Abstract:
The
applications of ultrasonic imaging and signal processing in two-phase flow
measurement have been
investigated in this thesis. The scattering by single and many
scatterers was studied
experimentally and numerically. The statistical properties of the
scattered waves from
many scatterers were examined and the corresponding results are
presented. Ultrasonic transmission/reflection mode tomography was introduced. The
theories of reflection mode
computerised tomography were developed, by which
reflectivity functions and scattering amplitude functions can be reconstructed. Image
restoration and
interpretation methods are presented. Computer simulation of ultrasonic
measurements were carried out. A ultrasonic tomographic imaging system was
developed, in which fan-shaped sound beam insonification was employed. Static physical
models were used to simulate
two-phase flows. In order to speed up the data acquisition
of a
tomographic imaging system, the single receiver mode and multiple receiver mode
data
acquisition arrangements were studied by experiments. Experiments on imaging
small and
large objects were carried out. Several signal and image processing methods
were examined. A modified histogram equalisation algorithm was developed for
processing the resultant ultrasonic images. The experiment results show that the
proposed image reconstruction methods are satisfactory. Possible future developments
are
proposed.
