The acoustic treatment and calibration of a new anechoic system for the Virginia Tech Stability Wind Tunnel has been performed. This novel design utilizes Kevlar cloth to provide a stable flow boundary, which eliminates the need for a free jet and jet catcher. To test this concept a series of measurements were performed both to validate the reduction in overall test section noise levels and to ascertain the effect of these modifications on the test section aerodynamics. An extensive program of experiments has been conducted to examine the performance of this new hardware under a range of conditions. These include baseline experiments that reveal the aerodynamic and aeroacoustic performance of the tunnel in its original configuration, treatment of the tunnel circuit with validation of in-flow noise reduction, wind tunnel tests to examine the effect of the test section acoustic treatment, and measurements of the aerodynamic and aeroacoustic characteristics of a NACA 0012 airfoil model over a range of angles of attack and Reynolds numbers. These measurements show that acoustically treating the walls of the circuit both upstream and downstream of the test section, as well as the fan, result in an overall reduction of 5 dB depending on frequency, of the in-flow noise level. These measurements also show that the complete system provides a reduction of between 15 to 20dB depending on frequency, in the in-flow background noise level. Measurements taken both within the test section and in the adjacent chambers also show that large Kevlar windows can be used to quietly and stably contain the flow, eliminating the need for an open-jet and jet catcher system, as well as overall noise levels competitive with many other facilities. Measurements on several airfoils at various angles of attack and Reynolds number show that the interference correction for the fully anechoic configuration is approximately -22% for model with a chord length equal to half the test section height. Aerodynamic measurements with the NACA 0012 airfoil show its lift, drag and boundary layer characteristics at high Reynolds numbers are consistent with theoretical expectations. Measurements of the window deflection as well as examination of flow transpiration through the Kevlar windows were accomplished, both with and without the NACA 0012 model. These measurements, along with the interference correction data, confirm that the Kevlar windows are a stable flow boundary. / Master of Science

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LD2668 .T4 1941 C47 / Master of Science

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Thesis (MComm (Economics)--Nelson Mandela Metropolitan University, 2011. / ENGLISH ABSTRACT: Renewable energy technology has received much attention over recent years. The depletion of known fossil fuel reserves and the volatility of international fuel prices require that society looks beyond the current coal-dominated electricity generation methods. Wind energy is an internationally well-established technology with large markets in major countries around the world, such as the USA and Germany. South Africa has the potential to generate large amounts of electricity from the wind because of the strength of the country’s wind resource. The long coast line and open areas are ideal for the exploitation of wind energy. / Sponsored by the Centre for Renewable and Sustainable Energy Studies

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

The interest in renewable energy has grown in recent decades because of environmental effects of fossil fuels and technological advances that have made some renewable energy technologies competitive with conventional gas fired power plants. Wind energy is playing a major role in increasing renewable energy’s share of electricity production worldwide. The global installed capacity of wind power has grown at a rate of more than 20% each year since the year 2000 (WWEA, 2009). Currently, the Mexican electricity sector is comprised of fossil fuel fired power plants. However, Mexico has a large endowment of renewable energy resources that can be harnessed to generate electricity. For example, the Comisión Reguladora de Energía estimates that Oaxaca´s wind power potential is about 10,000 MW (CRE, 2006). Studies have shown that Baja California´s wind power potential is also about 10,000 MW (KEMA, 2008). This thesis focuses on wind energy because it is expected to grow at the fastest rate during the next decade in Mexico relative to other renewable energy sources (Sener, 2008). Mexico’s installed wind power capacity is 202.5 MW. This capacity will increase by 456 MW by the end of 2010. Another 2,123 MW will be added during the period 2010-2012 (AMDEE, 2006). This research investigates various aspects of the wind farm development process in Mexico. The initial chapters describe the electricity sector and its participants. Subsequent chapters describe the regulatory framework and the mechanisms used by private investors to finance renewable energy projects. The final chapters describe the economic aspects of wind energy projects using a conventional discounted cash flow model. Statistical simulation is used to estimate capacity factors, and design of experiments is used to statistically analyze performance under different scenarios. / text

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