Conference article

This paper provides an overview of different types of surge tanks used in hydropower systems. The water mass oscillation inside the simple, sharp orifice type, throttle valve, and air-cushion surge tanks are studied. It is found that the diameter of the sharp orifice and the throat plays an important role in obstructing water mass flowing inside the surge tank which consequences to reduce the effect of water hammer over times in the pressure tunnels. Sharp orifice type surge tanks are more efficient to reduce the allowed maximum height of surge tank for avoiding water spilling out of the surge tank during the total load rejection from the prime movers. However, throttle valve surge tanks are more efficient for decaying of pressure surges sooner. It is also found that the difference-amplitude of water mass oscillation inside the air-cushion surge tank is insignificant. Conclusions are drawn based on the case study of Trollheim and Torpa hydroelectric plants in Norway.

water mass oscillation, surge tanks throttling, sharp orifice type surge tank, air-cushion surge tank, throttle valve surge tank, water hammer