Abstract:

Discharge through a rotary flow spillway tunnel with blockage and its influencing factors were studied with model test and theoretical analysis. This discharge is closely related to the flow pattern in the tunnel: it is a weir flow when the tunnel inlet and shaft are not submerged, while an orifice flow when submerged. In the condition of submerged tunnel inlet, the discharge is influenced by both the vortex generator inlet and blockage orifice, and the flows at these two locations follow the law of pressurized orifice flow. At the generator inlet, the discharge coefficient depends on the energy loss upstream and the local pressure, and the latter is the main factor. At the blockage orifice, it depends not just on the energy loss upstream, but on the variations of flow swirling behaviors caused by the blocking device, such as relative cavity radius, rotary angle, and relative wall pressure. At the generator inlet, this coefficient is 0.4 at contraction ratio m=0.56 and in the range of 0.55~0.65 at m£0.18, while at blocking orifice, it is close to 0.5 at m=0.56 and in the range of 0.25~0.32 at m£0.18. An expression for calculation of the cross-sectional area of generator inlet has been derived.