Year: 1995
Type: dissertation
Abstract: Particle Image Velocity (PIV) is now a well established, non-intrusive technique for\nthe two dimensional measurement of fluid velocity from a single plane of interest\nwithin a fluid flow. This thesis presents new work into the application of the double\npulsed PIV technique to highspeed flows. The areas of work can be split into three\nmajor areas.\nThe first area of work involved a comprehensive study into data reduction using\nautocorrelation. Results from the study allowed the development of an optimisation\nmethod which provides a consistent basis for experimental design. Further work\nvalidated this method by comparing equivalent results from sets of PIV transparencies\nprocessed using a system developed from commercially available image processing\nequipment.\nThe second area of work involved supersonic flow studies of a de Laval expansion\nnozzle. PIV results were recorded from both inside and outside the nozzle. Inside the\nnozzle the PIV results resolved a normal shock and allowed comparisons with a 1D\ntheoretical model, a CFD prediction and Schlieren photographs. Outside the nozzle the\nPIV data permitted overexpanded jet shock cell structures to be resolved and\ncompared to a shock cell model.\nThe final area of work involved development of an image labelling system for high\nspeed flows by changing the transfer characteristics of the recording optics between\nexposures. A general theory of this technique was developed and a system designed\nand tested which can be applied to flows of arbitrarily high speed.
Author: Nicholas J. Lawson
Language: English
Subfield: Computational Mechanics
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W782473360