Three-dimensional Wind Research Articles

Aero-elastic response of transmission line system subjected to downburst wind: Validation of numerical model using experimental data

At the University of Western Ontario (UWO), numerical tools represented in semi-closed form solution for the conductors and finite element modeling of the lattice tower were developed and utilized significantly to assess the behavior of transmission lines under downburst wind fields. Although these tools were validated against other finite element analyses, it is essential to validate the findings of those tools using experimental data. This paper reports the first aeroelastic test for a multi-span transmission line under simulated downburst. The test has been conducted at the three-dimensional wind testing facility, the WindEEE dome, located at the UWO. The experiment considers various downburst locations with respect to the transmission line system. Responses obtained from the experiment are analyzed in the current study to identify the critical downburst locations causing maximum internal forces in the structure (i.e., potential failure modes), which are compared with the failure modes obtained from the numerical tools. In addition, a quantitative comparison between the measured critical responses obtained from the experiment with critical responses obtained from the numerical tools is also conducted. The study shows a very good agreement between the critical configurations of the downburst obtained from the experiment compared to those predicted previously by different numerical studies. In addition, the structural responses obtained from the experiment and those obtained from the numerical tools are in a good agreement where a maximum difference of 16% is found for the mean responses and 25% for the peak responses.

Combined optimization of continuous wind turbine placement and variable hub height

This paper aims to systematically study the wind farm optimization with the continuous selection of wind turbine placement (using Cartesian coordinates) and wind turbine hub height (restrained among a predefined range). Two case studies are performed. The first case involves an ideal two-dimensional (i.e., flat terrain) wind farm, and the other is a three-dimensional wind farm with real terrain altitudes. The schemes of simultaneously optimizing the wind farm layout and wind turbine hub heights applying the simplified and augmented PARK wake model are established for the ideal and real wind farm cases, respectively. The results show that applying different wind turbine hub heights for the wind farm layout optimization yields significant improvement: up to a 0.2 MW increase in total power and a 2% increase of the wind farm efficiency for the ideal wind farm. However, for the real wind farm the effectiveness of applying different wind turbine hub heights varies depending on the number of turbines installed. With less number of turbines installed, the impact of varying hub heights is small. However, significant improvements can be achieved as the number of turbines increases. With 39 wind turbines, the wind farm cost of energy can be reduced by $15000 per megawatt and the wind farm efficiency can increase by up to 0.2%. Given the nameplate capacity and the lifespan of wind farm project, the resulting effect on total energy production can be significant and thus improve the competitiveness of wind power exploitation.

Evaluation of the nondeterministic dynamic structural response of three-dimensional wind turbine steel towers

This investigation develops an analysis methodology aiming at the evaluation of the nondeterministic dynamic structural response of typical wind turbine supporting steel towers. The study was centered on the evaluation of the dynamic behaviour of an actual MM92 wind turbine tower of 2.1 MW Wind Class III IEC2a and mounted on an 80-m-high steel tower. The developed finite element modelling calibration was based on comparisons to experimental data related to an experimental modal analysis acquired on the wind tower structure. The wind tower dynamic structural response was investigated under gravity loads + rotor forces + nondeterministic wind dynamic loads. The present analysis has shown that the wind turbine first bending vibration mode represents the main peak of energy transfer of the dynamic structural response and this energy transfer becomes larger as the wind velocity is increased. Based on the von Mises stress distribution, it was verified that some regions of the wind tower started to yield but there is no plastic hinge formation in the wind tower sections.

