Download or read book Numerical Simulation of Local Climatic Impact of an Operating Wind Turbine written by Yuan Yang and published by Open Dissertation Press. This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Numerical Simulation of Local Climatic Impact of an Operating Wind Turbine" by Yuan, Yang, 杨源, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Wind energy is commonly considered to be a clean and environmentally friendly renewable energy resource, as they do not pollute our atmosphere with greenhouse gas, nor do they cause any radioactive problems compared to nuclear energy. However, there are still some environmental impacts due to the installation and operation of the wind turbines that cannot be ignored, such as noise, visual and climatic impact. Especially, the observed local climate change in some wind farm areas has attracted general concern in recent years. Experts suspected that long time operation of wind turbines in an area can cause changes to local precipitation, evaporation of the water on earth surface, and even affect the frequency of drought happening. Nevertheless, we still cannot figure out whether these changes would be caused by wind turbines or not. The target of this study is to investigate the potential local impact of an operating wind turbine by numerical simulation. Because of the big geometric size of commercial wind turbines, experimental method is very limited in this type of study. Numerical simulation using CFD is considered to be a suitable approach and commercial software "FLUENT" is utilized in this study. Firstly, an accurate 3-D numerical wind turbine model was established and the frozen blade method was used to realize the rotation of the wind blades. Before further simulation, a wind-tunnel test has been undertaken by using a scaled physical wind turbine model for validation purpose. The experimental results show good agreement with those predicted by the numerical simulation. This suggested that the computation results were validated and the computational model can be used for further study. In this research, three wind turbine cases, with different typical ambient temperature and surface temperature, were simulated. Characters like wake structure, turbulence intensity and local temperature change was collected and analyzed in each simulated case. The results show that the operating wind turbine can bring obvious velocity deficit in the wake and a strong turbulence intensity enhancement was observed at the top tip because of the rotation. Also, local temperature change was found in the near wake region. The investigation of the local impact of the operating wind turbine is very significant. This study provides a valuable insight into the potential impacts of wind farms on local meteorology, which is rarely studied before. Meanwhile, a more comprehensive study on the effect of a wind farm on the environment is highly recommended. DOI: 10.5353/th_b5016282 Subjects: Wind turbines - Environmental aspects

Download or read book Numerical Simulation of Local Climatic Impact of an Operating Wind Turbine written by Yuan Yang (M. Phil.) and published by . This book was released on 2012 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation of Local Climatic Impact of an Operating Wind Turbine written by 杨源 and published by . This book was released on 2012 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulations of the Impact of Large Wind Farms on Local Climate written by Yogesh Rao Kadiyala and published by . This book was released on 2015 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to decrease in fossil fuel levels, the world is shifting focus towards renewable sources of energy. With an annual average growth rate of 25%, wind is one of the foremost source of harnessing cleaner energy for production of electricity. Wind turbines have been developed to tap power from wind. As a single wind turbine is insufficient, multiple turbines are installed forming a wind farm. Generally, wind farms can have hundreds to thousands of turbines concentrated in a small region. There have been multiple studies centering the influence of weather on such wind farms, but no substantial research focused on how wind farms effect local climate. Technological advances have allowed development of commercial wind turbines with a power output greater than 7.58 MW. This has led to a reduction in required number of turbines and has optimized land usage. Hence, current research considers higher power density compared to previous works that relied on wind farm density of 2 to 4 W/m 2 . Simulations were performed using Weather Research and Forecasting software provided by NCAR. The region of simulation is Southern Oregon, with domains including both onshore and offshore wind farms. Unlike most previous works, where wind farms were considered to be on a flat ground, effects of topography have also been considered here. Study of seasonal effects over wind farms has provided better insight into changes in local wind direction. Analysis of mean velocity difference across wind farms at a height of 10m and 150m gives an understanding of wind velocity profiles. Results presented in this research tends to contradict earlier belief that velocity reduces throughout the farm. Large scale simulations have shown that sometimes, more than 50% of the farm can have an increased wind velocity of up to 1m/sat an altitude of 10m.

Download or read book Numerical Simulation of Canopy Flows written by Günter Groß and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 243 pages. Available in PDF, EPUB and Kindle. Book excerpt: Starting with the description of meteorological variables in forest canopies and its parameter variations, a numerical three-dimentional model is developed. Its applicability is demonstrated, first, by wind sheltering effects of hedges and, second, by the effects of deforestation on local climate in complex terrain. Scientists in ecology, agricultural botany and meteorology, but also urban and regional lanners will profit from this study finding the most effective solution for their specific problems.

