PhD Oral Exam - Farshad Rezaei, Mechanical Engineering

When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.

Abstract

The need for sustainable energy solutions is more pressing than ever, and wind energy presents a promising option. Among various wind turbine designs, the Vertical Axis Wind Turbine (VAWT) stands out due to its efficiency in low-wind conditions and its ability to capture wind from any direction. This study utilizes Computational Fluid Dynamics (CFD) to explore the potential benefits of installing VAWTs on roof-tops of buildings. By employing CFD simulations, we analyze the efficiency and performance improvements achievable through strategic placement of VAWTs in urban environments.

Placing VAWTs on building roof-tops is significant for harnessing local wind energy and reducing the costs and losses associated with power transmission. By integrating wind turbines directly into the building structure, energy can be generated on-site, thereby enhancing energy efficiency. Our findings indicate that a VAWT installed on a 30.48 m (100 ft) building roof-top can achieve up to a 36% increase in maximum power output. For taller buildings, this increase can reach up to 84%, demonstrating the substantial impact of building height on wind energy capture.

The study further investigates the placement of VAWTs at various positions on roof-tops and examines the effects of the Atmospheric Boundary Layer (ABL) on performance. Results reveal that the power coefficient (CP) of VAWTs can reach 0.487 in minimally obstructed coastal areas but decreases with increased terrain roughness. Additionally, positioning a VAWT on a dome structure, compared to a cubic building of equal height, results in a significant 50.7% increase in the maximum CP. This variation underscores the importance of building shape and placement in optimizing wind energy capture.

Establishing a human presence on Mars may be a possibility in the next few decades. In such a scenario, energy production is crucial. Domes are likely to be the preferred living structures on Mars, offering stability and protection against the planet's harsh conditions. Positioning VAWTs atop these domes can effectively capture Martian winds, providing a sustainable and reliable energy source for the inhabitants. Winglets on the VAWTs improve aerodynamic efficiency by mitigating tip vortices, leading to a CP increase of up to 35.8% at optimal Tip Speed Ratios (TSRs). Furthermore, placing the VAWT on a dome enhances performance by accelerating incoming flow and reducing vortex formation, achieving a CP increase of 53.9% at peak performance.

Placing VAWTs on roof-tops significantly boosts power extraction, with increases in energy output of up to 84% for taller buildings. The strategic positioning of VAWTs, particularly on domes and at various roof-top locations, proves essential for optimizing wind energy capture. The findings underscore the potential for VAWTs to enhance energy efficiency both in terrestrial and extraterrestrial environments, paving the way for more sustainable energy solutions.