Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.
This paper presents a theoretical model for
the prediction of the incipient of cavitation in
centrifugal pumps. The model includes the
physical fluid parameters and the real working
phenomena at off-design condition. The
parameters considered in the model were flow
rate ratio, pump rational speed, water
temperature, thermodynamic properties of
water, nuclei and gas content, relative velocity
and incidence angle. The thermodynamic effect
had a more complex expression compared with
other parameters. The present model has been
tested against extensive earlier published
experimental results in centrifugal pumps at
wide operating conditions. The comparison of
the predicted net positive suction head at
inception with the published data showed a
good agreement was achieved. This agreement
means that the roles played by operating
parameters, off-design phenomena and
thermodynamic properties of water are
consistent with the present model. The results
obtained from the present model make it
possible to explain why there is a difference
between the real net positive suction head
values and the theoretical ones in the previous
published models. Therefore, the present model
could help the pump user and designer to
estimate the incipient net positive suction head
at various conditions.
