Range Of Wind Speeds Research Articles

An innovative aerodynamic design methodology of wind turbine blade models for wind tunnel real-time hybrid tests based on genetic algorithm

The physical model tests of floating offshore wind turbines (FOWTs) in wave basins cannot simulate the aerodynamic loads accurately. The real-time hybrid model test in wind tunnel provided a better solution to this problem, especially for the simulation of unsteady aerodynamic behaviors. The key to wind tunnel test is the design of aerodynamic thrust-matched blade model. In this paper, an innovative methodology was proposed to design the wind turbine blade models for the wind tunnel tests, based on the genetic algorithm. The design was focused on the aerodynamic thrust performance of blade model to achieve equivalent aerodynamic thrust under different wind speeds. To prove the applicability of this methodology, the DTU 10 MW and NREL 5 MW wind turbine were used for case study and the low-Reynolds airfoil SD7032 was chosen for the aerodynamic design. During the design process, three shape control methods were employed for the twist angles and chords of blades and the effects of these three methods were also compared. The aerodynamic performances of blade models were verified using Aerodyn of FAST, compared to the prototypes. According to the results, the aerodynamic thrust performances of blade models reached good agreement with prototypes in the full wind speed range.

Temperature and Temperature Stress Analysis in Mass Concrete under Cold Environments of Strong Wind and Large Diurnal Temperature Range

Special environmental condition with strong wind and large diurnal temperature range is not conducive for the control of crack development during the curing of mass concrete in the cold environment of Northwest China. In this study, the temperature at four measured points along the vertical profile of a mass concrete was measured over 14 days. Then, a thermal-mechanical model with the optimized initial condition, thermal parameters, boundary conditions, and the effects of rebar on temperature stress of concrete was built. Based on the observations and numerical model, the effects of environmental factor on the peak temperature, temperature fluctuation amplitude, and maximum temperature stress of the mass concrete are analyzed. The result showed that increasing wind speed can reduce the temperature of the concrete, but an opposite result is observed with increase in diurnal temperature range. Moreover, the more obvious diurnal variation of concrete temperature with the increase in wind speed and diurnal temperature range is not conducive to the thermal stability of the structure, especially for horizontal and side surfaces. Accordingly, increasing wind speed and diurnal temperature range will increase the peak temperature stress of the concrete and the overall stress level. Strong wind and large diurnal temperature range significantly increase the temperature stress and its duration for the side surface. The high temperature stress and intensive daily variation of temperature stress at the horizontal surface affect the durability of the concrete material. Therefore, the temperature stresses of the horizontal surface under wind speed levels 3, 4, 5, and 1.25 times large diurnal temperature range easily exceed the tensile strength; then, the temperature crack will appear. Combined with the research results, the temperature control and crack prevention measures are proposed under the condition of ensuring concrete strength. The study will further guide the improvement and optimization of mass concrete construction in an extreme environment.

High Wind Geophysical Model Function Modeling for the HY-2A Scatterometer Using Neural Network

Under low to medium wind speeds and no rainfall, the retrieved vector wind from a scatterometer is accurate and reliable. However, under high wind conditions, the currently used geophysical model function (GMF), such as NSCAT-2, for wind vector retrieval has the disadvantage of overestimating the backscattering coefficient, which leads to a decrease in the quality of the retrieved ocean surface winds. To enhance the wind retrieval precision of the HY-2A scatterometer under high wind conditions, a new GMF for high wind (HW-GMF) is established by using the neural network method based on the backscattering coefficient data of the HY-2A scatterometer combined with the wind speed data of the Special Sensor Microwave Imager (SSM/I) and the Final (FNL) operational global analysis wind direction data from the National Centers for Environmental Prediction (NCEP). The absolute value of the mean deviation between the predicted σ0 by the HW-GMF and the measured σ0 by the HY-2A scatterometer is less than 0.1 dB, indicating that the HW-GMF has high accuracy. To verify the HW-GMF performance, the wind field inversion accuracy of the HW-GMF is compared with that of the NSCAT-2 GMF, a GMF currently used in the data processing of the HY-2A scatterometer. The experimental results show that the deviation between the HW-GMF retrieved wind speed and the SSM/I wind speed is within 2 m/s in the high wind speed range of 15–35 m/s, indicating that the HW-GMF improves the precision of the wind speed inversion of the HY-2A scatterometer under high wind speed conditions.