Multi-scale simulation of time-varying wind fields for Hangzhou Jiubao Bridge during Typhoon Chan-hom

This paper proposes a downscaled simulation framework aimed to resolve micro-scale wind velocity fields around a targeted site influenced by a typhoon. The framework is consisting of three procedures: (1) typhoon evolution reanalysis by the Advanced Hurricane Weather Research and Forecasting (AHW) model, (2) the large-eddy simulation (LES) coupled in the Weather Research and Forecasting (WRF) model (WRF-LES), and (3) stochastic generation of local turbulent flows. The framework incorporates high-resolution Geographic Information System (GIS) data to capture the effects of urbanization and complex local topography. The framework is applied to carry out multi-scale simulation of time-varying wind fields for Hangzhou Jiubao Bridge during Typhoon Chan-hom in 2015. The AHW model is able to resolve the three-dimensional wind velocity fields of Chan-hom, which provide the initial and lateral boundary conditions for further downscaled simulation over Hangzhou area. The kinematic simulation (KS) method due to its computational efficiency is employed to generate zero-mean turbulent wind velocities, which are then combined with the outputs of WRF-LES mode to reproduce full turbulent wind velocity fields for Jiubao Bridge. The simulation results of real application demonstrate the effectiveness and applicability of the framework, which provides a cross-scale simulation capability of reproducing typhoon wind fields.

A Variation Method for Retrieval of Three-Dimensional Wind Field by Bistatic Doppler Weather Radar Network

A variational method for the retrieval of 3D wind field by bistatic Doppler radar network is developed, and its performance is evaluated. This bistatic Doppler weather radar network consists of one X-band Doppler radar and one passive low-gain bistatic receiver. To allow for measurement error, this method uses the two radial velocities as weak constraints and uses the continuity equation as a strong constraint in a cost function. Improvements are brought to the classical upward integration of the continuity equation, using a weighted combination of upward and downward integrations and its adjoint. The wind field retrieval experiments are carried out by the actual observation data, and compared with the wind filed retrieved by the two Doppler radars. The results show that the wind field is very close, and the synchronous observation technology of the bistatic Doppler radar network is reasonable, which has the potential application in real-time detection of 3D wind field, especially for detecting near surface wind field.

Development and application of a simulator for offshore wind turbine blades installation

In an offshore environment, offshore wind energy resources are more available and stable, but the investment cost is much higher than that of onshore wind. The installation cost is a crucial factor of the investment. With the increasing number of planned and approved offshore wind farms, offshore wind turbine installation and relevant operations have received tremendous attention. Therefore, expediting the turbine-structure mating operations through a higher level of automation in offshore wind turbine installations may provide important economic benefits. To achieve a higher automation level and reduce the weather waiting time during the installation of offshore wind turbines, a flexible simulation-verification framework with high fidelity is needed. However, state-of-the-art wind turbine numerical analysis code is neither convenient nor open enough for applications concerning the design and verification of control algorithms. MATLAB/Simulink is among the most widely utilized numerical platforms by control engineers and researchers. This paper describes the development of a modularized blade installation simulation toolbox for the purpose of control design in MATLAB/Simulink. The toolbox can be used to simulate several blade installation configurations, both onshore and offshore. The paper presents the key features and equations of the different modules, exemplified by a single blade installation operation. Code-to-code verification results are presented and discussed with both quasi-steady wind and three-dimensional turbulent wind field.

Study on an innovative three-dimensional wind turbine wake model

In this paper, to help handle wind farm optimization problems, an original analytical three-dimensional wind turbine wake model is presented and validated. Compared with existing analytical wake models, the presented wake model also considers the wind variation in the height direction, which is more accurate and closer to the reality. The wake model is based on the flow flux conservation law, and it assumes that the wind deficit downstream of a wind turbine is Gaussian-shaped. The derivation process is described in detail. The wake model is validated by published wind tunnel measurement data at both horizontal and vertical sections. Detailed relative errors are analyzed: the relative errors are mostly within 5% in the horizontal profile validation and within 3% in the vertical profile validation. Based on the wake model, a series of prediction results from multiple views and at different positions are demonstrated. From the predictions, the three-dimensional wake model is effective in describing the spatial distribution of wind velocity. It makes a theoretical contribution to the single wake study, and it is also meaningful to the further study of multiple wakes. Because height is considered in the three-dimensional wake model, the model can be used to optimize wind turbine hub heights and to solve more wind farm layout optimization problems, which will further contribute to increasing the energy output and decreasing the cost of energy.