Download or read book Simulation of the Atmospheric Boundary Layer for Wind Energy Applications written by Nikola Marjanovic and published by . This book was released on 2015 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Energy production from wind is an increasingly important component of overall global power generation, and will likely continue to gain an even greater share of electricity production as world governments attempt to mitigate climate change and wind energy production costs decrease. Wind energy generation depends on wind speed, which is greatly influenced by local and synoptic environmental forcings. Synoptic forcing, such as a cold frontal passage, exists on a large spatial scale while local forcing manifests itself on a much smaller scale and could result from topographic effects or land-surface heat fluxes. Synoptic forcing, if strong enough, may suppress the effects of generally weaker local forcing. At the even smaller scale of a wind farm, upstream turbines generate wakes that decrease the wind speed and increase the atmospheric turbulence at the downwind turbines, thereby reducing power production and increasing fatigue loading that may damage turbine components, respectively. Simulation of atmospheric processes that span a considerable range of spatial and temporal scales is essential to improve wind energy forecasting, wind turbine siting, turbine maintenance scheduling, and wind turbine design. Mesoscale atmospheric models predict atmospheric conditions using observed data, for a wide range of meteorological applications across scales from thousands of kilometers to hundreds of meters. Mesoscale models include parameterizations for the major atmospheric physical processes that modulate wind speed and turbulence dynamics, such as cloud evolution and surface-atmosphere interactions. The Weather Research and Forecasting (WRF) model is used in this dissertation to investigate the effects of model parameters on wind energy forecasting. WRF is used for case study simulations at two West Coast North American wind farms, one with simple and one with complex terrain, during both synoptically and locally-driven weather events. The model's performance with different grid nesting configurations, turbulence closures, and grid resolutions is evaluated by comparison to observation data. Improvement to simulation results from the use of more computationally expensive high resolution simulations is only found for the complex terrain simulation during the locally-driven event. Physical parameters, such as soil moisture, have a large effect on locally-forced events, and prognostic turbulence kinetic energy (TKE) schemes are found to perform better than non-local eddy viscosity turbulence closure schemes. Mesoscale models, however, do not resolve turbulence directly, which is important at finer grid resolutions capable of resolving wind turbine components and their interactions with atmospheric turbulence. Large-eddy simulation (LES) is a numerical approach that resolves the largest scales of turbulence directly by separating large-scale, energetically important eddies from smaller scales with the application of a spatial filter. LES allows higher fidelity representation of the wind speed and turbulence intensity at the scale of a wind turbine which parameterizations have difficulty representing. Use of high-resolution LES enables the implementation of more sophisticated wind turbine parameterizations to create a robust model for wind energy applications using grid spacing small enough to resolve individual elements of a turbine such as its rotor blades or rotation area. Generalized actuator disk (GAD) and line (GAL) parameterizations are integrated into WRF to complement its real-world weather modeling capabilities and better represent wind turbine airflow interactions, including wake effects. The GAD parameterization represents the wind turbine as a two-dimensional disk resulting from the rotation of the turbine blades. Forces on the atmosphere are computed along each blade and distributed over rotating, annular rings intersecting the disk. While typical LES resolution (10-20 m) is normally sufficient to resolve the GAD, the GAL parameterization requires significantly higher resolution (1-3 m) as it does not distribute the forces from the blades over annular elements, but applies them along lines representing individual blades. In this dissertation, the GAL is implemented into WRF and evaluated against the GAD parameterization from two field campaigns that measured the inflow and near-wake regions of a single turbine. The data-sets are chosen to allow validation under the weakly convective and weakly stable conditions characterizing most turbine operations. The parameterizations are evaluated with respect to their ability to represent wake wind speed, variance, and vorticity by comparing fine-resolution GAD and GAL simulations along with coarse-resolution GAD simulations. Coarse-resolution GAD simulations produce aggregated wake characteristics similar to both GAD and GAL simulations (saving on computational cost), while the GAL parameterization enables resolution of near wake physics (such as vorticity shedding and wake expansion) for high fidelity applications. For the first time, to our knowledge, this dissertation combines the capabilities of a mesoscale weather prediction model, LES, and high-resolution wind turbine parameterizations into one model capable of simulating a real array of wind turbines at a wind farm. WRF is used due to its sophisticated environmental physics models, frequent use in the atmospheric modeling community, and grid nesting with LES capabilities. Grid nesting is feeding lateral boundary condition data from a coarse resolution simulation to a finer resolution simulation contained within the coarse resolution simulation's domain. WRF allows the development of a grid nesting strategy from synoptic-scale to microscale LES relevant for wind farm simulations; this is done by building on the results from the investigation of model parameters for wind energy forecasting and the implementation of the GAD and GAL wind turbine parameterizations. The nesting strategy is coupled with a GAD parameterization to model the effects of wind turbine wakes on downstream turbines at a utility-scale Oklahoma wind farm. Simulation results are compared to dual-Doppler measurements that provide three-dimensional fields of horizontal wind speed and direction. The nesting strategy is able to produce realistic turbine wake effects, while differences with the measurements can mostly be attributed to the quality of the available weather input data.

