Tomographic reconstruction of shock layer flows

Abstract

The tomographic reconstruction of hypersonic flows faces two challenges. Firstly, techniques used in the past, such as the Direct Fourier Method (DFM) or various backprojection techniques, have only been able to reconstruct areas of the flow which are upstream of any opaque objects, such as a model. Secondly, shock waves create sharp discontinuities in flow properties, which can be difficult to reconstruct both in position and in magnitude. ¶ This thesis will present a reconstruction method, utilising geometric ray-tracing and a sparse matrix iterative solver, which is capable of overcoming both of these challenges. It will be shown, through testing with phantom objects described in imaging and tomographic literature, that the results are comparable to those produced by the DFM technique. Finally, the method will be used to reconstruct three dimensional density fields from interferometric shock tunnel images, with good resolution.