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The influence of hull boundary layers on waterjet intake performance

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Roberts, JL (1998) The influence of hull boundary layers on waterjet intake performance. PhD thesis, University of Tasmania.

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Abstract

The influence of hull boundary layers on typical waterjet propulsion system intakes
used in the fast catamaran ferry industry has been experimentally and computationally
studied. Particular attention was paid to the effect of boundary layer thickness on flow
quality at the pump impeller face.
A scale waterjet intake model mounted on the side wall of a wind tunnel enabled
performance to be determined experimentally. Surface mini-tufts, ingestion streamtube
determination, skin friction measurements and velocity and thermal anemometry
traverses were used to detail the flow. The most significant observation was the presence
of a separation zone on the intake roof. Two complete sets of results were obtained: one
with the wind tunnel's naturally thin boundary layer and another with an artificially
thickened boundary layer. The latter showed more extensive flow separation.
Computational work was conducted using the commercial finite element package
FIDAP. Grid independence required a surprisingly large number of nodes (approximately
300,000). However, good agreement with experimental results was obtained
with about 120,000 nodes.
Waterjet intakes installed on fast catamaran ferries ingest thick hull boundary layers
(hull boundary layer thickness is comparable with the intake diameter). Both experimental
and computational results show that a thick hull boundary layer adversely
effects the performance of such intakes. Therefore, inclusion of thick hull boundary layers
in the modelling/ designing of waterjet systems is essential for realistic performance
predictions.
The intake performance under manoeuvring conditions (zero vessel speed) was also
studied both experimentally and computationally. It was found that cut-water flow
separation choked the inlet and severely limited the available manoeuvring thrust.
Computational results for an increased cut-water radius indicated that substantial improvement
is possible with no detrimental effect on cruise performance.

Item Type: Thesis (PhD)
Copyright Holders: The Author
Copyright Information:

Copyright 1998 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Studies the influence of hull boundary layers on typical waterjet propulsion system intakes used in the fast catamaran ferry industry. Examines especially the effect of boundary layer thickness on flow quality at the pump impeller face. Thesis (Ph.D.)--University of Tasmania, 1998. Includes bibliographical references. Studies the influence of hull boundary layers on typical waterjet propulsion system intakes used in the fast catamaran ferry industry. Examines especially the effect of boundary layer thickness on flow quality at the pump impeller face

Date Deposited: 03 Feb 2015 03:17
Last Modified: 11 Mar 2016 05:55
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