Download or read book Wind Vision written by U. S. Department U.S. Department of Energy and published by CreateSpace. This book was released on 2015-03-18 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a detailed roadmap of technical, economic, and institutional actions by the wind industry, the wind research community, and others to optimize wind's potential contribution to a cleaner, more reliable, low-carbon, domestic energy generation portfolio, utilizing U.S. manu-facturing and a U.S. workforce. The roadmap is intended to be the beginning of an evolving, collaborative, and necessarily dynamic process. It thus suggests an approach of continual updates at least every two years, informed by its analysis activities. Roadmap actions are identified in nine topical areas, introduced below.

Download or read book The Hybrid Wind Farm Parameterization written by Yang Pan and published by . This book was released on 2018 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goals of this research are to improve the current treatment of wind farms in large-scale models via a new hybrid wind farm parameterization to better understand the potential impacts of offshore wind farms on the environment. ☐ Wind turbines extract energy from the atmosphere and the resulting wakes affect the boundary layer and the environment. The approach chosen in this dissertation to study these impacts of wind turbines is numerical simulations utilizing the weather prediction model called Weather Research and Forecast (WRF), in which wind farms are currently parameterized as simple elevated sinks of kinetic energy and sources of turbulent kinetic energy (TKE). A well-developed wind farm parameterization is essential to better understand the potential impacts of wind farms on weather and climate at the regional to global scales. ☐ The first part of this dissertation is therefore a case study to understand the impacts of hypothetical, large, offshore wind farms on local meteorology, especially the precipitation, employing the current two most widely used wind farm parameterizations. This study quantitatively tests whether the offshore turbines may affect precipitation patterns during Hurricane Harvey, since Hurricane Harvey brought to the Texas coast possibly the heaviest rain ever recorded in U.S. history, which then caused flooding at unprecedented levels. Model results indicate that the offshore wind farms have a strong impact on the distribution of accumulated precipitation, with an obvious decrease onshore, downstream of the wind farms, and an increase in the offshore areas, upstream of or within the wind farms. The accumulated precipitation during Harvey was reduced by up to 21% in the presence of offshore wind farms consisting of hundreds of thousands of turbines. Compared with the control case with no wind turbines, increased horizontal wind divergence and lower vertical velocity are found where the precipitation is reduced onshore, whereas increased horizontal wind convergence and higher vertical velocity occur upstream or within the offshore wind farms. The sensitivity to the size of the offshore array, the inter-turbine spacing, and the details of the wind-farm parameterization is assessed. ☐ In the second part of this dissertation, a new hybrid wind farm parameterization (a.k.a. hybrid model) is developed, which is not based on physical processes or conservation laws, but on a multiple linear regression of the results of sophisticated, high-resolution large-eddy simulations (LES) with simple geometric properties of the wind farm layout. The need for the new hybrid model arises from three previously-unknown weaknesses in the current wind farm parameterization in WRF, i.e., it neglects the effects of wind direction, it is insensitive to the relative position of the wind turbines within the farm, and it injects excessive TKE in the atmosphere. The new hybrid parameterization, however, successfully remedies these weaknesses. After validations against observations collected at an existing offshore wind farm (Lillgrund in Sweden) and against LES results at three hypothetical wind farms, the wind speed deficit and TKE predicted with the hybrid model are found to be in excellent agreement with the LES results and the wind power production estimated with the hybrid model also performs well compared with the observation data. In conclusion, wind turbine position, wind direction, and added TKE are essential to properly model wind farm effects on the surroundings and the hybrid wind farm parameterization is a promising tool to incorporate them in meso- and large-scale simulations.

