Abstract:

Surge tank is a structure crucial to the stability of governing system and regulation quality. Thomas critical stable section area is a significant design criteria, but it neglects the effect of water interia in surge tank. This inertia could affect stable section area and governing quality if a surge tank has a long lateral pipe connecting to the intake tunnel, such as in a pumped storage station or high water head hydropower station. By theoretical analysis, numerical computation and engineering example in this paper, it is proved that the water inertia in a surge tank with a long lateral pipe helps to decrease the stable section area and improve regulation quality in small fluctuations and that neglect of water inertia in design is safer.