Calculation of capacity of spillway № 2 Boguchanskoye HPP with free water overflow

The article considers a variant with the operation of spillway No. 2 of the Boguchanskaya HPP as the main spillway structure for the period of temporary operation of the hydroelectric complex. In the process of developing options for skipping construction costs, a calculation was made of the throughput with a free overflow through a flat threshold at the level of 167.0m at the FSL=175m and forcing the UVB to the level of 185.0 m with the damping of the flow energy in the water well. The task of the calculations is to obtain the discharge characteristics of the considered spillway option with the calculated flood hydrograph with a probability of 0.2%. At the same time, based on the throughput capacity of the spillway No. 1, the dependence of the turbine flow rate and the water depth in the downstream, as well as the transformation of the flood of a given probability, the estimated flow rate is 5500 m3/s, the maximum head H=18 m (determining) at a minimum threshold level of 167.0 m. Weir refers to weirs with a wide threshold. The throughput capacity of the spillway No. 2, operating in the free overflow mode, was determined. The change in the lateral compression coefficient depending on the head for the middle and outer working spans is considered. The outlines of free-falling jets behind the culverts operating in the free overflow mode are obtained, which makes it possible to refine the outlines of the side walls of the spillway.