Wind energy is gaining critical ground in the area of renewable energy, with wind energy being predicted to provide up to 8% of the worlds consumption of electricity by 2021. This book reviews the ...design and functionality of wind turbine rotor blades as well as the requirements and challenges for composite materials used in both current and future designs of wind turbine blades. Part one outlines the challenges and developments in wind turbine blade design, including aerodynamic and aeroelastic design features, fatigue loads on wind turbine blades, and characteristics of wind turbine blade airfoils. Part two discusses the fatigue behavior of composite wind turbine blades, including the micromechanical modelling and fatigue life prediction of wind turbine blade composite materials, and the effects of resin and reinforcement variations on the fatigue resistance of wind turbine blades. The final part of the book describes advances in wind turbine blade materials, development and testing, including biobased composites, surface protection and coatings, structural performance testing and the design, manufacture and testing of small wind turbine blades This book offers a comprehensive review of the recent advances and challenges encountered in wind turbine blade materials and design, and will provide an invaluable reference for researchers and innovators in the field of wind energy production, including materials scientists and engineers, wind turbine blade manufacturers and maintenance technicians, scientists, researchers and academics.
A systematic review and analysis of the literature of diffuser-augmented horizontal-axis turbines are presented. A collection of 155 articles in the area is analyzed and classified. The work sample ...is divided into 16 main research branches for discussion. Performance assessment metrics are proposed based on power coefficient and tip-speed-ratio, to quantify and compare all diffuser-augmented turbines in a unified, meaningful manner. Design suggestions for the development of diffuser-augmented turbines are pointed out based on the analysis of 73 cases. A power coefficient assessment on the work sample presented that, in 58% of the cases, the diffuser-augmented turbines surpassed the power coefficient of scaled bare turbines of the same diameter. A tip-speed-ratio assessment presented that almost 90% of the diffuser-augmented turbines developed a narrower operational interval. Five high-performing diffuser-augmented turbines are discussed, highlighting their methodologies and contributions. Caution is advised when coupling a diffuser to a bare turbine with an already high power coefficient; the diffuser-augmented turbine, especially in those cases, should be designed employing a simultaneous diffuser-rotor optimization.
•Systematic analysis of the current literature on diffuser-augmented horizontal-axis turbines is made.•A collection of 155 articles is dived in 16 research branches and discussed.•A diffuser-enhancement parameter is defined and used to compare the effectiveness of diffusers.•In 58% of the DAHT analyzed, the diffuser increases the Cp when compared to a bare turbine scaled to the diffuser diameter.•Diffuser-augmented horizontal turbines tend to display narrower Cp versus TSR curves compared to its bare version.
Today, nanoparticles are used as additives because of their unique properties. The aim of the present research is to investigate the effect of the addition of TiO.sub.2 nanoparticles to pure oil on ...properties such as viscosity, viscosity index, flash point, density, friction coefficient and frictional force in the pin-on-disk system. For this purpose, the nanofluids were synthesized using turbine meter oil as a base oil and TiO.sub.2 additive with 0.05, 0.1, 0.2, 0.3, 0.4 and 1 mass% and oleic acid surfactants, followed by testing the mentioned properties. The results show that the kinematic viscosity of the oil is increased with increasing nanoparticles and reducing the temperature. Viscosity index and flash point temperature in 0.4 mass% were increased by 6.65% and 1.77%, respectively. The pour point temperature in 0.05-0.2 mass% was increased by 3%. A pin-on-disk system was used to measure the friction coefficient and the frictional force between the pin and disk in the presence of pure oil and nanofluids after 2 h of abrasion. The results showed that friction coefficient and frictional force were, respectively, decreased by 37.1% and 37.1% by adding 0.1 mass% of TiO.sub.2. The depth of the abrasive pins for 4 h was measured by the SEM analysis. The addition of TiO.sub.2 nanoparticles showed the lowest abrasion and the most improvement were related to 0.1 mass% TiO.sub.2 nanoparticles with a wear depth of 38.46 mum. Compared with turbine meter oil, it shows a 71.43% improvement.
Actuator nonidealities, such as backlash, dead zone, and others, present in a number of industrial systems, are known to severely degrade system performance. Providing nonconservative closed-loop ...robust performance guarantees for these systems in a consistent manner has been an open problem. For example, in boiler/turbine units, the turbine valve position actuation for manipulating steam flow rate is characterized by a small mismatch between the turbine valve command and the actual valve position, producing a small steady-state regulation error in the plant outputs. The standard linear Formula Omitted controller designed to provide zero steady-state error regulation drives this error to zero, producing the undesirable oscillations in the control signals and the plant outputs. This paper develops a nonsmooth Formula Omitted output regulator theory addressing this problem and applies this theory to the experimentally validated boiler/turbine model with actuator dead zone. The simulation results showing a considerable performance improvement are given.
