In this thesis an investigation for the identification, measurement
and modelling of the gear pump performance under marginal suction
condition, created in the suction line and resulting in cavitation at
the suction port and cavitation erosion on the delivery side plate is
introduced. A new technique for the detection of cavitation in gear
pumps has been employed and proved to be more efficient and less
expensive than other techniques available. The experimental study has
been carried out by monitoring the pressure ripple at the pump inlet
and outlet, as well as investigating the pressure distribution around
the gear rotor under cavitating and non-cavitating conditions. It was
found that the gear pump cavitation appeared in three distinct stages,
these being cavitation-inception, discrete-cavitation and
continuous-cavitation. These stages of cavit tion were investigated by
means of pressure distribution around the gear rotor using a miniature
pressure transducer positioned at a gear fillet. The experimental
results demonstrate a drop in filling efficiency, of the tooth space
due to cavitation, which provides a further understanding of the pump
performance characteristics at different inlet conditions. An
expression for the definition of transient pressure in the tooth space
due to trapped volume has been derived for the first time and proved
to give a good correlation with published experimental work. A surface
analysis technique has been employed in this work to study the
behaviour of the material erosion due to cavitation bubble collapse,
using a 'Talysurf 41 instrumentation system, and the results obtained
are in good agreement with those published by NEL
