Abstract:
This thesis is concerned with non-invasive ultrasonic flow measurement, using
the transit time principle.
The errors associated with the transit-time flowmeter are investigated and a
design of flowmeter is suggested. A theoretical and experimental study of the
transmission of sound through pipe walls is carried out where it is shown that
advantage can be taken of the excitation of Lamb modes. A design of transducer
arrangement is made from the results of the work.
A solution to the difficult problem of measuring very small times is provided in
the form of a novel vernier timing system. The benefits and disadvantages of
this timing system are discussed along with the design aspects of other
electronic circuits required in the construction of the flowmeter. The
flawmeter has been built and tested in the laboratory and is shown to be highly
repeatable and accurate. The results of testing the flowmeter compare
favourably with tests conducted on a commercial instrument.
Improvements to the design and construction and suggestions for further work are
given.