Sharif Digital Repository

Considering the negative effects of contamination on wind turbine blade performance, we investigate aerodynamics performance of a one- Megawatt wind turbine. To achieve this, we compare the performance and power of the wind turbine with and without contaminations. To calculate the wind turbine output power, we use a developed wind turbine calculator, which benefits from the Blade Element Momentum (BEM) theory. Furthermore, the aerodynamics calculations are performed using of a commercial software for clean and rough airfoils. Considering the change of Reynolds number along the blade axis, the airfoil characteristics are calculated for two Reynolds numbers of 0.5 and 3.5 millions to increase... 

An aerodynamical model for studying asymmetric and three-dimensional flow fields about wind turbine rotors is presented. The developed algorithm combines a asymmetric and three-dimensional Navier-Stokes solver with a so-called actuator disc technique in which the loading is distributed along lines representing the blade forces. The loading is determined iteratively using a bladeelement approach and tabulated airfoil data. Computations are carried out for a 5MW NREL wind turbine equipped with three blades. The computed power production is found to be in good agreement with measurements. The computations give detailed information about basic features of wind turbine wakes, including... 

The power control of horizontal axis wind turbines can affect significantly the vibration loads and fatigue life of the tower and the blades. In this thesis, we are going to consider both the power control and vibration load mitigation of the tower fore-aft vibration. For this purpose, at first, we developed a fully coupled model of the NREL 5MW turbine. This model considers the full aeroelastic behavior of the blades and tower and is validated by experiment results, comparing the time history data with the FAST (Fatigue, Aerodynamics, Structures, and Turbulence ) code which is developed by NREL (National Renewable Energy Lab in the United States). In the next, to estimate EWV, a novel... 

In this study, the two rigid body modelling of a Coanda air vehicle (one rigid includes rotor and propeller and the second rigid includes the other parts of it) has been developed using Newton’s and Euler’s laws, and its motion was simulated in climb and forward flight conditions. Air vehicle propulsion force and moment have been modelled by employing the blade element momentum theory. In order to model the forces acting on the air vehicle, the drag force has been estimated by the results of analytical and computational fluid dynamics methods for the case of climb flight and by using experimental data of a cylindrical body for the forward flight. For modelling the control surfaces of this... 

The issue of solid and fluid interaction in horizontal axis wind turbines with diameter of more than 120 meters is one of the most important researching subjects of this type of turbines. This issues needs quick and exact solutions because of the high computational cost of fluid and structural domains.In this research a quick method with acceptable accuracy has been suggested which is based on computational fluid dynamic to examine the aeroelastic behavior of rotor and wind turbine tower. The actuator disc method in two domains of axisymmetric and three-dimensional has been used to compute aerodynamic forces. For this purpose a code has been written in C++ to set down virtual momentum on... 

In this Thesis, an unmanned multicopter with a new structure is modeled and a nonlinear controller is designed for it to track the trajectories precisely. The multicopter in this thesis, has six propellers with a hybrid propulsion system (a combination of fuel and electric propulsion system) that has the ability to carry more payload and maintain more flight duration compared to electric multicopters. In the beginning, the performance characteristics and technical specifications of the hexacopter are presented. For modeling, first the equations of six degrees of freedom movement of the hexacopter are derived by the Newton-Euler method. In the next step, the forces and torques applied to the... 

Recent decades have seen a growing demand for high-power wind turbines resulting in turbines with larger blades and the advent of high-megawatt wind turbines. The blades of the megawatt-scale turbines experience more complicated flow phenomena compared to those of the smaller-scale wind turbines. Needless to say, the importance of an accurate solution and detailed analysis of all the parameters, including blades aerodynamic and aeroelastic performance as well as fluid-structure interaction, is more significant for the megawatt-scale turbines compared to smaller-scale turbines. The conventional methods of aerodynamic solutions for the blade, including analytical methods, such as BEMT78 and...