Chiral anisotropic magnetoresistance of ferromagnetic helices

We investigate the anisotropic magnetoresistance (AMR) of ferromagnetic CoNi microhelices fabricated by electrodeposition and laser printing. We find that the geometry of the three-dimensional winding determines a characteristic angular and field-dependence of the AMR due to the competition between helical shape anisotropy and an external magnetic field. Moreover, we show that there is an additional contribution to the AMR that scales proportionally to the applied current and depends on the helical chirality. We attribute this contribution to the self-magnetic field induced by the current, which modifies the orientation of the magnetization relative to the current flow along the helix. Our results underline the interest of three-dimensional curved geometries to tune the AMR and realize tubular magnetoresistive devices.

New Setup of the UAS ALADINA for Measuring Boundary Layer Properties, Atmospheric Particles and Solar Radiation

The unmanned research aircraft ALADINA (Application of Light-weight Aircraft for Detecting in situ Aerosols) has been established as an important tool for boundary layer research. For simplified integration of additional sensor payload, a flexible and reliable data acquisition system was developed at the Institute of Flight Guidance, Technische Universität (TU) Braunschweig. The instrumentation consists of sensors for temperature, humidity, three-dimensional wind vector, position, black carbon, irradiance and atmospheric particles in the diameter range of ultra-fine particles up to the accumulation mode. The modular concept allows for straightforward integration and exchange of sensors. So far, more than 200 measurement flights have been performed with the robustly-engineered system ALADINA at different locations. The obtained datasets are unique in the field of atmospheric boundary layer research. In this study, a new data processing method for deriving parameters with fast resolution and to provide reliable accuracies is presented. Based on tests in the field and in the laboratory, the limitations and verifiability of integrated sensors are discussed.

An investigation into the characteristics of inertia gravity waves in the upper troposphere/lower stratosphere using a 205 MHz wind profiling radar

ABSTRACTA stratosphere-troposphere (ST) wind profiler at 205 MHz is operational at the Advanced Centre for Atmospheric Radar Research (10.04N; 76.33E), Cochin University of Science and Technology, India. This profiler provides accurate three-dimensional wind profiles for an altitude range of 315 m to 20 km. In this paper, we present the characteristics of inertia-gravity waves (IGWs) observed in the upper troposphere/lower stratosphere from uninterrupted observations of wind profiles taken from 22–27 October 2016. The propagation properties of the waves were derived using hodograph analysis. The intrinsic period of the IGWs is found to be 28.75 hours, and the vertical and horizontal wavelengths of the wave are 3.74 and 1221 km, respectively. The hodograph shows a clockwise rotation of the ellipse, which indicates an upward propagation of energy from the upper troposphere to the lower stratosphere. These waves were observed in conjunction with a persistent deep depression over the Bay of Bengal.

Technical Details of a Novel Wind Profiler Radar at 205 MHz

AbstractThe Cochin University of Science and Technology (CUSAT), Cochin, India, hosts the world’s first 205-MHz stratosphere–troposphere (ST) wind profiler radar. This radar constitutes 619 three-element Yagi–Uda antennas with a power aperture product of 1.6 × 108 Wm2 and is capable of providing accurate three-dimensional wind profiles for an altitude range of 315 m–20 km. The system description and its first time validation and results from some of the radar’s potential applications are being presented. The radar wind profiles have been validated against collocated GPS–radiosonde measurements during the summer monsoon of 2016. The radar and radiosonde profiles show very good correlation with coefficients of 0.99 and 0.93 for zonal and meridional winds, respectively. The standard deviation of the radar measurements with respect to radiosonde measurements is found to be 1.85 m s−1 for zonal wind and 1.66 m s−1 for meridional wind. Moreover, the radar also detects echoes from the ionosphere. The ST radar at Cochin (10.04°N, 76.33°E; 40 m MSL) is an ideal observational facility, located in the tropics, for understanding the processes of the Indian summer monsoon at the region of its onset, which is expected to enhance science’s knowledge of monsoon dynamics.

