Experimental and Numerical Investigation of the Effect of Newly Tested Blades on the Aerodynamic Performance and Power Output of a Horizontal Axis Wind Turbine

There is no doubt that the effects of global warming are obvious for every human being on the Earth now. Therefore, the need to develop carbon dioxide-free sources of electricity is urgent. Wind Turbines are one of these most essential recently developed sources. For that reason, the University of Wisconsin-Milwaukee founded the wind tunnel lab., equipped with the state-of-the-art research tools, to take part in this procession.In chapter (3) of this thesis it is desired to investigate in detail the scenario that takes place behind a single wind turbine unit by focusing on three parameters; average axial wind velocity component, velocity deficit, and total turbulence intensity. The testing was done at mainstream velocity, U∞, of 5.2 m/s, u and v velocity components were captured by x-probe dual-sensor hot wire anemometer. A massive amount of point data was obtained, which then processed by a Matlab script to plot the desired contours through the successive transverse sections along the entire length of the test section. By monitoring the previously mentioned flow parameters, the regions of low velocity and high turbulence can be avoided while the location of the subsequent wind turbine is selected. The estimation of the distance, at which the inlet flow field will restore its original characteristics after being mixed through the rotor blades, is very important as this is the distance that should separate two successive turbines in an inline configuration wind farm to guarantee the optimum performance and to extract the maximum power out of the subsequent array of turbines. It is found that the hub height axial velocity recovery at six rotor diameters downstream distance is only 82%. This means that the power extraction out of the downstream turbine in an inline configuration wind farm is only 55% of the upstream turbine, if the same free stream velocity and blade design are adopted. Then, chapter (4) sheds light on wind farm layout design, site evaluation, and power output prediction by performing modeling and the experimental tests of a wind tunnel test section including a single wind turbine model inside was created and validated against present experimental data of the same model. The Large Eddy Simulation (LES) was used as a numerical approach to model the Navier-Stokes equations. The computational domain was divided into two areas; rotational and stationary. The unsteady Rigid Body Motion (RBM) model was adopted to represent the rotor rotation accurately. It is concluded through this investigation, if the rotational speed control is adopted, that the wind velocity increase enhances the axial velocity recovery. Hence, the separation distance between two successive turbines decreases while maintaining the same level of power extraction. This way, we can optimize available site exploitation. After that, chapter (5) of this work tries to popularize the use of residential-scale wind turbines because the last few decades witnessed a great development for the large-scale wind turbines, while small-scale wind turbines didn’t grab the same amount of interest. On this track, four airfoils (GOE 447, GOE 446, NACA 6412 and NACA 64(3)-618) characterized by their high published lift-to-drag ratios (161.3, 148.7, 142.7 and 136.3 respectively) are used to generate an entire 7 m long blades for three-bladed rotor wind turbine models tested numerically at 12.5 m/s rated wind speed, with design tip speed ratio of 7. The criterion to judge each model’s performance is the power output. Thus, the blades of the model which produce the highest power are selected to undergo a leading-edge modification (tubercles), and a tip modification (winglet), seeking power improvement. Finally, the best basic model is tested at a spectrum of tip speed ratios (5 to 7.5, with 0.5 step) to find the optimum tip speed ratio. Moreover, chapter (6) highlights that Most of the available research work of horizontal axis wind turbines is focused on either lab-scale (15-60 cm rotor diameter) or commercial large-scale (80-130 m rotor diameter). There is a lack of published data on residential-scale turbines. The current work fills this gap because residential-scale turbines will be one of the key technologies during the next ten years since the current administration promotes dependence on renewables to cut carbon footprint. Therefore, the current work runs wind tunnel experimentation and performs 48 numerical simulations to evaluate the performance of a residential scale wind turbine with a blade generated from GOE 447 airfoil at three wind speeds (7.5, 12.5, and 17.5 m/s). Three different vortex generator designs were tested numerically when added on the suction side of a 7 m blade. Two of those designs produced more power than a baseline rotor does (7.2% and 10.9% more power than the baseline rotor were achieved at 12.5 m/s wind speed). Furthermore, three winglet designs were added to the baseline design to investigate their effect on power production. The 90o, 60o, and 30o cant angles produce 5.0%,7.9% and 6.9% more power than the baseline design, respectively. It was very important to investigate the effect of combining the most successful vortex generator and winglet design on the performance of a single blade. Combining both techniques impairs the functionality of each other, leading to a deteriorated overall performance and less power (generally 6% to 8% less power than the baseline design). Furthermore, chapter (7) utilizes wind tunnel experimentation and uses CFD simulations to evaluate the performance of a 14 m-rotor diameter residential scale wind turbine at three wind speeds (7.5, 12.5, and 17.5 m/s). The blades of the rotor baseline design are built using GOE 447 airfoil. Five different tubercle designs were applied to the blade’s leading edge. One of those designs produces more power than a baseline rotor, with an optimum power improvement of 5.5% achieved at 12.5 m/s wind speed. Furthermore, three winglet designs were added to the tip of baseline design to investigate their influence on the power production. The 90o, 60o and 30o cant angles produce 5.0%,7.9% and 6.9% more power than the baseline design, respectively, at 12.5 m/s. Moreover, it is vital to investigate the effect of integrating leading-edge tubercles with winglets, then evaluate the influence of the combination on the aerodynamic performance and power output of the turbine model. It is found that when combining both techniques on the same blade, the improvement mechanism associated with each of them interferes with the other, leading to poor overall performance and less power in the majority of the run simulations. Finally, chapter (8) highlights the topics that have potential for future work

