Flow assessment through imaging techniques : applications to wind augmentation and aortic dissection flow -

Abstract

Flow-Imaging techniques constitute an essential part in the field of experimental fluid dynamics due to their high-fidelity measurements of actual systems. Recent developments in these methods and their applications in the multiple aspects of aerodynamics, aeroacoustics, wind energy, and bio-inspired domains have led to numerous studies being performed and advancements being implemented. In this dissertation, established flow visualization methods Particle Image Velocimetry (PIV) and Laser-Induced Fluorescence (LIF) are employed to assess the fluid dynamics and flow structure of two selected applications, drawing from the wind energy and bio-inspired domains, in the aim of improving the understanding of the fundamental regimes governing them. In accordance, this thesis is composed of two parts presenting studies of each corresponding application. The first part handles the use of PIV to analyze the flow behavior and velocity augmentation inside several shroud geometries subject to free-stream conditions. To provide a reliable benchmark to flow augmentation coupled with the shrouding process and a data set for validation of CFD models, reduced-model geometries with different shroud variants are subjected to free-stream conditions inside a wind tunnel test section. PIV is then employed in order to measure the required velocity fields, allowing for extraction of the flow augmentation ratios and assessment of the shroud effect on the flow. The second part employs PIV and LIF in order to study the fluid dynamics inside an aortic dissection, a high-mortality cardiovascular disease. With the assistance of AUBMC radiologists, reduced aortic models with different disease configurations are placed in quasi-realistic conditions. PIV is then employed to generate a quantitative visualization of the flow dynamics, while LIF is used to extract specific flow patterns. LIF imaging, with its comparability with the CT-scanning machine used to diagnose dissections, provides radiologists with a reliable reference and helps to impr