Design and Performance of A Pump-Turbine for Tidal Power

Search is continuing for alternative sources of energy. While using the gift of nature for developing energy, its balance must not be disturbed This would require to avoid pollution and hazardous effects. Tidal energy being perennial, non-pollutant and free from hazardous effects, offers a good scope. However, the head of water available will be small. Further the cost per installed kW will not be small. By resorting to pumping between two possible turbininq operations in the system, by designing a single machine with fixed blade setting for all the four modes of operation the system can be made economical.

This paper deals with the design of such an axial flow pump turbine to have approximately the same high efficiency in all the four modes of operation. Method of choice of camber and profile of the blade, design of the pitch to chord ratio of the profiles, stagger angle are described. Based on the requirements of kinematics and energy transfer, choice of an ‘S’ shaped camber and suitable direction of rotation have been made. For comparison purpose two more turbine runners were designed. The paper presents performance representation of 1100 experiments in a dimensionless manner. Cam curves have been evolved for performance representation. A comparison of the performance of the 3 possible axial flow pump turbine has been presented. In addition, the extrapolated results for the data of Gulf of Cambay has been compared with the one of the two tidal power plants of the world. The hydraulic design of a model pump turbine and its performance for a Tidal Power Plant at Gulf. of Cambay has been presented in this paper.