Influence of Reynolds number on the performance of small horizontal axis wind turbine with fixed speed operation

ABSTRACT The Blade Element Momentum (BEM) theory is most commonly utilized to quickly assess the performance of horizontal axis wind turbine. However, the BEM theory requires the aerodynamic characteristic of the airfoil to evaluate the performance. Generally, the aerodynamic characteristics of airfoil in BEM theory for performance prediction of wind turbine with fixed rotor speed operation is obtained at an approximated fixed Reynolds number which may not accurately correspond to the operating Reynolds number over the blade. In the present work, the performance of a small wind turbine, with fixed rotor speed operation, and considering a range of approximated fixed Reynolds number (i.e., 0.5, 0.75, 1.00, and 1.25 million) and the operational Reynolds number over the blade for the aerodynamic characteristic of the airfoil has been evaluated and compared for a range of wind speeds i.e., 6, 8, 10, and 12 m/s. To incorporate the operational Reynolds number in the study, the aerodynamic characteristics of the airfoil have been mathematically represented as function of Reynolds number and angle of attack using an artificial neural network (ANN)-based model. The results suggest that inadequate Reynolds number consideration can led to high discrepancies up to 18.6% in power coefficient prediction.

A Short-Term Wind Power Forecast Method via XGBoost Hyper-Parameters Optimization

The improvement of wind power prediction accuracy is beneficial to the effective utilization of wind energy. An improved XGBoost algorithm via Bayesian hyperparameter optimization (BH-XGBoost method) was proposed in this article, which is employed to forecast the short-term wind power for wind farms. Compared to the XGBoost, SVM, KELM, and LSTM, the results indicate that BH-XGBoost outperforms other methods in all the cases. The BH-XGBoost method could yield a more minor estimated error than the other methods, especially in the cases of wind ramp events caused by extreme weather conditions and low wind speed range. The comparison results led to the recommendation that the BH-XGBoost method is an effective method to forecast the short-term wind power for wind farms.

A Novel Wind Speed Interval Prediction System Based on Neural Network and Multi-objective Grasshopper Optimization

As a clean energy source, the role of wind power in the energy mix is becoming increasingly important. Reliable and high-quality wind speed prediction results are key to wind energy utilization. The traditional point prediction method cannot effectively analyze the uncertainty of wind speed, and the interval prediction model can provide the possible variation range of wind speed under a certain confidence probability and supply more uncertain information to decision makers. However, the previous interval prediction models generally ignore the random characteristics of capturing wind speed and the importance of objective selection of prediction submodels, leading to poor prediction results. To address these problems, a combined model based on data preprocessing, multi-neural network models, multi-objective optimization, and an improved interval prediction method is proposed. The model is applied to five wind speed forecasting examples in Dalian to test the prediction accuracy, multi-step prediction ability, and universality and generalization ability of the model. The experimental results show that the model proposed in this study is satisfactory for various performance evaluation indexes, has high stability and accuracy, and all the solutions obtained by the model are Pareto optimal solutions. Thus, it provides a reliable reference for the effective utilization of wind energy.

Flight dynamics of aerial vehicle considering time-varying ambient wind

Novel equations of motion for aerial vehicles considering the effect of continuously differentiable time-varying ambient winds are proposed. The equations of motion consist of the aerodynamic angles and the inertial flight path angles as state variables. They cover a large range of ambient wind speeds without any approximation or linearization. Two unique angles of sequential rotations called the path-relative wind angles are proposed to parametrize the difference between the air-relative velocity and the inertial velocity caused by ambient wind terms. Moreover, since the conventional aerodynamic roll angle is no longer well-defined in a wind condition, a compatible modified version is proposed as well. The resulting state equations are structured to form a cascade system, which helps designers interpret the physical and geometrical meaning of individual subsystems and efficiently design a corresponding feedback control law. The model particularly fits motion control problems such as trajectory tracking or path following control of fixed-wing-type aerial vehicles in the presence of time-varying ambient wind. The properties and potential of the proposed formulation are discussed in depth by focusing on the meaning and use of each proposed angle and the wind estimation techniques. Numerical examples demonstrate the usefulness of the proposed model by showing how existing high-performance flight controllers initially developed for windless environments can be reused for windy environments while keeping their overall performance and formulation.

Numerical study of drag force on the UAV tilt and fixed wing model during vertical take off landing

A hybrid vertical take-off landing (VTOL) UAV combines the concepts of fixed-wing and rotary-wing UAV aircraft in one platform while performing in both conventional and vertical take-off landings. This aircraft has a drawback of significant drag force generated due to fixed-wing. Therefore, a Tilt-Wing often utilized to overcome this obstacle whereby it could be adjusted to the vertical and horizontal directions. To enhance the understanding of generated drag force on both wing model, this study was performed by examine the drag characteristic of the VTOL UAV. The simulations were carried out in the wind speed range by 1.4 m/s, 4.17 m/s, and 6.94 m/s. Simulation results showed that the drag of the UAV Hybrid Tilt-Wing and Fixed-Wing increased at the speed of 1.4 m/s to 6.94 m/s while the highest drag value was 177.51 N on a Fixed-Wing UAV aircraft and 1.97 N on a Tilt-Wing UAV aircraft. The result concluded that Tilt-Wing UAV has less drag which was more efficient than fixed-wing.

