May 2003 ISSUE TONGBAI Page 4/5 COMPACT HYDRO in ...

TONGBAI
4
TECHNOLOGY
Pump Turbine Model Development and Acceptance Tests
Successfully Completed
Having checked and verified the
hydraulic design and resulting
performance characteristics
and data by means of witnessed
model acceptance tests in the
laboratory of VA TECH HYDRO in
Zurich, in November 2002 the
customer officially accepted
and released the hydraulic profile
for the final design of the
prototype pump turbines.
The contract for the new pumped
storage power plant TONGBAI,
comprising the complete electromechanical
equipment for the 4 x
334 MVA units including the control
system, was awarded to VA TECH
HYDRO in January 2002 (for more
detailed information see HYDRO
NEWS 03/2002).
Based on the pre-design studies to
support the bid data, the final
hydraulic design and optimization
of the pump turbine components
were started early in 2002, using
three-dimensional (3D) numerical
tools for Computer Aided Design
(CAD) of spiral casing, stay vanes,
guide vanes, runner and draft tube.
For simulation of the flow pattern in
the stationary cascades during turbine
and pump mode, 3D Navier
Stokes computations were applied
to minimize hydraulic losses and to
optimize the profiles of stay vanes
and guide vanes. Special attention
was paid to the runner design to
achieve cavitation free operation
during normal pump operation. In
view of smooth operation and a low
level of pressure fluctuations, it was
important to obtain a good flow interaction
of the runner with the distributor
and the draft tube.
According to standard practice,
simultaneously the mechanical design
of the blade profiles was
The pump turbine model installed on the test rig in Zurich
checked to guarantee that the admissible
limits of stresses and deformations
were respected. This
also goes for the guide vane profile
and the location of its pivot, where
it was essential to get torque characteristics
with low maximum and
minimum values.
Early in 2002 also design and manufacturing
of a homologous model
pump turbine started, related to the
prototype machine by a scale factor
of 1:11.93, so that an outer model
runner diameter of 402.5 mm resulted.
First model test results were produced
in June, and after a rather
short period of runner fine-tuning,
the model was ready to start contractual
tests as per customer’s
technical specification. Early in
September the preliminary test report
was submitted which included