Aerodynamics and self-starting of vertical axis windturbines with j-shaped aerofoils
Başlık çevirisi mevcut değil.
- Tez No: 760804
- Danışmanlar: PROF. LİN MA
- Tez Türü: Doktora
- Konular: Makine Mühendisliği, Mechanical Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2021
- Dil: İngilizce
- Üniversite: The Unıversıty Of Sheffıeld
- Enstitü: Yurtdışı Enstitü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: Belirtilmemiş.
Özet
Özet yok.
Özet (Çeviri)
In light of the continuously increasing level of greenhouse gases, global warming has led to many investigations into the different types of renewable energy technologies, in particular wind turbines. The small-scale H-type Vertical Axis Wind Turbine (H-type VAWT) has been selected as the scope of this thesis due to its several significant advantages over the more commonly adopted Horizontal Axis Wind Turbines (HAWTs). However, the self-starting capability of these types of turbines is still one of the main challenging aspects and this limits their utilisation for the small-scale power generation. Unless the causes that prevent the turbine to self-start are understood sufficiently and designed to overcome the self-starting problem, they may be unsuitable for small-scale power generation. Hence, the present thesis aims to provide a detailed understanding of the self-starting behaviour of the small-scale H-type VAWTs and shed more light on the literature of the self-starting research by conducting a comprehensive analyse considering various design parameters. The Computational Fluid Dynamics (CFD) simulations are utilised as a modelling approach after conducting the accuracy checks in order to obtain high fidelity analysis considering the reasonable accurate and computationally economic aspects. 2D-based turbine dynamic start-up simulations illustrate that not only lift force is required for the turbine to self-start but also the drag force contributes to the turbine torque generation at the critical turbine starting stage where the tip speed ratio ()<1. This finding encourages enhancing the positive contribution of the drag force by modifying the conventional aerofoil shape. In addition, the effect of the several physical properties, such as the moment of inertia, solidity, and the mechanical resistances on both the overall and the selfstarting performance of the turbine is investigated. In contrast with the conventional aerofoils, such as NACA0018, the resistive type, such as the J-shaped aerofoil, is investigated in detail to provide an in-depth understanding of the aerodynamic performance of these kinds of aerofoils considering the oscillating motion and whole turbine aspects. The investigation v of the J-shaped aerofoil under the oscillating motion, which is also a novel study for the J-shaped aerofoils, to highlight the advantages and disadvantages of the J-shaped aerofoils under the different operating conditions is found to assist in obtaining a further understanding of the aerodynamic characteristics of the Jshaped aerofoils when they are used in the turbine applications. In addition, the present work presents the first turbine time-varying start-up behaviour investigation for the turbine with the J-shaped aerofoils contrary to other studies in the literature. Even though the J-shaped profile increases the turbine performance in the upstream part of the turbine, increasing the opening length over the aerofoil surface causes a significant aerodynamic efficiency loss in the downstream part of the turbine, in particular when the turbine is rotating faster. Therefore, the utilisation of the optimum J-shaped profile is found to be of utmost importance not only to optimise turbine self-starting performance but also to maintain the performance efficiency at higher rotational speeds. Furthermore, this thesis proposed a novel hybrid blade design for the first time, which combines a conventional aerofoil NACA0018 and its cutting-off counterpart J-shaped aerofoil, to enhance the torque generation at the starting of the turbine with low tip speed ratio values, on the other hand, minimise the efficiency loss at the high values. Although the utilisation of the J-shaped aerofoil in the turbine configurations illustrates an increase in the torque generation at the low values compared to the conventional aerofoils, a hybrid blade configuration that allows using the J-shaped profile in some portion of the blade span is required to reduce the significant performance loss at high values due to the inherent shape of the J-shaped aerofoil. For this purpose, the 3D-based CFD simulations have been conducted for the different configurations of the hybrid blades with the various opening length percentage of the J-shaped aerofoil used. In contrast with the losses due to the J-shaped aerofoils, the hybrid blade designs, especially a design with the closed-tip, is found to be an appropriate selection in terms of a faster start-up time and a higher final rotational speed when the turbine reaches its steady-state conditions.
Benzer Tezler
- Yatay eksenli rüzgar türbinlerinin aerodinamik karakteristikleri
Başlık çevirisi yok
NEVİN SALAR
Yüksek Lisans
Türkçe
1986
Makine MühendisliğiErciyes ÜniversitesiMakine Ana Bilim Dalı
DOÇ. DR. TAHİR YAVUZ
- Küt cisimler etrafındaki dalga hareketinin vorteks metodu ile analizi
Başlık çevirisi yok
SERPİL ÖZKILIÇ
Yüksek Lisans
Türkçe
1987
Makine MühendisliğiErciyes ÜniversitesiMakine Ana Bilim Dalı
DOÇ. DR. TAHİR YAVUZ
- Çeşitli şekillerde düzenlenmiş iki silindir etrafındaki akım alanının incelenmesi
Investigation of the flow araund two circular cylinders in various arrangements
M.NEVZAT ÖZKAN
- Bir tip merminin hareketinin deneysel incelenmesi ve dış balistikte teorik bir yaklaşım
Theoretical and experimental investigation on external ballistic characteristics of a projectile
MEHMET AKÇAY
- Havacılıkta kullanılan bazı eksenel simetrik cisimlerin aerodinamik karakteristiklerinin teorik ve deneysel olarak incelenmesi
Theoretical and experimental investigation on aerodynamic characteristics of some bodies of revolution used in aeronautics
VEYSEL ATLI