Study of the temporal variation of offshore wind energy potential in southeast Brazil

Global energy consumption has grown over the years marked by technological development and industrialization. Renewable sources have gained prominence due to climate urgency and international agreements that aim to reduce CO2 emissions across the planet. In this regard, wind energy, already consolidated in the onshore region, has evolved offshore regions. In Brazil, there is a growing interest in offshore wind projects. Many of these projects are currently through the environmental licensing process, mostly in the southeastern region of the country. It is known that this area has a relevant wind energy potential. This area is dynamically dominated by the South Atlantic Subtropical Height, the main meteorological phenomenon in the region, which has been affected by recent changes in the global atmospheric circulation. This work aims to evaluate the temporal variation of offshore wind potential in southeastern Brazil. ERA5 reanalysis hourly outputs from 1979 to 2020 were evaluated through high-level computational tools (python and CDO programming languages and GIS software) and consolidated statistical analysis mechanisms. A general decrease in the frequency of low wind speed records (≤7.5 m·s−1) and a raise in the higher wind speed range (>7.5 m·s−1), mainly related to the intensification and expansion of the South Atlantic Subtropical Height (SASH) over the past 40 years, were observed and affected the estimates of offshore wind potential over the analyzed region. Apart from the coast of São Paulo and the south coast of Rio de Janeiro, there was a consistent increase in the wind power density over decades. The four analyzed points presented an increase of 1.55 W·m−2·y−1 to 1.89 W·m−2·y−1, which corresponds to an increase of 8.2% to 11.2% in the median wind power density.

Evaluation of the global-blockage effect on power performance through simulations and measurements

Abstract. Blockage effects due to the interaction of five wind turbines in a row are investigated through both Reynolds-averaged Navier–Stokes simulations and site measurements. Since power performance tests are often carried out at sites consisting of several turbines in a row, the objective of this study is to evaluate whether the power performance of the five turbines differs from that of an isolated turbine. A number of simulations are performed, in which we vary the turbine inter-spacing (1.8, 2 and 3 rotor diameters) and the inflow angle between the incoming wind and the orthogonal line to the row (from 0 to 45∘). Different values of the free-stream velocity are considered to cover a broad wind speed range of the power curve. Numerical results show consistent power deviations for all five turbines when compared to the isolated case. The amplitude of these deviations depends on the location of the turbine within the row, the inflow angle, the inter-spacing and the power curve region of operation. We show that the power variations do not cancel out when averaging over a large inflow sector (from −45 to +45∘) and find an increase in the power output of up to +1 % when compared to the isolated case under idealised conditions (neutral atmospheric conditions, no vertical wind shear or ground effects). We simulate power performance “measurements” with both a virtual mast and nacelle-mounted lidar and find a combination of power output increase and upstream velocity reduction, which causes an increase of +4 % in the power coefficient under idealised conditions. We also use measurements from a real site consisting of a row of five wind turbines to validate the numerical results. From the analysis of the measurements, we also show that the power performance is impacted by the neighbouring turbines. Compared to when the inflow is perpendicular to the row, the power output varies by +1.8 % and −1.8 % when the turbine is the most downwind and upwind of the line, respectively.

Transport dynamics of SARS-CoV-2 under outdoor conditions.

This study aimed at estimating the transport dynamics of a single severe acute respiratory syndrome corona-virus 2 (SARS-CoV-2)-laden droplet of 1 to 500 μm in diameter at a wind speed from 1 to 4 m/s. Motion dynamics of SARS-CoV-2-laden respiratory droplets under calm or turbulent air conditions were quantified using a combined model. Dalton’s law was implemented to estimate their evaporation. One-factor-at-a-time procedure was applied for the sensitivity analysis of model of deposition velocity. The transport distance of the single virus ranged from 167 to 1120 m as a function of the droplet size, wind speed, and falling time. The evaporation times of the droplets ≤ 3 and ≤ 14 μm in diameter were shorter than their settling times from 1.7 m in height at midnight and midday, respectively. Such droplets remained in the air for about 5 min as the droplet nuclei with SARS-CoV-2. The minimum transport distance of the respiratory droplets of 1–15 μm varied between 8.99 and 142 m at a wind speed range of 1–4 m/s, based on their deposition velocity. With their short transport distance, the larger droplet (30 to 500 μm) was not suspended in the air even under the windy conditions. The deposition velocity was found most sensitive to the droplet diameter. The droplets < 15 μm in diameter completely evaporated at midday and the droplet nuclei with the single virus can travel a minimum distance of 500 m under a horizontal wind speed of 3 m/s.

