Numerical simulations of wind turbine wake interactions using actuator line and les models

Download
2019
Önel, Hüseyin Can
Wind is one of the most promising renewable energy resources of the future. After years of optimization studies, Horizontal Axis Wind Turbines shine out as the most efficient type and have been the only model used in large scale commercial wind farms. Layout planning plays an important role in getting the most power out of a wind farm as much as turbine blade design. Most important parameter in this planning phase is the inevitable wake generated by rotors and its impact on other wind turbines which results in power loss. Wake is a higly complex structure whose effects are immensely sensitive to boundary conditions. This situation raises a problem that is difficult to model, especially in wind farms where dozens of turbines are in operation simultaneously. Various analytical and empirical data based simplified wake models have been developed, but they all have a limited use in practical applications. With rapid advancements in computer technologies, Computational Fluid Dynamics offers high fidelity methods for wind turbine and wake simulations. One of these methods is the Actuator Line Model, where turbine blades are represented as distributed volumetric forces without the need of boundary layer resolution, hence saving some significant computational resource. In this study, accuracy and feasibility of Actuator Line Model in wind energy applications is evaluated. Model's sensitivity to several simulation parameters are assessed and two in-line turbines are simulated using best performing values. OpenFOAM software is used for Actuator Line Model implementation and Navier-Stokes solutions. Results are validated with Blade Element Momentum theory solutions and the model performed well in estimating turbine power production. Turbulent and vortical structures in the wake are best captured with LES turbulence model, velocity deficit curves and field variable plots are presented. Also, the model is capable of handling non-homogeneous conditions under atmospheric boundary layer flow.

Suggestions

Design of a modular, axial-flux direct drive permanent magnet generator for wind turbines
Başkaya, Aydın; Keysan, Ozan; Department of Electrical and Electronics Engineering (2018)
Wind energy technology is becoming more important issue in terms of renewable energy applications. Theoretical maximum of wind energy utilization is known (which is predetermined by Betz as 59%) and generally imperfections in blade manufacture reduce the actual energy yield of the turbine less than the useable energy. Therefore, maximum energy yield from generator topology is desired. According to fault statistics of wind turbines, most of the cases are related to gearbox failures. Mechanical losses and hea...
Modeling and investigation of fault ride through capability of variable speed wind turbines
Koç, Erkan; Güven, Ali Nezih; Department of Electrical and Electronics Engineering (2010)
Technological improvements on wind energy systems with governmental supports have increased the penetration level of wind power into the grid in recent years. The high level of penetration forces the wind turbines stay connected to the grid during the disturbances in order to enhance system stability. Moreover, power system operators must revise their grid codes in parallel with these developments. This work is devoted to the modeling of variable speed wind turbines and the investigation of fault ride troug...
Development of a high-order navier-stokes solver for aeroacoustic predictions of wind turbine blade sections
Yalçın, Özgür; Özyörük, Yusuf; Department of Aerospace Engineering (2015)
Increased interest in renewable energy in the world has lead to research on wind turbines at a great pace. However, these turbines have come with a noise problem. The noise source of wind turbines is primarily aerodynamic noise highly related to complex, three dimensional, unsteady flow fields around them. Therefore, determination of these sources requires successful, accurate, turbulent flow solutions. In addition, because acoustic waves are non-dispersive and non-dissipative, such solutions must be carrie...
Ice accretion prediction on wind turbine blades and aerodynamic shape optimization for minimizing power production losses
Yırtıcı, Özcan; Tuncer, İsmail Hakkı; Özgen, Serkan; Department of Aerospace Engineering (2018)
The global wind energy resources are plentiful in cold climate regions and mountainous areas, which cause ice formation on wind turbine blades. Prediction of ice accretion on wind turbine blades makes it possible to estimate the power losses due to icing. Ice accretion on wind turbine blades is responsible for significant increases in aerodynamic drag and decreases in aerodynamic lift, and may even cause premature flow separation. All these events create power losses and the amount of power loss depends on ...
Simultaneous optimization of electrical interconnection configuration and cable sizing in offshore wind farms
Fahrioğlu, Murat; Sedighi, Mohsen; Moradzadeh, Mohammad; Kukrer, Osman (Springer Science and Business Media LLC, 2018-1-18)
Offshore wind farm (OWF) is the largest renewable energy resource. The electrical interconnection cost of OWFs is a considerable fraction of the overall design cost of the farm. In order to minimize the investment and operational costs, this paper proposes an optimization formulation to find the optimal electrical interconnection configuration of wind turbines (WTs), and the optimal cable sizing simultaneously. This simultaneous minimization of total trenching length and cable dimensions creates a complex o...
Citation Formats
H. C. Önel, “Numerical simulations of wind turbine wake interactions using actuator line and les models,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Aerospace Engineering., Middle East Technical University, 2019.