Analysis on Separated Regions in Internal Flows Through Particle Image Velocimetry
Abstract
For internal flows, the detachment of the boundary layer is a major contributor to pressure loss. To improve efficiency, it is essential to characterize these regions to understand the location and magnitude. Particle Image Velocimetry (PIV) is applied to provide time-resolved measurements to achieve accurate results without perturbing the flow. This thesis covers the methodology for creating an adaptable optical measurement technique in a high frequency study of separated regions in transonic internal flows. Focus on the optimization of the laser optical array and image acquisition system yield improved Dynamic Spatial Range (DSR) and Dynamic Velocity Range (DVR). Further analysis is provided on the flow dynamics of the seed particle, with local seeding solutions provided for improved seeding density in high-speed flows for various geometries. Light scattering efficiency of the particle is also analyzed to completely define the desired particle size. Two pulse-burst Nd:YAG lasers and two high speed cameras are used in this study to achieve a frame straddling technique necessary to resolve high frequency flows. Comparison of the recording media to the DSR highlights performance costs and benefits between the two cameras. Uncertainty measurements are determined from the calculated setup and compared to correlation statistics-based uncertainty quantifications. Image processing and cross-correlation software are used to provide analysis on the flow characteristics for two separate studies with comparison to Computational Fluid Dynamic predictions.
Degree
M.Sc.
Advisors
Paniagua, Purdue University.
Subject Area
Design|Optics|Fluid mechanics|Information science|Mechanics|Thermodynamics
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