Wide Bandwidth Wind-Induced Vibration Energy Harvester with an Angle Section Head

A high-performance wind-induced vibration energy harvester with an angle section head is designed. Experimental results show that the harvester has a wide frequency-locked/operating wind speed range. Experiments are carried out for the harvester with different angles and lengths of the angle section head. It is found that the reasonable design of the angle section head can benefit wind energy harvesting. In this study, the widest operating wind speed range of 13.4 m/s (from 6.6 m/s to 20 m/s) is experimentally demonstrated, and the maximum output power is 214.6 μW.

Dilution factor and atmospheric dispersion pattern for Kalpakkam site

Assessment of radiological impact and for planning and preparedness programs, monthly atmospheric dispersion patterns at Kalpakkam have been studied using observed surface meteorological data during 2015–2020. The influence of meteorological factors such as wind speed, wind directions, percent of calm, atmospheric stability, and rainfall on dispersion patterns has been evaluated. The higher wind speed range (&gt;4 m/s) is observed from 11:00 h to 19:00 h with an average wind speed of 4.17 m/s and the highest value observed in the month of May. Extremely stable F category and percent of calm observed to be lowest in the month of June. This study reveals that the high concentration area is toward seaside sectors during the southwest monsoon season from June to September and the remaining months, January to May and October to December, the most probable dispersion toward southwest, South, and North covering land sectors. Wet deposition due to maximum rainfall and more rainy days in the month of November during the northeast monsoon. The study provides site-specific information on dispersion patterns, an essential tool and crucial support for risk management with respect to radiological impact, monitoring and assessment in normal and emergency scenarios of a nuclear facility, and guiding resources for siting and design of the new facility in and around Kalpakkam.

Nonlinear control of wind turbine in above rated wind speed region

Abstract Advanced control of variable speed horizontal wind turbine was considered in the high wind speed range. The aims of control in this region are to limit and stabilize the rotor speed and electrical power to their nominal values, while reducing the fatigue loads acting on the structure. A new nonlinear technique based on combination between sliding mode control and radial basis function neural network control was investigated. The proposed hybrid controller was implemented via MATLAB on a simplified two masses numerical model of wind turbine. By applying the Lyapunov approach, this controller was shown to ensure stability. It was found also to be robust and able to reject the uncertainties associated to system nonlinearities. The obtained results were compared with those provided by an existing controller.

The Effect of Wind Speed on Male Potato Aphid, Macrosiphum euphorbiae, Responses to Primary Host Plant Volatiles and Female Sex Pheromone.

Simple SummaryWe demonstrate that male potato aphids respond more to a combination of volatiles from the host plant on which the species overwinters and the female sex pheromone than to the host plant alone. In both cases, the level of response declines as wind speed increases, but the higher attraction to the combined odour sources is maintained. These findings are discussed within the context of mate location by male aphids, which are insects that have little control over flight direction.In fall, alate males of the potato aphid, Macrosiphum euphorbiae (Thomas), migrate from their summer (secondary) host plants, such as potatoes, to primary host plants, such as roses, where they mate with wingless oviparae who produce the overwintering egg stage. Males are weak fliers and generally walk towards a pheromone source under windy conditions, so we tested the hypothesis that upwind walking behaviour in response to wind velocity would be affected by the volatile cues present. We compared male responses to the odour of a rugosa rose cutting alone and to the combination of host plant volatiles and the female sex pheromone under a range of wind speeds in a laboratory walking bioassay. The proportion of males responding decreased as the wind speed increased, but at all wind velocities, the responses to the combined odours were higher than to the host plant alone. However, at any given wind velocity, the speed at which responding aphids moved was not influenced by the odour source. These findings support the idea that host plant volatiles serve as long-distance cues for males and that the female sex pheromone is used once on the host plant.

