A three dimensional
numerical analysis of turbulent flow in the two intakes of this smaller
hydroelectric plant was carried out.The configuration and coarse grid,
shown in the top Figures, included a complex geometry involving trash
racks, turbine sections, large curved sections and circular pipes
as well as complex flow conditions at the inlet entrance such as a
turning flow and separation. These flow conditions required the use
of the 3D
ASL-COCIRM in-house code to model the approach flow in
the forebay to provide the distribution of the velocity field at the
inlet boundaries of the CFD computational domain. The distribution
of the mean streamlines and velocity field at selected planes is shown
in the middle and bottom left figures. Large wakes are produced by
the top I-beams as the flow descends the intake. These wakes diffuse,
interact and merge by the slot location. The effect of the turbine
section on the flowfield is clearly noticeable. The flow slows down
over a large middle area when approaching the large turbine nose.
Large flow recirculations are present at the intake entrance of Unit
2, which contribute to the increase in head losses.
The CFD mean horizontal measured velocity profile displayed in the
last Figure showed a very good agreement with the ASFM data. Other
comparison of the local mean velocity components profiles collected
by the Nortek Doppler Velocimeter (NDV) showed an excellent agreement,
as well.
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