Technical Approach for HydroPowerKUNIO YASUDA*1

HISAYUYKI SAKA*1

Hydropower contributes to reducing emissions of carbon dioxide (CO2) to mitigate global warming compared to other electricpower generation methods because it is renewable energy and does not produce CO2 . In particular, pumped storage power plants canstore the nighttime surplus power generated by nuclear power plants and utilize it to respond to the daytime peak demand. Therefore,
with its usefulness in operation and effectiveness at mitigating the global warming, the importance of pumped storage power plants isattracting increasing attention and pump turbines for pumped storage power plants are required to improve performance.
runner with splitter blades where performance improvements
such as an increased efficiency at partial load, improved
cavitation characteristics and reduced pressure pulsation
have enabled to extend the operating range. Initially, therunner with splitter blades was applied to high head turbinesand pump turbines, and its application has been expanded
the medium head Francis turbines. Today, using the latest
CF D technolog y, MHI can produce high per formancerunners that have a wide operating range with high efficiency
at partial load and good cavitation characteristics which
are characteristics of runners with splitter blades.1 The
runner also allows the variable speed pump turbines inpumped storage power plants to extend their operating range
compared to conventional pump turbines.

1. Pump turbine configuration and technology
for high performance
Mitsubishi Heavy Industries, Ltd. (MHI) is developing
and improving the performance of a Francis turbine, which
is a typical turbine used in hydraulic power plants, by using
the latest computational fluid dynamics (CFD). To optimize
the total turbine performance, an entire flow analysis is used.
In this CFD analysis, an analysis is made on the entire water
passage components from inlet of spiral case to outlet ofdraft tube which enable to evaluate the total performance ofturbines by numerical simulation. As for the runner design,
MHI has established a new runner design method to adjust
the load distribution on the runner blades by controlling thesecondary flow on the blade surfaces to reduce losses.1 Afterverifying the accuracy of the results of CFD analysis forthese designs in comparison with the model test results, thedesign method has already been adopted in the design of the
prototype turbine and pump turbines.

3. Conclusion
Hydropower has been used to create hydroelectricity
for over 100 years. However, new technology is still being
developed as described in this paper, and the development of
new runners helps to generate more energy. In addition, theimproved convenience and benefits of hydropower promotes
total system optimization which enables nuclear and thermal
power plants to operate efficiently. This allows the power
generation system as a whole to contribute to reducing CO2 .
MHI will promote the development of turbines and pumpturbines aimed at improved efficiency and a wider operating
range to continue contributing to the mitigation of global
warming.

Fig. 1 Replacing runner
An example where a newly CFD designed
runner replaces the existing one.

Reference
1. Miyagawa, K. et al., Development of High Performance Hydraulic
Turbine Contributing to Solution of Global Warming Problem,
Mitsubishi Juko Giho Vol.41 No.3 (2004) p.166

2. Developing runner with splitter blades
A wide operating range in turbine operation from low tomaximum output and from low to high head is required dueto the demands of the system and changes in the water flow inrivers.
These needs prompted MHI to research and develop a newKunio Yasuda

Hisayuki Saka

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 45 No. 1 (Mar. 2008)*1 Takasago Machinery Works66