Written by one of the field’s most well known experts, this book has long been the standard for engineers involved in the design, selection, maintenance and operation of gas turbines. With far ...reaching, comprehensive coverage across a range of topics from design specifications to maintenance troubleshooting, this one-stop resource provides newcomers to the industry with all the essentials to learn and fill knowledge gaps, and established practicing gas turbine engineers with a reliable go-to reference. This new edition is up to date with new legislation and emerging topics to help the next generation of gas turbine professionals understand the underlying principles of gas turbine operation, the economic considerations and implications of operating these machines, and how they fit in with alternative methods of power generation.
To enable the fast growth of the floating offshore wind industry, simulation models must be validated with experimental data. Floating wind model-scale experiments in wind–wave facilities have been ...performed over the last two decades with varying levels of fidelity and limitations. However, the turbine controls in these experiments have considered only limited control strategies and implementations. To allow for control co-design, this research focuses on implementing and experimentally validating more advanced turbine control actions and strategies in a wind–wave basin for a 1:70-scale model of the International Energy Agency’s wind 15 MW reference wind turbine. The control strategies analyzed include torque control, collective pitch control, and transition region control (setpoint smoothing). Our experimental and numerical results include the effects of varying rotor speeds, blade pitches, and wind environments on the turbine thrust and torque. Numerical models from three different software tools are presented and compared to the experimental results. Their ability to effectively represent the aero-dynamic response of the wind turbine to the control actions is successfully validated. Finally, turbine controller tuning parameters based on the derivatives of thrust and torque are derived to allow for improved offshore wind turbine dynamics and to validate the ability of modeling tools to model the dynamics of floating offshore wind turbines with control co-design.
Wind-Turbine and Wind-Farm Flows: A Review Porté-Agel, Fernando; Bastankhah, Majid; Shamsoddin, Sina
Boundary-layer meteorology,
01/2020, Letnik:
174, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Wind energy, together with other renewable energy sources, are expected to grow substantially in the coming decades and play a key role in mitigating climate change and achieving energy ...sustainability. One of the main challenges in optimizing the design, operation, control, and grid integration of wind farms is the prediction of their performance, owing to the complex multiscale two-way interactions between wind farms and the turbulent atmospheric boundary layer (ABL). From a fluid mechanical perspective, these interactions are complicated by the high Reynolds number of the ABL flow, its inherent unsteadiness due to the diurnal cycle and synoptic-forcing variability, the ubiquitous nature of thermal effects, and the heterogeneity of the terrain. Particularly important is the effect of ABL turbulence on wind-turbine wake flows and their superposition, as they are responsible for considerable turbine power losses and fatigue loads in wind farms. These flow interactions affect, in turn, the structure of the ABL and the turbulent fluxes of momentum and scalars. This review summarizes recent experimental, computational, and theoretical research efforts that have contributed to improving our understanding and ability to predict the interactions of ABL flow with wind turbines and wind farms.
Combined cycles have integration of different cycles for the effective utilization of heat energy. Among different measures the intercooling and reheating are the commonly used techniques for ...improving the performance of thermal power cycles. Here, the study of combined cycle configurations having gas turbine, steam turbine and ammonia-water turbine with intercooling and reheating has been undertaken. The present paper analyzes the different configurations of intercooled reheat gas turbine cycle based combined cycle configurations using steam and/or ammonia-water mixture as coolant to gas turbine blades for fixed design condition - turbine inlet temperature of 2000K, cycle pressure ratio 40 and ambient condition of 303K. The comparison of different configurations shows that the work output of 1789.39 kJ/kg of air is obtained. First law and second law efficiencies of 62.50% and 60.7% is maximum for triple pressure heat recovery generator having ammonia-water turbine at each pressure level. The cost of electricity production is minimum for maximum work output and corresponds to 0.06727USD/kWh.
•Thermo-economic analysis for different configurations of intercooled reheat gas turbine cycle based combined cycle.•Effect of separator temperature, steam bleeding on thermo-economic performance is studied.•Study of combined cycle using different cooling means in gas turbine.
Vertical-axis wind turbines (VAWTs) are being reconsidered as a complementary technology to the more widely used horizontal-axis wind turbines (HAWTs) due to their unique suitability for offshore ...deployments. In addition, field experiments have confirmed that vertical-axis wind turbines can interact synergistically to enhance the total power production when placed in close proximity. Here, we use an actuator line model in a large-eddy simulation to test novel VAWT farm configurations that exploit these synergistic interactions. We first design clusters with three turbines each that preserve the omni-directionality of vertical-axis wind turbines, and optimize the distance between the clustered turbines. We then configure farms based on clusters, rather than individual turbines. The simulations confirm that vertical-axis wind turbines have a positive influence on each other when packed in well-designed clusters: such configurations increase the power generation of a single turbine by about 10 percent. In addition, the cluster designs allow for closer turbine spacing resulting in about three times the number of turbines for a given land area compared to conventional configurations. Therefore, both the turbine and wind-farm efficiencies are improved, leading to a significant increase in the density of power production per unit land area.
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