Modeling of Wood Surface Ignition by Wildland Firebrands

The probability of structural ignition is dependent both on physical properties of materials and the fire exposure conditions. In this study, the effect of firebrand characteristics (i.e., firebrand size, number of firebrands) on wood ignition behavior was considered. Mathematical modeling and laboratory experiment were conducted to better understand the conditions of wood ignition by a single or group of firebrands with different geometry. This model considers the heat exchange between the firebrands, wood layer and the gas phase, moisture evaporation in the firebrands and the diffusion gases of water vapor in the pyrolysis zone. In order to test and verify the model, a series of experiments to determine probability and conditions for ignition of wood-based materials (plywood, oriented strand board, chipboard) caused by wildland firebrands (pine twigs with a diameter of 6–8 mm and a length of 40 ± 2 mm) were conducted. The experiments investigated the firebrand impact on the wood layer under different parameters, such as firebrand size and quantity, wind speed, and type of wood. The results of experiments showed that the increase in wind speed leads to the increase in probability of wood ignition. Based on the received results, it can be concluded that the ignition curve of wood samples by firebrands is nonlinear and depends on the wind speed and firebrand size as well as their quantity. At the same time, there is no ignition of wood samples in the range of wind speed of 0–1 m/s. The ignition of wood is possible with a decrease in the distance between the firebrands with a decrease in the firebrand length. This result agrees more closely with the model.

Unsteady and nonlinear galloping mechanism of a 3:2 rectangular prism explained with a simplified mathematical model

Direct measurements of galloping self-excited force on a spring-mounted sectional model of a rectangular cross-section with a width-to-depth ratio of 3:2 were carried out for various Scruton numbers and wind speeds. An unsteady and nonlinear mathematical model of the galloping self-excited force is proposed for the acquired forces and validated by the tests. This simplified mathematical model is then used to explain the nonlinearity and unsteadiness in the observed galloping. The evolutions of different aerodynamic damping components during the galloping development were investigated to understand the mechanisms driving the development, the self-limiting behaviour, and the bifurcation of galloping. In the low wind speed range after onset, galloping can spontaneously develop into a limited-cycle-oscillation. In the medium wind speed range beyond onset, the negative linear aerodynamic damping decreases to smaller than the structural damping. So galloping can occur only if the initial excitation is greater than a critical value with which the negative aerodynamic damping is large enough at the initial stage.

Evaluation of Reanalysis and Analysis Datasets against Measured Wind Data for Wind Resource Assessment

The evaluation of reanalysis and analysis data (estimated data) against in-situ measured data is essential to find uncertainties before its use for wind resource assessment. The performance evaluation of four different generations reanalysis datasets (NCEP-CFSR, NCEP-DOE, NCEP-NCAR and JRA-55) and two analysis datasets (NCEP-FNL and NCEP-GFS) was done against measured data for six sites using statistical analysis. A comparison of monthly mean time-series, Weibull probability distribution function and wind rose diagram of measured and estimated data was performed. The MBE and RMSE for wind speed range from −2.18 to 2.01 m/s and 1.34 to 3.00 m/s respectively; whereas MBE and RMSE for wind direction range from −34.34° to 13.90° and 40.58° to 71.28° respectively for six sites using all datasets. NCEP-CFSR data show promising results for most of the sites with the lowest errors and better correlation coefficients. NCEP-CFSR data being the new generation reanalysis having higher spatial resolution show better results compared to other reanalyses and analyses. The reanalysis and analysis wind data can be used as alternative to measured data to assess wind energy potential.

Research on primary frequency modulation control strategy of wind power based on energy storage

As a renewable energy, the uncontrollability of wind energy resources will cause the instability of the power grid. The research on the primary frequency modulation control strategy of wind power has become an urgent problem to be solved. Doubly fed wind power generation is the mainstream generator. The main methods of participating in frequency modulation include inertia control method and load shedding control method. This paper analyzes the doubly fed wind turbine model, analyzes its problems in the process of frequency modulation, and establishes the frequency modulation control strategy of wind turbine in the whole wind speed range by selecting the critical wind speed point. Energy storage technology has the advantages of instantaneous accurate response, safety and reliability. Based on the above, this paper studies the primary frequency modulation of wind power energy storage.

Torque Transmission Law of Wind Turbine Drive System under the Excitation of Uneven Wind Load

A random wind speed time history model based on Weibull distribution is constructed. According to the known mean and variance of wind speed, the time fitting curve of random wind speed is obtained through MATLAB simulation method. According to the wind speed range of the actual operation of the wind turbine, the obtained wind speed curve is transformed, and then according to the obtained relationship between the wind speed of the wind turbine and the input torque, the input time-varying torque of the actual operation of the wind turbine is obtained. Establish the rigid shaft model of the wind turbine gearbox, calculate the gearbox transmission ratios at all levels, and then obtain the torque output curves of the gearbox planetary stage, medium-speed stage, and high-speed stage under random wind speed input to study wind power the torque transmission law of the machine drive system. The ability to better analyse the transmission structure of the gearbox and the torque transmission law of key components has a certain significance for the design and manufacture of the wind turbine transmission chain.