Yatay eksenli rüzgar türbini palasının dinamik analizi
Dynamic analysis of a horizontal axis wind turbine blade
Yazar: SERAP BAYTOK
Danışman: PROF. DR. METİN ORHAN KAYA
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Uçak ve Uzay Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 2012
Konu: Enerji = Energy

Özet:
Günümüzün en hayati önem taşıyan meselelerinden bir tanesi : ihtiyaç duyulan ve vazgeçilmez olan enerjinin sürekli, kaliteli ve güvenli olarak sağlanabilmesidir. Malesef fosil yakıtlar dünya genelinde, gerek ısınmada gerekse yakıt olarak çok geniş bir kullanım alanına sahiptir.Rüzgar enerjisinin kullanılabilmesi, rüzgar rejimine, rüzgar milinin yerleştirildiği yüksekliğe ve enerji üretim sisteminin boyutlarıyla ilişkilidir. Rüzgar enerjisi gibi alternatif enerjiler sayesinde, kömür ve petrol gibi ithal enerji kaynaklarına bağlı olarak üretim yapan ülkelerde kendilerine yeter hale gelebilirler. Rüzgar enerjisinin kullanımının faydaları aşağıdakiler gibi özetlenebilir. Öncelikle rüzgâr enerjisi temizdir. Gürültü kirliliği haricinde herhangi bir çevre kirliliği yaratmaz.Rüzgar enerjisi göreceli olarak iş gücünün yoğun olduğu ve yeni iş olanakları yaratan bir alandır. Rüzgar enerjisi uzak veya şebekenin yaygın olmadığı bölgelerde depolamak üzere veya dizel motorla birlikte kullanılarak yakıt tasarrufu sağlamaktadır.Yenilenebilir enerji kaynakları arasında rüzgâr enerjisi özellikle son yıllarda ilgi görmekte ve gelişmektedir. Günümüze gelene kadar rüzgar enerjisi, kırsal alanda elektrik enerjisi elde etme ve su pompalama amaçları ile kullanım alanı bulmuştur.Son yıllarda ise alternatif bir enerji üretim kaynağı olarak enerji sektöründe yerini almıştır. Rüzgâr türbinleri, rüzgârdaki kinetik enerjiyi önce mekanik enerjiye daha sonra da elektrik enerjisine dönüştüren sistemlerdir. Bu teknoloji, aerodinamik, meteoroloji, mekanik, elektrik gibi birçok konuyu içinde barındırır.Bu çalışmada yatay eksenli bir rüzgar türbini palasının dinamik analizi yapılmıştır. Rüzgar türbinlerinin tarihi gelişimleri incelenmiş, geçmişten günümüze katettikleri yolla birlikte gelişen teknoloji gözlenmiş, türbinlerin günümüzde sahip oldukları özellikler ve enerji üretimindeki önemleri belirtilmiştir. Rüzgardan enerji elde ediminin önemli parametreleri gözden geçirilmiş, Türkiye'nin rüzgar enerjisi potansiyeline değinilmiştir.Yatay eksenli bir rüzgar türbininin hareket denklemlerini çıkarabilmek adına türbine etki eden kuvvetlere değinilmiş ve kuvvetlerin denklemleri türetilmiştir. Türbin palasının flaplama(aşağı-yukarı), lead-lag(ileri-geri) ve feathering(yunuslama) hareketleri incelenmiş, bu hareketleri oluşturan kuvvetler belirlenmiş ve hareket denklemleri türetilmiştir.Temsili olarak 8.4 metrelik bir rüzgar türbini palası üzerinde kuvvetler örneklendirilmiştir. Türbin değişik hızlarda operasyon yaptığında, değişik açılarla yaw(türbinin başını rüzgar yönüne dönmesi) hareketi sergilediğinde ve çapraz yönden esen değişik hızlardaki rüzgara maruz kaldığında palanın davranışı eğilme momentleri gözlemlenerek incelenmiş ve sonuçlar çıkarılmıştır.