Download or read book Wind Turbines in Cold Climates written by Lorenzo Battisti and published by Springer. This book was released on 2016-10-09 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the key concerns regarding the operation of wind turbines in cold climates and focuses in particular on the analysis of icing and methods for its mitigation. Topics covered include the implications of cold climates for wind turbine design and operation, the relevance of icing for wind turbines, the icing process itself, ice prevention systems and thermal anti-icing system design. In each chapter, care is taken to build systematically on the basic knowledge, providing the reader with the level of detail required for a thorough understanding. An important feature is the inclusion of several original analytical and numerical models for ready computation of icing impacts and design assessment. The breadth of the coverage and the in-depth scientific analysis, with calculations and worked examples relating to both fluid dynamics and thermodynamics, ensure that the book will serve not only as a textbook but also as a practical manual for general design tasks.

Download or read book Numerical Computation of Wind Turbine Flows and Fluid Problem by OpenFOAM and ANSYS written by Yi-Ching Wang and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind energy is the mainstream source of clean and renewable energy and it is also the fastest-growing source of sustainable energy in the world. In the Global Wind Energy Council's report in 2014, wind industry grew 44% worldwide. In order to optimize the efficiency of wind farms, it is important to observe wake interactions among wind turbines. Computational mathematics and mechanics provide fundamental methods and tools for simulating physical processes. Numerical computation can offer important insights and data that are either difficult or expensive to measure or to perform tests experimentally. In this dissertation, we use Computational Fluid Dynamics (CFD) software OpenFOAM and ANSYS FLUENT to simulate the wake effect of Horizontal Axis Wind Turbines (HAWT) and related problems. Numerical simulation can also help us comprehend and control man-made disasters. Air craft crashworthiness and human survivability are of utmost concerns in any emergency landing situation. Motivated by the air incidents lately, the disappearance of Malaysia Airlines Flight MH370 in March 2014 and Germanwings Flight 9525 crash in March 2015, we use Computational Structural Dynamics (CSD) software ANSYS Explicit Dynamics and LS-DYNA to try different numerical simulations of Airbus A320 crashing into a wall and compare the results to the reality. We calculate three CFD problems in this dissertation: lid-driven problems, one turbine wake problem, and two serial turbines wake problem. We simulate a lid-driven flow in both two- (2D) and three-dimension (3D) to compare the simulation capability of the three turbulence modelings, i.e., Direct Numerical Simulation (DNS), Large Eddy Simulation (LES), and Reynolds-Averaged Navier-Stokes Equations Simulation (RANS) by OpenFOAM. Among these three turbulence models, we can find that LES is capable of capturing more details of turbulence flow. We simulate the airflow effect of one wind turbine with both fixed angular velocity and wind-driven case, run benchmark tests based on NRELs reports, and compare the numerical results under the same condition by OpenFOAM and FLUENT. For the fixed angular velocity case, we use wind speed 8 m/s and angular velocity of the wind turbine 75 deg/s. For the wind-driven case, we use wind speed 8 m/s and 16 m/s and the angular velocity of the wind turbine calculated by FLUENT converges faster than OpenFOAM case. We simulate the interactions of wake flow for two serial wind turbines by FLUENT. We use wind speed 8 m/s and angular velocity of the wind turbine 75 deg/s. The wake of former turbine affects the rear one and the diffusion of flow caused by two turbines can be seen clearly. For both one and two serial turbines problems, the turbulence model RANS [lowercase kappa][lowercase epsilon] is used. We calculate and simulate Airbus A320 crashing into a wall by ANSYS Explicit Dynamics and LS-DYNA. For ANSYS Explicit Dynamics, we use the angle of approach 0°, 15°, and 30°. For LS-DYNA, we only test the pitch angles 0°. For all cases, we use the speed of aircarft 200 m/s. The deformation of both aircraft and wall can be seen clearly. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/155665

Download or read book Modeling Simulation and Optimization of Wind Farms and Hybrid Systems written by Karam Maalawi and published by BoD – Books on Demand. This book was released on 2020-03-25 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: The reduction of greenhouse gas emissions is a major governmental goal worldwide. The main target, hopefully by 2050, is to move away from fossil fuels in the electricity sector and then switch to clean power to fuel transportation, buildings and industry. This book discusses important issues in the expanding field of wind farm modeling and simulation as well as the optimization of hybrid and micro-grid systems. Section I deals with modeling and simulation of wind farms for efficient, reliable and cost-effective optimal solutions. Section II tackles the optimization of hybrid wind/PV and renewable energy-based smart micro-grid systems.

