Numerical analysis of dynamic behavior of wind turbine blades with vertical axis by Eulerian coupled Lagrangian method

Dissertation for M.Sc. degree

Mechanical Engineering - Applied Design

In this research, the vertical axis wind turbine model Savonius is modeled. The wind turbine has been modeled in the fluid control volume, which is the same as the wind tunnel in real conditions, and has been checked under wind blowing with different speeds. Also, in terms of the overlapping ratio, it has been examined in three different modes to determine the best state of the turbine with the optimal static torque.

Unlike all the researches, the method presented in this research is the modeling of the fluid collision with the turbine blades, which allows checking the dynamic behavior and calculations of the stress and strain on the turbine blades.

The results of this research show It means that in areas where the wind speed is low, a turbine should be used with a low phase angle between two turbine floors, and in areas where the wind speed is high, a large phase angle should be used. Also, in order to reduce the fluctuations of the angular speed of the turbine rotor, in the areas where the wind speed is high, a larger phase angle should be used. However, in areas where the wind speed is lower, a smaller phase angle should be used.

The complete modeling of the fluid interaction on the turbine blades shows that the static torque increases at the moment the rotor starts to rotate, due to the presence of the bearing in real conditions, but after the motion starts and the static friction force is overcome, the torque gradually decreases. This value reaches its minimum at an angle of about 85 degrees, at which moment the turbine will have its highest speed.

Also, the kinetic energy diagram and the whole turbine have been examined, which shows the increase of these values ??due to the increase in wind speed for all turbines and the increase in the phase angle for two-story turbines. It is given that there is an acceptable agreement between these results.

Key words: vertical axis wind turbine, phase angle, overlap ratio, Sauvignon turbine, finite element analysis

Introduction

Due to the increasing need for energy resources and the reduction of fossil fuel resources and the necessity of keeping the environment healthy, reducing air pollution, electricity supply limitations and fuel supply for remote rural areas, etc., the use of new energies such as water energy, wind energy, solar energy, hydrothermal energy, and so on. It can have a special place. With the development of environmental attitudes and economical strategies in the exploitation of non-renewable energy sources, the use of wind energy compared to other energy sources has increased in many countries of the world. Using wind turbine technology can be a good choice compared to other renewable energy sources.

In turbines with vertical axis rotors, the axis of rotation is perpendicular to the surface of the earth and the rotation of the blades is parallel to the earth, and for this reason the surface that is moved by the wind After half a turn, the aircraft has to continue moving in the opposite direction of the wind flow, and this problem causes their power factor to drop. For this reason, blade design is of particular importance in these rotors.

Until now, many studies have been conducted in the field of wind turbines, but all these studies were mostly obtained in the laboratory due to the complexity of wind turbine design. Of course, the level of studies has also been limited.

Therefore, in this research, the interaction of wind on turbine blades has been modeled in the software and numerically analyzed by the finite element method, and the results obtained from the numerical analysis have been compared with the experimental results. The concordance of these results shows the correctness of the numerical results..

In the first chapter, the definition of renewable energy and its types have been discussed. Then, considering that the topic of the thesis is specialized on wind energy, a brief history of the uses of wind energy throughout history has been stated, and then the types of wind turbines that include vertical and horizontal axis have been examined and their merits and demerits have been discussed. In chapter 2, he explained the latest article on the interaction of wind on turbine blades and then various theories that scientists have related to turbine power factor and . have presented, it will be checked. In chapter 3, fluid-structure interaction modeling for dynamic simulation of Sauvignon turbine is presented. In chapter 4, the results of numerical analysis are presented by presenting different diagrams such as static moment diagram, power coefficient and . will be reviewed. In the last chapter, by summarizing the results obtained in the thesis, suggestions for further research will be presented. Chapter 1: Introduction 1-1 Introduction style="direction: rtl;">Mankind's increasing need to consume energy on the one hand and the need to preserve and protect the living environment against the consequences of fossil fuels on the other hand, has led to the attention of clean energy sources more than ever before. Renewable energy systems include the most prominent sources of clean energy. The consequences of environmental pollution caused by fossil fuels have become so widespread today that mankind regrets the past actions and the unstable and heterogeneous development built on it, and is looking for a way to escape from these conditions. But on the other hand, it is inevitable to continue the process of such development, because changing the culture in the use of technology, both in the production and consumption sectors, requires the passage of time and spending a lot of money. Therefore, many and increasing investments have been made, especially in developed countries, to study the growth and expansion of the use of renewable energies on the one hand in the production sector (on a large scale and in the power plant dimension) and on the other hand, culture building in the consumption sector, both in the field of using independent and clean scale energies and in the field of improving the consumption pattern. [

1-2- Renewable energy

Unlike fossil fuels, renewable energy sources are constantly created and can remain stable. Some of the most widely used renewable energy sources are: biomass energy [2] (such as wood and its waste, urban solid waste, biogas, ethanol, biodiesel, etc.), high-power energy [3] (such as water potential, ocean waves, etc.), solar energy, and wind energy.

Using renewable energy sources is not a new issue. More than 150 years ago, the use of fire energy as an example of biomass energy accounted for more than 90% of the total energy consumption. Today, we are still looking for ways to use renewable energy.

In 2006, nearly 18% of the world's total energy consumption was provided by renewable energy. Also, 13% of it is biomass energy, which is mainly for heating purposes, and only 3% of energy is hydroelectricity. Renewable energies (including: energy with partial high power, wind energy and solar energy, etc.) also accounted for 2.4%. The share of renewable energy in electricity production is about 18%, of which about 15% is related to hydro turbines and the rest is produced from other renewable energies. Europe's policy on electricity production from renewable energy is about 20% in advancing its goals.

In the summer of 2010, the member states of the European Energy Commission presented their plans and programs. The use of renewable energy in some countries was one of their national development goals. In Denmark, their policy and long-term goals are to reach 30% of electricity production from renewable sources by 2020.