Hava kanallı rüzgar türbini kanat tasarımının aerodinamik verime etkisinin deneysel incelenmesi
Experimental investigation of the effect of air ducted wind turbine design on aerodinamic efficiency
Yazar: ADEM AKIN DURAN
Danışman: DOÇ. DR. CEMİL YİĞİT
Sakarya Üniversitesi / Fen Bilimleri Enstitüsü / Yenilenebilir Enerji Sistemleri Ana Bilim Dalı
Derece: Yüksek Lisans, 2024
Konu: Enerji = Energy

Özet:
Rüzgar enerjisi, temiz ve yenilenebilir bir enerji kaynağı olarak dünya genelinde önemli bir yer tutmaktadır. Bu enerji kaynağını elektrik enerjisine dönüştürmek amacıyla kullanılan rüzgar türbinlerinin verimliliği, özellikle kanatların aerodinamik performansına bağlıdır. Kanatlar üzerindeki basınç ve viskoz kuvvetler, türbinin rotorunda üretilen torku doğrudan etkiler. Bu çalışmada, kanatlara açılan hava kanallarının viskoz kuvvetler üzerindeki etkisi incelenmekte olup ve optimum performans için ideal hava kanalı sayısını belirlenmiştir.
Çalışmada öncelikle hava kanalı bulunmayan bir kanat tasarlanmış, ardından 5, 10 ve 15 hava kanallı kanatlar deneysel olarak incelenmiştir. Her kanat geometrisi için elde edilen verilerle güç katsayıları hesaplanmış ve karşılaştırılmıştır. Aynı jeneratör üzerinde ve aynı yataklama sistemi kullanılarak farklı hava kanalı sayılarına sahip kanatlar çalıştırılmıştır.
Güç katsayısı belirlenirken, kanata etki eden rüzgar hızı, jeneratör çıkış gerilimi ve çıkış akımı gibi parametreler ölçülmüştür. Rüzgar hızı ölçümü için kanat önüne anemometre yerleştirilmiş ve jeneratör çıkışındaki gerilim ve akım parametreleri deney düzeneğiyle ölçülmüştür. Her kanat için güç katsayıları, farklı açısal hızlarda incelenmiş ve bu verilere göre analiz edilmiştir. Türbin kanatına ait açısal hızın belirlenmesi için jeneratör çıkış frekansı ölçülerek senkron makinelere ait senkron hız eşitliği kullanılmıştır. Rüzgar kaynağının çalışma frekansı bir sürücü yardımıyla değiştirilerek kanat üzerinde farklı rüzgar hızları elde edilmiş ve türbin kanatının farklı açısal hızlarda dönmesi sağlanmıştır.
Taguchi metodolojisi kullanılarak, hava kanalı sayısı ve kanat açısal hızı kontrol edilebilir değişkenler olarak seçilmiş ve optimum kanat tasarımı belirlenmiştir. Açılan hava kanallarıyla beraber kısmi basınç kuvveti kaybı yaşansa da, ekstra viskoz kuvvetlerle kanat performansı arttırılmıştır. Hava kanalsız kanat ile kıyaslandığında daha düşük açısal hızlarda yaklaşık %1'lik bir performans artışı tespit edilmiştir.
Sonuç olarak, aerodinamik optimizasyon ve viskoz kuvvetlerin etkili kullanımıyla tasarlanan hava kanallı kanatlar, rüzgar enerjisi türbinlerinin verimliliğini artırmak için önemli bir potansiyele sahiptir. Gelecekteki çalışmalar, farklı hava kanalı düzenlemelerinin ve aerodinamik iyileştirmelerin daha da verimliliği artırıp artıramayacağını incelemeye odaklanabilir. 
Bu metin, rüzgar enerjisi teknolojilerindeki mühendislik çalışmalarının önemini vurgulayarak, yenilenebilir enerjiye yönelik sürdürülebilir çözümler arayan araştırmacılar ve endüstri uzmanları için bir kaynak sağlamaktadır.

Abstract:
Electricity generation from wind energy has become increasingly popular in our country and around the world in recent years. This intense interest in wind energy has led to an increase in studies on wind turbine performances.
The aerodynamic performance of the wing is extremely effective on the power produced by wind turbines used to obtain electrical energy from wind energy. Pressure and viscous forces on the blade have a direct effect on the torque produced in the rotor. In this study, the effect of changing viscous forces on the wing performance was investigated, although there was a decrease in the pressure force acting on the wing by opening an air channel on the wing. As a result of experimental observations, the optimum number of air ducts that can operate at optimum angular speed was examined. In determining the optimum wing design, the largest power coefficient value (C_p) of the wings was taken into account.
Within the scope of this thesis, an experimental setup was created to examine the performance of wings without air ducts, with 5 air ducts, with 10 air ducts and with 15 air ducts. The wings, which differ only in the number of air channels, are coupled to the synchronous generator via the same bearing device, and the same load is connected to the generator output for each wing design. The load connected to the synchronous generator output was chosen to allow the wide operating speed range of the generator.