An Investigation of Less Export of Readymade Garments to Non-Traditional Markets by Bangladesh and Justification of Increasing Export

This paper focuses on the current condition of readymade garments export by Bangladesh to well-established export destinations and nontraditional destinations. The main objective of this study is to find out ways of increasing Bangladesh’s export earnings. The RMG industry has set an export target of US $50 billion by 2021 for which new export destinations must be explored. Bangladesh, however, is still far behind the target due to some constraints. Another objective of this study is to identify these constraints and justify the reasons to explore the non-traditional markets. This study was conducted using secondary data obtained from various trusted national sources. These data were analyzed and showcased using statistical tools to interpret the discussed topic

Judicial enforceability of economic, social and cultural rights in Bangladesh : a critical evaluation

The implementation of economic, social and cultural rights (esc rights) continues to pose uncertainties in the modern world. Given that many states constitutionally treat such rights as aspirational and not justiciable, it is difficult to enforce them judicially at the domestic level. Bangladesh has embodied these rights in Part ii of its Constitution as a social welfare goal of the State. This article takes Bangladesh as a case study and examines the international legal framework for the implementation of esc rights at the domestic level. Making a comparison with other jurisdictions, such as India and South Africa, the article examines the approach of the judiciary of Bangladesh (the Supreme Court) in giving effect to these rights. Lastly, the article argues that the court should devise appropriate and effective enforcement mechanisms for these rights

A review of methods and models of technology transfer

Technology transfer is a complex and sensitive process, if not conducted through awareness and research will entail hefty and immense costs and losses. Since the audience of this process are mostly in developing countries, it can be stated that studying and investigating the trend of most technologies transferred to the developing countries commonly indicates the weaknesses that due to unawareness of the conditions and existing needs and also policies and objectives the technology transferors follow could lead to irreparable failures, thus inhibiting the applicant from accessing the technology itself. The importance of technology transfer and its role in the industrial development of countries and filling of the technology gap between the developing and developed countries is inevitable. Technology transfer is conducted in various ways based on the conditions of the receptors and donors of technology. In this paper, the process of technology transfer and types of relevant methods that would lead to effective technology transfer are going to be elaborated. Also, models related to technology transfer will be examined

Variability in Eggplant (Solanum melongena L.) and Its Nearest Wild Species as Revealed by Polyacrylamide Gel Electrophoresis of Seed Protein

A study was undertaken to determine and distinguish the genotypes of eggplant (Solanum melongena L.) and its nearest wild species by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE) of soluble seed proteins. Fifty four accessions of cultivated and wild groups of eggplant were subjected to the analysis. The results of electrophoretic banding patterns show that there was a great deal of variation within and between groups of eggplant in terms of numbers, sizes, positions, staining intensities and presence or absence of protein bands in the profile, which can be used for characterization and identification of eggplant cultivars. Elongated fruit eggplant cultivars exhibited nine common group-specific bands which distinguish them from the other groups. Meanwhile, a great variability in seed protein profiles was detected in the round fruit type and primitive cultivars, weedy and wild groups of egg plant including the truly wild S. incanum, which indicated that these groups consist of diverse genotypes

The effect of garlic extract on growth, haematology and cell-mediated immune response of newborn goat kids

The present study was carried out to evaluate the effect of different levels of garlic extract supplemented in milk on growth rate, haematology and cell–mediated immune response of Markhoz newborn goat kids. Twenty four newborn goat kids (aged 7+/-3days) were randomly assigned to four groups. The groups consisted of control (received milk without garlic extract), T1, T2 and T3 which received milk supplemented with 62.5, 125 and 250 mg aqueous garlic extract per kg live weight per day for 42 days, respectively. Body weights were measured weekly throughout the experimental period. At day 42, about 10 ml blood samples were collected from each kid via the jugular vein for haematological study. Cell–mediated immune response was evaluated through double skin thickness after intradermal injection of phyto-hematogglutinin (PHA) at day 21 and 42. Total gain was significantly higher for kids in T3 (P0.05) compared with the control group. Average daily gain (ADG) in T3 group in week 4–5 was higher (P0.05). Significant differences in globulin (P0.01), hemoglobin (Hb; P0.001), hematocrit (PCV; P0.001), erythrocyte (RBC; P0.001), neutrophil (P0.001), lymphocyte (P0.001) and leukocyte (WBC; P0.001) were observed among groups. Hb, PCV, RBC, lymphocytes and WBC were higher in kids given garlic extract supplementation. There was a significant difference of double skin thickness among the groups at day 42 (P0.01). In conclusion, this study indicated that milk supplemented with aqueous garlic extract improved growth rate and immunity of newborn goat kids

Ballisticity of nanotube FETs: Role of phonon energy and gate bias

We investigate the role of electron-phonon scattering and gate bias in degrading the drive current of nanotube MOSFETs. Our central results are: (i) Optical phonon scattering significantly decreases the drive current only when gate voltage is higher than a well-defined threshold. It means that elastic scattering mechanisms are most detrimental to nanotube MOSFETs. (ii) For comparable mean free paths, a lower phonon energy leads to a larger degradation of drive current. Thus for semiconducting nanowire FETs, the drive current will be more sensitive than carbon nanotube FETs because of the smaller phonon energies in semiconductors. (iii) Radial breathing mode phonons cause an appreciable reduction in drive current.Comment: 16 pages, 1 table, 4 figure