28-04-2014, 04:11 PM
Numerical Simulation of Flow through A Horizontal Split Case Pump
ABSTRACT
A split case pump of medium
size was analysed using Navier-Stokes
Solver for incompressible flow.
The geometry consisting of stationary
suction passage and delivery casing was
analysed together with rotating double
suction impeller.
The results are presented in the form of
vector plots and streak lines to visualize
quality of flow. The quantitative results
are presented in the form of total
pressure generated by impeller, losses
in suction passages, delivery casing and
that in rotating impeller.
Computational Grids:
The geometry of split case pump
consists of a common suction providing
flow to both the sides of impeller and the
impellers delivering to a common casing.
A typical double suction impeller is
shown in Fig. 1(a) and complete pump
geometry is shown in Fig. 2(a). The
geometry of suction passage and
delivery passage was prepared using
CFX- Build4 pre-processor.
As
geometry of suction passage was very
complex, mesh of this geometry was
generated in five blocks attached to each
other. Total suction passage consists of
56,000 nodes and is regular H type
meshes. The delivery passage was
prepared in three blocks viz. Volute
sections, cut water section and nozzle
section attached to make full delivery
passage. All the three blocks consisted
of 29,000 nodes in all.
CONCLUSION:
The results from numerical studies of the
flow through a horizontal split case pump
are presented here and compared with
the experimental results. The results
agree well with measurements at best
efficiency flow conditions. The entire
range of H-Q characteristics is predicted.
The predictions for efficiency at part flow
conditions is seen to be deviating from
the one actually measured. Some more
investigation needs to be done in this
direction. Similar exercise is being
carried out for pumps with different
specific speeds. The losses in the
suction passage and in the delivery
passage can be taken as the guideline at
the design stage.