Three-dimensional wind turbine positioning using Gaussian particle swarm optimization with differential evolution

This paper studies the optimization of wind turbine positioning with multiple hub heights on flat terrain using the Gaussian Particle Swarm Optimization (GPSO) with differential evolution. The hub height of each turbine within the wind farm is added to the optimization variables, and the horizontal coordinates and the hub heights of all the turbines are optimized simultaneously. The objective is to minimize the ratio of cost and power product. Three typical wind cases are employed to test the effectiveness of the present method. Numerical results reveal the necessity of the three-dimensional (3D) optimization. By comparing the optimized solutions with the ones by the greedy algorithm and the genetic algorithm, it is concluded that the present method is able to produce optimized solutions with lower cost per product and higher power output in most circumstances, especially in complicated situations.

Mitigation of offshore wind turbine responses under wind and wave loading: Considering soil effects and damage

The present paper studies the mitigation of monopile offshore wind turbines subjected to wind and wave loading. Soil effects (SE) and damage are considered. A semiactive tuned mass damper (STMD) capable of retuning its natural frequency and damping property in real time is utilized to mitigate the nacelle/tower top dynamic response. Based on the Euler–Lagrangian equation, an analytical model of the wind turbine coupled with an STMD is established wherein the interaction between the blades and the tower is modeled. Wind turbulence is generated via mapping a three-dimensional wind field profile onto the rotating blades. Aerodynamic loading is computed using the blade element momentum method where the Prandtl's tip loss factor and the Glauert correction are considered. Wave loading is computed using Morison's equation together with the strip theory. The National Renewable Energy Laboratory monopile 5-MW baseline wind turbine model is employed to examine the performance of the STMD. It is found that the SE and damage presence in the foundation or/and the tower can change the dominant frequency, thereby rendering the conventional TMD detuned and ineffective. In comparison, the STMD retuned in real time by the proposed algorithm can mitigate the nacelle/tower and foundation response more effectively with a smaller stroke. Results indicate that the STMD has significant effectiveness improvement over the TMD when the SE and/or damage are considered.

CFD three dimensional wake analysis in complex terrain

Even if wind energy technology is nowadays fully developed, the use of wind energy in very complex terrain is still challenging. In particular, it is challenging to characterize the combination effects of wind ow over complex terrain and wake interactions between nearby turbines and this has a practical relevance too, for the perspective of mitigating anomalous vibrations and loads as well improving the farm efficiency. In this work, a very complex terrain site has been analyzed through a Reynolds-averaged CFD (Computational Fluid Dynamics) numerical wind field model; in the simulation the inuence of wakes has been included through the Actuator Disk (AD) approach. In particular, the upstream turbine of a cluster of 4 wind turbines having 2.3 MW of rated power is studied. The objective of this study is investigating the full three-dimensional wind field and the impact of three-dimensionality on the evolution of the waked area between nearby turbines. A post-processing method of the output of the CFD simulation is developed and this allows to estimate the wake lateral deviation and the wake width. The reliability of the numerical approach is inspired by and crosschecked through the analysis of the operational SCADA (Supervisory Control and Data Acquisition) data of the cluster of interest.

