Plenoptic particle image velocimetry for quantifying flow field dynamics

Abstract

This thesis presents the development and validation of experimental and post-processing methodologies for the application of Plenoptic Particle Image Velocimetry (PPIV) to time-resolved, three-dimensional (3D), three-component (3C) flow measurements. The theoretical foundations of plenoptic imaging, particle image velocimetry cross-correlation algorithms, and relevant vortical flow structures are discussed. Three experimental configurations were investigated to evaluate and refine the PPIV system: a circular jet, a swept and tapered wing, and an unswept finite wing. Measurements of a circular jet at ReD ≈ 150 demonstrated the ability of PPIV to resolve key flow features, including centerline velocity decay, axial diffusion, vortex ring formation, and transition to turbulence. Additionally, time-resolved data enabled identification of unsteady flow features that do not appear in time-averaged data. Initial flow field measurements of both the swept, tapered wing, and unswept, finite wing highlighted challenges in resolving spanwise velocity components. Through variation of input parameters, data was quantitatively compared using signal-to-noise ratio analysis, vector invalidation rates, and phase-averaged convergence to understand trends and refine processing inputs. Final experiments conducted on the unswept, finite wing at Re ≈ 900, and α = 18◦ enabled identification and visualization of a tip vortex and vortex shedding in the wake. Overall, this study demonstrates that PPIV provides a cost-effective alternative and simplified experimental setup to traditional volumetric, time-resolved techniques such as Tomographic and Synthetic Aperture PIV. These findings support the continued development of PPIV as volumetric flow field measurement tool in fluid mechanics and aerodynamic flowcontrol applications.