MPhilThesis-1992-Poullikkas.pdf (4.28 MB)
Two phase flow and cavitation in centrifugal pump: a theoretical and experimental investigation
thesis
posted on 2013-01-03, 13:05 authored by Andreas PoullikkasExisting designs of centrifugal pumps can only handle very
modest amounts of gas before they deprime. A normal
centrifugal pump cannot usually handle any liquid having more
than 7-9 percent gas content (by volume). Even this small
percentage creates drop in head on the order of 20 percent as
compared with 100 percent liquid. Furthermore the cavitation
phenomenon
considered
is one of the most important problems
in designing and operating a centrifugal
pump.
Especially when the uprating of pumps and driving at higher
speeds to reduce size, its importance becomes greater. The
physical mechanism of both two phase flow and cavitation
remains to a great extend unexplained. In this investigation
an attempt has been made to study these phenomena. A control
volume method was employed to derive a mathematical model for
a centrifugal pump under two phase flow conditions. The model
combines the ideal (Eulers) two phase head of a centrifugal
pump with additional losses due to compressibility and
condensation of the gas phase. Systematic tests were carried
out on a centrifugal pump of conventional design in order to
established the causes of two phase head degradation and
support the derived mathematical model. The excellence of the
agreement obtained between the mathematical model and the
experimental results gives confidence that it will be possible
in the near future to predict the two phase head-capacity
curve for any centrifugal pump. High speed video observations
identified the basic mechanism leading to flow breakdown when
pumping two phase mixtures and
two phase flow and cavitation.
History
School
- Mechanical, Electrical and Manufacturing Engineering
Publisher
© Andreas PoullikkasPublication date
1992Notes
A Master's Thesis. Submitted in partial fulfilment of the requirements for the award of Master of Philosophy of Loughborough University.Language
- en