Most of diversion tunnels in our country have the cross section of upper semi circle and lower square so that when the diversion tunnel is rebuild into a gyrating current flood releasing tunnel, its cross section should be changed into a circle section, which results in increasing greatly the engineering quantities in the second stage and is non economical.

Type selection of gyrating flow spillway tunnel in the right bank of the Gongboxia Hydropower Station;

Model similarity laws of gas-liquid mixed flow in horizontal swirling flow tunnels with vertical shaft