Abstract:
One of the most important issues of our time is the secure, sustainable and quality supply of the world?s energy requirements. Fossil resources have a considerable role in the global demand of fuel and energy. Also fossil fuel resources are unevenly distributed with certain countries enjoying ample reserves while other consuming nations have very limited supply of these resources. The finite nature of this supply source, the environmental constraints and the significant financial requirements of developing fossil resources are forcing most nations to review their energy strategies and to take urgent measures to reduce their dependency on this energy source. These measures can be classified as follows: reducing the share of petroleum in the energy mix; energy preservation and more efficient use available energy resources; development of renewable energy sources and implementation of attractive new technologies. The development of wind power engines among alternative renewable energy sources has been phenomenal in recent years. Traditionally, wind power was harnessed for energy supply to remote rural areas and especially for driving water pumps. More recently, however, the more widespread use of wind power as an alternative energy source has emerged in most countries taking its place as a more predominant contributor in the energy sector.Wind turbines are systems designed to convert the kinetic energy found in the wind into first mechanical energy and then into electricity. The technologies involved mainly include aerodynamics, meteorology, mechanics, and electricity. The viability of wind energy is related to various factors including the wind regime, the wind tower height and the nature of the energy productions systems. These variables also depend on each other; for example wind speeds increase with altitute, so the higher the tower, the higher the speeds that can be harnessed from the wind. Countries that have favorable wind resources are particularly interested in these technologies since wind energy solutions can contribute to a country?s desire to reduce dependence on imported resources such as coal and petroleum in quest for self-sufficiency. The advantages provided by wind energy can be summarized as follows.Wind energy is classified as a relatively clean energy. Aside for its noise characteristics, wind energy does not generate any environmental pollution. A modern 600kW wind turbine can be a substitute for a coal fired power plant that would otherwise generate about 1200 tons of carbondioxide yearly.Furthermore, wind energy is an aboundant and renewable energy source in countries which are favorably located for it. Turkey is well endowed with wind energy resources and can develop this energy source to reduce its dependence on imported energy sources. Wind power facilities typically occupy 1% of the spaces where they are located. The energy required to erect a wind turbine facility can be recouped in a period as short as 3 months. For countries like Turkey that present such immediate and growing demand for energy, this is also an attractive feature of the resource. The development of new wind energy technologies and the implementation of wind farms can also create opportunities for a qualified workforce. In the areas where ample wind resources are available, wind energy production can be very competitive on a price per kwh produced with other conventional energy sources. In areas where the electricity networks are remote, wind energy can be used to complement diesel engines for improving fuel efficiencies. In certain coastal regions which do not have sanitary drinking water, wind turbines can be used to desalinate sea water.One of the objectives of the energy sector is to increase the competitiveness of the wind turbines and wind projects. In order to increase efficiencies, turbine designers and manufacturers have focused on reducing production as well as other costs involved in the implementation and operation of wind projects. Efficiencies are measured in the ultimate cost of the electricity produced which mainly depends on factors such as the characteristics of the wind resource, the cost of the land on which the turbines are based, and other financial factors. Feasibility studies for each wind project are based on projections. The design characteristics of the wind turbines are used in combination with the wind speed, direction, and regime profiles gathered through surveys conducted for each target area. Based on these projections, engineers can assess the quantity, nature and profile of the electricity to be produced by each designed turbine.Most of the costs associated with wind energy are the initial investment costs in the equipment and the installation of wind turbines. Coal or oil powered production plants rely on expensive feedstock to produce electricity. Hydroelectric plants rely on water, which is a renewable resource as well but also can be sold on its own for irrigation or other uses. Since wind is mostly free, once the projects are implemented no additional fuel expenses are necessary for generating electricity. But unlike water, coal or oil, wind cannot be stored. Wind energy projects depend on a constant and reliable flow of wind to be feasible. Weather forecast are an integral part of wind projects. As the cost of wind turbines are the most important aspects of the investments and on-going operations of wind projects, turbine design that optimizes the use of available wind resources becomes the most critical aspect of the development of wind energy.Wind turbines when in operation produce noise. In densely populated areas, these noise levels can be troublesome. In modern wind turbines, noises generated by mechanical equipment have been mostly reduced. Meanwhile, work on reducing the aerodynamic noises related to the blades continues. Furthermore, as technologies improve, the production capacities of modern turbines are constantly increasing with higher capacity larger turbines replacing those with smaller capacities. Certain wind mills and their turbines are thought to change the landscape and disturb the appeal of picturesque regions. Therefore, if a wind project is to be implemented, it is necessary to receive the approval of local populations affected by the new developments. Offshore wind turbine technologies are also being developed rapidly and these can be positioned in remote areas. In these cases, developers can be less concerned with disturbances to regional populations living in the vicinity of the wind facilities.In other words, wind turbines will produce electricity as long as the wind blows at the required speeds with the desirable characteristics. When wind speeds and characteristics are no longer ideal, the turbines will stop and the energy cannot be generated. This is why wind energy cannot on its own meet the requirements of the energy sector as a reliable continuous supply of ample energy. Instead, wind energy is one of the alternative supply sources in the overall energy mix. Nevertheless, wind energy remains one the most attractive source of clean energy due to its other characteristics. Turbine designers? objective is to can maximize electricity production for the given wind characteristics which often push them to create turbines with higher towers, greater capacities, better overall efficiencies and with lower manufacturing and operating costs.Countries that possess diversified and well balanced energy supply sources can most effectively utilize their electricity generation capacity. Typically, energy efficient countries benefit from highly developed electricity grids where alternative energy sources can be commissioned and added back and forth effectively. Although efficient designs shall maximize the output of electricity from a given installed capacity and wind energy resource, the electricity transmission and distribution system, the grid, should also be planned and developed to match the supply with the demand profile for electricity.In this study, the dynamic analysis of a horizontal wind turbine blade is investigated. After an introduction to the historyof wind turbine development, its technological progress is reviewed, and the characteristics of current wind turbines and their role in energy production is presented. The parameters involved in wind energy are considered and the wind energy potential of Turkey is put in perspective.In order to derive the equations of motion of a horizontal axis wind turbine blade, the forces acting on the blade is explained. After analysing blade motion behaviors like flapping, lead-lag and feathering,the forces causing these motions are determined.In the study, the forces acting on a 8.4 meter long wind turbine blade areconsidered as an example. Forces acting on the blade due to flapping, lead-lag and feathering are observed. Different operating situtations like, slow-fast rotating, yaw ratio, crosswind speed and pitch angle are studied by observing moments of bendings.