Effects of thinning a forest stand on sub-canopy turbulence

The density of a forest canopy affects the degree of influence of vegetation on the mean and turbulence flow fields. Thinning a forest in situ is difficult and expensive therefore many studies investigating the effects of changing canopy density have been done in wind tunnels or with modeling. Here, we analyze data collected at 0.13h, 0.83h, and 1.13h (canopy height; h=21m) as the surrounding loblolly pine stand was progressively thinned three times. The first thinning removed the understory and the two subsequent thinnings removed whole trees leading to a 60% reduction in the overall stand density. As the forest was thinned, turbulence and wind speed near the surface (0.13h) increased and became more connected with above the canopy (1.13h). The variation of the three-dimensional wind components increased for 0.13h when the understory was thinned. Turbulence at 0.83h and 1.13h increased when whole trees were removed (2nd and 3rd thinning). An increase in the peak spectral power of the 0.13h vertical velocity indicated an increase in the influence of larger eddies surviving through the canopy, but these did not affect the vertical turbulence or momentum transfer.

A Three-Step Method for Estimating Vortex Center Locations in Four-Dimensional Space from Radar-Observed Tornadic Mesocyclones

AbstractThe recently developed two-dimensional variational methods for analyzing vortex winds from radar-observed mesocyclones can be extended to analyze three-dimensional vortex winds, but the first task for this extension is to estimate the vortex center location and its continuous variations in four-dimensional space so that the horizontal location of the vortex center can be expressed as a continuous function of height and time. To accomplish this task, a three-step method is developed in this paper. The method is applied to the Moore, Oklahoma, tornadic mesocyclone observed by the operational KTLX radar (Oklahoma City, Oklahoma) and the NSSL phased-array radar on 20 May 2013. The estimated vortex center trajectory at the ground level is verified with the tornado damage survey data. The estimated vortex center trajectories above the ground (up to 4-km height) reveal that the vortex core was initially tilted northeastward along the direction of the environmental flow and its vertical shear but became nearly vertical about 16 min later and 4 min before the vortex started to cause EF5 damages.

Utility of a three-dimensional wound measurement device in pressure ulcers

Utility of a three-dimensional wound measurement device in pressure ulcers Taichi Goto,1–3 Gojiro Nakagami,1,4 Ayano Nakai,1 Shuhei Noyori,1,5 Sanae Sasaki,6 Chieko Hayashi,6 Tomomitsu Miyagaki,7 Kaname Akamata,7 Hiromi Sanada1,4 1Department of Gerontological Nursing/Wound Care Management, Graduate School of Medicine, 2Global Leadership Initiative for an Age-Friendly Society, The University of Tokyo, Bunkyo-ku, 3Japan Society for the Promotion of Science, Chiyoda-ku, Japan; 4Global Nursing Research Center, Graduate School of Medicine, The University of Tokyo, 5Graduate Program for Social ICT Global Creative Leaders, The University of Tokyo, 6Department of Nursing, 7Department of Dermatology, The University of Tokyo Hospital, Bunkyo-ku, Tokyo, Japan Introduction: Depth assessment is important for severe pressure ulcers (PUs); however, a device for the metric measurement of wounds, including depth, is lacking in clinical settings. Recent technological advancements have enabled the evaluation of the depth of wounds, and three-dimensional measurements are now available. The aim of this study was to test the utility of a newly developed three-dimensional wound measurement device in the clinical setting.Methods: We recruited three patients, each with a PU, who were being treated by a PU team at a university hospital. We measured the length, width, area, and maximal depth of the ulcers by using the device and with the conventional method. The ulcer volume was measured only with the device. The difference in measurement results of the device before and after debridement was compared in the first patient. The difference in measurement results between the conventional method and the device was compared in the second patient. Correlation coefficients between the conventional method and the device obtained from longitudinal data were calculated in the third patient.Results: The changes in measurements between before and after debridement were easily detected by the device in the first patient. Although the maximal depth was different, the length, width, and area were consistent between the conventional method and the device in the second patient. The correlation coefficients of the length, width, and area between the conventional method and the device were 0.35, 0.48, and 0.59, respectively, in the third patient whose PU exhibited a vague wound edge.Conclusion: Although two-dimensional measurements were comparable between the conventional method and the device, there were some challenges to performing three-dimensional measurement more precisely. A further study is needed to determine the specific characteristics of wounds that result in poor measurement accuracy. Keywords: three-dimensional wound measurement device, wound depth, wound volume

