Engineering and Physical Science Research Council (EPSRC) / This thesis describes the development of the two-frequency Planar Doppler Velocimetry
(2n-PDV) flow measurement technique. This is modification of the Planar Doppler
Velocimetry (PDV) technique that allows the measurement of up to three components
of the flow velocity across a plane defined by a laser light sheet. The 2n-PDV technique
reduces the number of components required to a single CCD camera and iodine cell
from the two CCDs in conventional PDV. This removes the error sources associated
with the misalignment of the two camera images and polarisation effects due to the
beam splitters used in conventional PDV. The construction of a single velocity
component 2n-PDV system is described and measurements made on the velocity field
of a rotating disc and an axisymmetric air jet. The system was then modified to make
3D velocity measurements using coherent imaging fibre bundles to port multiple views
to a single detector head. A method of approximately doubling the sensitivity of the
technique was demonstrated using the measurements made on the velocity field of the
rotating disc and was shown to reduce the error level in the final orthogonal velocity
components by ~40 to 50%. Error levels of between 1.5ms-1 and 3.1ms-1 depending
upon observation direction are demonstrated for a velocity field of ±34ms-1.
The factors that will influence the selection of a viewing configuration when making 3D
PDV measurements are then investigated with the aid of a computer model. The
influence of the observation direction, the magnitude of the flow velocity, and the
transformation to orthogonal velocity components are discussed. A new method using
additional data in this transformation is presented and experimental results calculated
using four-measured velocity components are compared to those found conventionally,
using only three components. The inclusion of additional data is shown to reduce the
final error levels by up to 25%.
| Identifer | oai:union.ndltd.org:CRANFIELD1/oai:dspace.lib.cranfield.ac.uk:1826/1496 |
| Date | January 2006 |
| Creators | Charrett, Thomas O. H. |
| Contributors | Tatam, Ralph P. |
| Publisher | Cranfield University |
| Source Sets | CRANFIELD1 |
| Language | English |
| Detected Language | English |
| Type | Thesis or dissertation, Doctoral, PhD |
| Format | 7966707 bytes, application/pdf |
| Rights | © Cranfield University, 2006. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder. |
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