Doctor of Philosophy / Filtered Rayleigh scattering (FRS) is a laser-based measurement technique that makes use of the scattering of light off particles that are much smaller than the wavelength of light that hits them (i.e., Rayleigh scattering of air molecules). The scattered laser light is altered after encountering particles in predictable ways that can be related to changes in velocity, temperature, and density. However, other sources of scattered light interfere with the pure Rayleigh scattering signal such as Mie and background scattering. Mie scattering is the scattering of light off particles that are much bigger than the wavelength of light that hits them (i.e., dust particles suspended in air). Background scattering is the laser light scattered off physical objects that reflect back into the region of interest. The different types of scattering are accounted for with intensive modeling and iterative fitting schemes where the error between simulated data and experimental data is minimized. This fit allows for velocity, temperature, and density information to be extracted from the measured scattered light. This iterative scheme is then applied to experimental measurements on the ground with mini turbojet engines as well as full-scale turbofan engines. A data grouping technique is derived such that the total measured force using FRS can be divided into individual contributions from different parts of the engine. These developed techniques have laid the foundation for future in-flight measurements of engine forces.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/115078 |
| Date | 16 May 2023 |
| Creators | Powers, Sean William |
| Contributors | Aerospace and Ocean Engineering, Lowe, K. Todd, Schetz, Joseph A., Kapania, Rakesh K., Young, Gregory |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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