds-averaged Navier–Stokes (RANS) equations and large-eddy simulation (LES) results of flow over a single NACA0012 airfoil are presented in a wide range of AOAs from low lift through stall. Due to the symmetrical nature of airfoils, and also to reduce computational cost, the RANS simulation is performed in the 2D domain. However, the 3D domain is used for the LES calculations with periodical boundary conditions in the spanwise direction. The results obtained are verified and validated against experimental and computational data from previous works. The comparisons of LES and RANS results demonstrate that the RANS model considerably overpredicts the lift and drag of the airfoil at post-stall AOAs because the RANS model is not able to reproduce vorticity diffusion and the formation of the vortex. LES calculations offer good agreement with the experimental measurements.

Analysis of Wind Turbine Aging through Operation Data Calibrated by LiDAR Measurement

This study analyzed the performance decline of wind turbine with age using the SCADA (Supervisory Control And Data Acquisition) data and the short-term in situ LiDAR (Light Detection and Ranging) measurements taken at the Shinan wind farm located on the coast of Bigeumdo Island in the southwestern sea of South Korea. Existing methods have generally attempted to estimate performance aging through long-term trend analysis of a normalized capacity factor in which wind speed variability is calibrated. However, this study proposes a new method using SCADA data for wind farms whose total operation period is short (less than a decade). That is, the trend of power output deficit between predicted and actual power generation was analyzed in order to estimate performance aging, wherein a theoretically predicted level of power generation was calculated by substituting a free stream wind speed projecting to a wind turbine into its power curve. To calibrate a distorted wind speed measurement in a nacelle anemometer caused by the wake effect resulting from the rotation of wind-turbine blades and the shape of the nacelle, the free stream wind speed was measured using LiDAR remote sensing as the reference data; and the nacelle transfer function, which converts nacelle wind speed into free stream wind speed, was derived. A four-year analysis of the Shinan wind farm showed that the rate of performance aging of the wind turbines was estimated to be −0.52%p/year.

Power generation of small wind turbine: Under high-speed operation

Mechanical energy is produced through the rotation of wind turbine blades by air that converts mechanical energy into electrical energy. Wind turbines are usually designed for particular applications, and design characteristics may vary depending on the area of use. The variety of applications is reflected on the size of turbines and their infrastructures. Wind turbine performance may be enhanced by analyzing the small horizontal axis wind turbine (SHAWT) under high-wind-speed operation. This work analyzes the implementation of the SHAWT and investigates its performance in simulation and real life. The power performance of the SHAWT, which largely depends on the real structure of the rotor geometry and aerodynamic test, was simulated using ANSYS Fluent software at different wind speeds of up to 33.33 m/s (120 km/h) to numerically investigate actual turbine operation. Dynamic mesh and user-defined function (UDF) were used to revolve the rotor turbine via wind. Simulation results were further validated by experimental data, and good matching was achieved. A car alternator was formed and used as a small horizontal wind turbine to reduce energy production cost. Consequently, the alternator-based turbine system was found to be a low-cost solution for the exploitation of wind energy.

Small Horizontal Axis Wind Turbine under High Speed Operation: Study of Power Evaluation

Mechanical energy is produced through the rotation of wind turbine blades by air that convert the mechanical energy into electrical energy. Wind turbines are usually designed to be use for particular applications and design characteristics may vary depending on the area of use. The variety of applications is reflected on the size of turbines and their infrastructures, however, performance enhancement of wind turbine may start by analyzing the small horizontal axis wind turbine (SHAWT) under high wind speed operation. This paper analyzes the implementations of SHAWT turbines and investigates their performance in both simulation and real life. Depending on the real structure of the rotor geometry and aerodynamic test, the power performance of the SHAWT was simulated using ANSYS-FLUENT software at different wind speed up to 33.33 m/s (120km/h) in order to numerically investigate the actual turbine operation. Dynamic mesh and user define function (UDF) was used for revolving the rotor turbine via wind. Simulation results were further validated by experimental data and hence good matching was yielded. And for reducing the energy producing cost, car alternator was formed to be used as a small horizontal wind turbine. As a result, alternator-based turbine system was found to be a low-cost solution for exploitation of wind energy.