During the experiment phase, electrical outputs read from the generator were used to determine the power coefficient (C_p) and angular velocity values of the wind turbines. Since the power coefficient value is the ratio of the power obtained in the turbine rotor to the power that can be obtained from the wind, the wind speed to which the blade was exposed was measured by placing an anemometer in front of the blades to determine the wind power. Thus, since the area swept by the wing was known, the wind power acting on the wing was found by using the cube of the wind speed. While calculating the power in the turbine rotor, generator internal impedances and line impedances were neglected and the power drawn from the delta connected load was taken as reference. Neglecting friction and wind losses, core losses, copper losses and other losses, the mechanical power of the generator rotor is considered equal to the electrical power measured on the load. For the electrical power measured on the load, measurement was made on one phase since the system works with a balanced and three-phase load. The generator output voltage was measured with the help of a voltmeter connected in parallel to the load, and the output current was measured with the help of an ammeter connected in series with the load. Generator output power was found using the measured parameters. The measuring instruments used are those that measure RMS quantities.
While determining the speed of the rotor blades, the synchronous speed formula used in synchronous generators was used. The synchronous speed formula gives information that the output frequency changes according to the rotor speed in generators with a known number of pole pairs. When the synchronous speed formula is rearranged, the speed information in rpm of the generators whose frequency is measured can be obtained. Since it is known that the synchronous generator used in this experimental study has 6 pole pairs, the turbine rotor speed was determined using the frequency value measured at the generator output. The determined data were converted into cycles per second and used in the study.
When the experimental data were examined, it was seen that the wing with 5 air ducts reached lower speeds at the same wind speed compared to the wing without air ducts. In addition, the maximum power coefficient it produces is lower than the wing without air ducts. The largest power coefficient produced for the wing with 10 air ducts is almost the same as the largest power coefficient of the wing without air ducts. It has been observed that the wing with 15 air channels has a largest power coefficient slightly higher.
Using the data obtained, power coefficient graphs corresponding to the number of revolutions were created for each wing. When the graphs are examined, it is seen that a different polynomial trend line is formed for each wing. This has shown that while the power coefficient value of the air ducts opened in the wings changes, it also causes changes in the working regions of the wings. Taking the largest power coefficient value of the wing without air ducts as a reference, a polynomial trend line was created for the points where the wings with air ducts gave the largest power coefficient. Based on the trend line, a prediction can also be made for a wing design with 20 air ducts. It was estimated that the power coefficient for the wing with 20 air ducts would produce a lower power coefficient than the design with 15 air ducts. Using the trendline equation, it was found that the peak value of the trendline would result in the largest power coefficient for the 13 air duct design.
Since this thesis is the product of an experimental study, the availability of measurement instruments used to obtain data in the experiments made error analysis necessary. By determining the criteria used when determining the experimental data, an attempt was made to reach conclusions about the degrees and amounts of errors. The error values of the measured quantities were calculated theoretically, assuming that there was no error during the manufacturing of the measuring instruments used in the experiment, and using the error values promised by the manufacturer companies and experimental experiences. As a result, there is an uncertainty of 4.3% for the power coefficient (C_p) values obtained as a result of the measured experimental parameters.
It was decided to use the Taguchi method to find the most optimum solution for turbines with blade designs. For the designed turbine blades, blade design and blade angular speed that may affect the electrical power obtained from wind energy are discussed. The number of air channels on the rotor blade and the rotor angular speed were selected as controllable factors. The controllable variable was intended to be optimized with relatively less experimental work using the Taguchi method.
The optimization phase was started by using the test data obtained from the experimental setup. Two-parameter four-level Taguchi method was used for optimization. The first parameter was the number of air ducts designed before the experiment, while the second parameter was determined as the angular speed values of the wind turbine.
In this study, the effect of the number of air ducts and angular velocity on wind turbine blades on blade performance was determined using the Taguchi method. According to the Taguchi method, it has been determined that the wing with 15 air ducts has the most efficient operating state when operating at a speed of 6 rps. The operating conditions and wing design obtained as a result of optimization can operate with 15.13% efficiency in the system.
Air ducts opened in the wing cause a decrease in the air pressure acting on the wing. It also changes the viscous forces acting on the wing. According to the measurement values, the wing with 5 air channels gives the largest power coefficient (C_p) value of 0.1336 at an angular speed of approximately 6.6 rps. The wing with 10 air channels gives the largest power coefficient (C_p) value of 0.1502 at an angular speed of approximately 6.3 rps. The wing with 15 air channels gives the largest power coefficient (C_p) value of 0.1508 at an angular speed of approximately 6.2 rps. The largest power coefficient for the wing without air ducts is approximately 0.1498 at 6.8 rps.
When the results are examined, it is seen that the air ducts opened in the wings change the working regions of the wings. It is seen that the air ducts opened in the wings first reduce the power coefficient value, and then, as the number of air ducts increases, the power coefficient increases. It has been observed that the increase in the number of air ducts in the designed wings brings the region where the wings have the largest power coefficient to lower speeds.
As a result of the optimization, it was determined that the design with 15 air ducts had a performance increase of approximately 1% at 6 rps compared to the design without air ducts. For the area swept by the wing used in this study, there is approximately 142 W energy in the wind beam with a speed of 8 m/s. This 1% increase in the power coefficient provides an additional 1.42 W energy gain in the generator rotor. In addition, the fact that the 15 air duct design gives the highest power coefficient value at lower speeds compared to other blades can prevent problems caused by noise and vibrations in terms of working conditions.