Download or read book Automated Surface Observing System written by and published by . This book was released on 1998 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Wind Energy Modeling and Simulation written by Paul Veers and published by Energy Engineering. This book was released on 2020-01-02 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind Energy Modeling and Simulation: Atmosphere and plant is the first book in a comprehensive two-volume set on wind farm power modelling; the key to efficient wind plant design and wind power growth.

Download or read book Numerical Simulation of Environmental Flow Over Urban Landscape for Applications to Renewable Energy written by Xiaoyan Ying and published by . This book was released on 2015 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: Development of renewable energy solutions has become a major interest among environmental organizations and governments around the world due to an increase in energy consumption and global warming. One fast growing renewable energy solution is the application of wind energy in cities. To qualitative and quantitative predict wind turbine performance in urban areas, CFD simulation is performed on real-life urban geometry and wind velocity profiles are evaluated. Two geometries in Arizona is selected in this thesis to demonstrate the influence of building heights; one of the simulation models, ASU campus, is relatively low rise and without significant tall buildings; the other model, the downtown phoenix model, are high-rise and with greater building height difference. The content of this thesis focuses on using RANS computational fluid dynamics approach to simulate wind acceleration phenomenon in two complex geometries, ASU campus and Phoenix downtown model. Additionally, acceleration ratio and locations are predicted, the results are then used to calculate the best location for small wind turbine installments.

Download or read book Wind Energy Exploitation in Urban Environment written by Lorenzo Battisti and published by Springer. This book was released on 2018-03-09 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents numerical and experimental research in the field of wind energy exploitation in urban environments. It comprises a selection of the best papers from the international colloquium “Research and Innovation on Wind Energy Exploitation in Urban Environment” (TUrbWind), held in Riva del Garda, Italy in June 2017. The book includes contributions from different research fields in urban wind resources, wind energy conversion systems, and urban integration, mainly focusing on the following topics: · concepts for urban and open landscape micro wind turbines, · integration of micro wind turbines in existing structures, · built-environment and high-turbulence sites’ impacts on urban wind turbines, · measuring and modeling wind resource in built environments, · rotor performance and wake features of micro wind turbines. It is a valuable resource for researchers and practitioners interested in the integration of wind energy systems and turbines in urban areas.

Download or read book Wind Farm Modeling written by Christian Santoni-Ortiz and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation is focused on numerical modeling of wind turbines. An initial set of simulations is performed to assess the effect of the tower and nacelle on the wake of a wind turbine. The wind turbine is modeled using the Actuator Line Model for the rotor and the Immersed Boundary Method for the tower and nacelle. Results are compared with the experimental measurements made at NTNU (Norwegian University of Science and Technology), and numerical simulations available in the literature. For the first time, we show that the tower and nacelle not only produce a velocity deficit in the wake but also affect the entrainment of mean kinetic energy. The wake of the tower interacts with that generated by the turbine blades, promoting the breakdown of the tip vortex and increasing the mean kinetic energy flux into the wake. Additionally, we studied the effect of topography on the performance and wake of a wind turbine. The topography consists of wavy ridges that are perpendicular to the flow direction. The effect of the relative position of the rotor and terrain geometry is assessed by placing the turbine either at the crest or trough of the undulating wall. To study wind turbines under realistic conditions, one-way nested mesoscale to microscale simulations of an on-shore wind farm have been performed using the Weather Research and Forecasting (WRF) model. Each simulation contains five nested domains modeling the mesoscale wind field using the planetary boundary layer scheme on the entire north Texas Panhandle region to microscale wind fluctuations and turbine wakes of a wind farm with Large-Eddy simulation (LES). Moreover, an additional nesting with our in-house LES code is performed. Numerical results agree well with meteorological, LiDAR and SCADA data. Power production and momentum deficit obtained with our in-house LES code and actuator disk model presented a better agreement than WRF because the simulation captures the wind shear on the rotor.