Bend Effect of Upper Bend Sections in Headrace and Tailrace Conduits of Xiangshuijian Pumped Storage Power Station

Hydraulic characteristics of the upper bend sections of headrace and tailrace conduits of Xiangshuijian Pumped Storage Power Station were studied. The bend effect was revealed: (1) The mean flow velocities of vertical lines at both sides in gate shafts were nearly equal to or larger than those of vertical line in the center, (2) The velocity distribution of vertical lines in the center was slightly distorted, (3) The piezometric head was not a constant along the circumference of cross section at the bend section. The influences of the bend effect on the velocity distribution can be reduced greatly, when the distance between the bend section and the gate shaft is about five times the conduit diameter, and those of the bend effect on the pressure distribution can be avoided when distance is about seven times the diameter. These research findings have been applied to the design of the project.