Assimilation Impact of Different GPS Analysis Methods on Precipitation Forecast: A Heavy Rainfall Case Study of Kani City, Gifu Prefecture on July 15, 2010

In this study, we examined variations in predicted precipitable water produced from different Global Positioning System (GPS) zenith delay methods, and assessed the corresponding difference in predicted rainfall after assimilating the obtained precipitable water data. Precipitable water data estimated from the GPS and three-dimensional horizontal wind velocity field derived from the X-band dual polarimetric radar were assimilated in CReSS and rainfall forecast experiments were conducted for the heavy rainfall system in Kani City, Gifu Prefecture on July 15, 2010. In the GPS analysis, a method to simultaneously estimate coordinates and zenith delay, i.e., the simultaneous estimation method, and a method to successively estimate coordinates and zenith delay, i.e., the successive estimation method, were used to estimate precipitable water. The differences generated from using predicted orbit data provided in pseudo-real time from the International GNSS (Global Navigation Satellite System) Service for geodynamics (IGS) versus precise orbit data released after a 10-day delay were examined. The change in precipitable water due to varying the analysis methods was larger than that due to the type of satellite orbit information. In the rainfall forecast experiments, those using the successive estimation method results had a better precision than those using the simultaneous estimation method results. Both methods that included data assimilation had higher rainfall forecast precisions than the forecast precision without precipitable water assimilation. Water vapor obtained from GPS analysis is accepted as important in rainfall forecasting, but the present study showed additional improvements can be attained from incorporating a zenith delay analysis method.

Novel techniques in wind engineering

While the Alan Davenport Wind Engineering Chain is still valid today, the wind engineering techniques and methodologies have evolved. These changes relate to methods of collecting full scale data, physical and numerical modeling techniques, analysis techniques and wind-structure interaction approaches. These methodologies allow us to look at a more diverse spectrum of wind events including non-stationary, non-synoptic winds and their impact on buildings and structures. Spatially distributed full scale data combined with mesoscale and microscale simulations are more fitted today to characterize the local climatic scales associated to these complex wind events. These wind fields are three-dimensional, non-stationary and sometimes non-Gaussian in nature. However, our well-established Boundary Layer Wind Tunnels produce straight and steady wind and are limited in Reynolds number.The development of larger, multi-fan and sometimes three-dimensional wind facilities has now enabled more realistic laboratory simulations of surface flows for these events. Also, it invites new insight in data analysis and the way we treat the wind-structure interaction problems in a non-stationary context.In view of all this, we provide a review of new emerging technologies and examples of their applicability in the context of new experiments conducted at the WindEEE Research Institute at Western.

Characterizing Cell Migration Within Three-dimensional <em>In Vitro</em> Wound Environments

Currently, most in vitro models of wound healing, such as well-established scratch assays, involve studying cell migration and wound closure on two-dimensional surfaces. However, the physiological environment in which in vivo wound healing takes place is three-dimensional rather than two-dimensional. It is becoming increasingly clear that cell behavior differs greatly in two-dimensional vs. three-dimensional environments; therefore, there is a need for more physiologically relevant in vitro models for studying cell migration behaviors in wound closure. The method described herein allows for the study of cell migration in a three-dimensional model that better reflects physiological conditions than previously established two-dimensional scratch assays. The purpose of this model is to evaluate cell outgrowth via the examination of cell migration away from a spheroid body embedded within a fibrin matrix in the presence of pro- or anti-migratory factors. Using this method, cell outgrowth from the spheroid body in a three-dimensional matrix can be observed and is easily quantifiable over time via brightfield microscopy and analysis of spheroid body area. The effect of pro-migratory and/or inhibitory factors on cell migration can also be evaluated in this system. This method provides researchers with a simple method of analyzing cell migration in three-dimensional wound associated matrices in vitro, thus increasing the relevance of in vitro cell studies prior to the use of in vivo animal models.