Wind turbine clutter signature for maritime UHF radar

Scattering signal variability due to wind turbine blade rotation usually degrades the performance of nearby radio systems, which severely inhibits the development of wind power installation. As for the maritime ultra-high frequency (UHF) radar, the wind turbine clutter (WTC) may mask small targets and increase the error of sea state measurement. In order to solve the problem from the radar side, a complete understanding of the WTC signature is needed. Using the data of a 10-day in-field experiment on the coast of Fujian Province of China, this paper studies the empirical characteristics of WTC in maritime UHF radar from several signal processing domains, including the time, frequency, space, and polarization domains. Several methods for detection and mitigation of WTC are proposed which are based on the unique characteristics of WTC, such as the time-periodicity, frequency expansion, space concentration, and much stronger magnitude than the ocean-scattered signals when both the transmitting and receiving antennas are horizontally polarized.

Impact of wind turbine blade rotation on the lightning strike incidence – A theoretical and experimental study using a reduced-size model

The influence of wind turbine blade rotation on the lightning behavior is not sufficiently studied. The original theoretical analysis and experimental investigation, whose most important segments are described in this paper, should enable a better understanding of this phenomenon. The tests were conducted in the high-voltage laboratory, applying the up-and-down method for determination of the 50% flashover standard switching voltage. The impulse voltage waves were applied between the specially designed arching electrode and/or the several rod electrodes at discrete positions along the insulating arching cylinder and the blades of a reduced-size wind turbine model, driven by a frequency controlled motor. A lightning protection system in the form of receptors on the tips of the blades was examined. According to the theory of similarity the paper discusses the characteristics of direct atmospheric discharges for the several typical rotational speeds of the wind turbine. It was concluded that the number of direct lightning strikes in the zone of the air termination system on the blades is decreasing due to the rotation of the blades.

Experimental Research on the Influence of Wind Turbine Blade Rotation on the Characteristics of Atmospheric Discharges

The experimental research, whose most important segments are described in this paper, is one of the first attempts to determine the influence of wind turbine blade rotation on likelihood of getting struck by lightning. The tests were conducted in the high-voltage laboratory, applying the up-and-down method for determination of the 50% flashover standard switching voltage. The impulse voltage waves were applied between the specially de signed arching electrode and the blades of a reduced-size wind turbine model, driven by a frequency controlled motor. Two types of lightning protection systems and the case of absent protection system were examined. According to the theory of similarity this pa per discusses the characteristics of direct atmospheric discharges for the following typical rotational speeds of the wind turbine: w = 0 r/min (when the wind turbine is idle), w = 250 r/min (for the winds of moderate strength), and w = 400 r/min (rated rotor speed).

Audible low‐frequency wind turbine sound.

To date a large fraction of research on wind turbine sound has been directed at the audible spectrum. Rotation of wind turbine blades is a primary cause of the cyclic broad‐band sound that is characteristic of wind turbines. Auto‐correlations of measured wind turbine sounds exhibit distinct, periodic “low frequency” pulses. The pulse duration is but a fraction of the blade passage period, with energy content of the order of 20–40% of the overall mean square pressure. Analytical decomposition of the low‐frequency pulses reveals line spectra whose components diminish relatively slowly. The spectrum levels of the frequency components above 20 Hz are sufficiently high to be audible under favorable ambient conditions. This hypothesis was tested by generating and listening to various possible pressure time histories that share the shape of the low‐frequency pulses as measured by auto‐correlations. When propagation effects such as scattering are accounted for, the relative phase shifts suffered by the higher frequency components result in an audible swoosh.