抄録
Reviewing and analyzing the field test results carried out in 65 hydroelectric power stations in Japan, low head power station tends to have low velocity of wave propagation and it exceeds 1,000 m/s in power station of more than 100 m of net head. This is influenced by slight volume of air in the river flow because bubbly flow continues under low head, namely,low pressure. On the other hand,increase of pressure reduces the void fraction, that is no influence by the air, thus the wave propagation velocity is defined by only the rigidity of penstock. The wave propagation velocity for low head power station exceeds l,000 m/s in case means for vortex elimination is provided at the intake.
