Experimental researches of hydraulic vacuum breakdown devices of siphon outlets of pumping stations

The paper presents the results of experimental researches of siphon outlets, which are used at large machine canals. It has been justified that siphon water outlets of the pumping stations operate in different conditions that siphon spillways at hydroelectric power plants and the mode of their operation have a significant impact on the operation of the pump. In terms proposed by us, the siphon has a constant width, equal to the diameter of the pipeline. The siphon length is reduced by 4.5 m. The height of the ridge is reduced so that the crosssectional area remains equal to cross – sectional area of the pipeline. The descending brunch is made with the same slope m= 1.6, the cone angle of the diffuser is a= -6°. The bottom of the outlet section of the siphon is raised by 2.5 m against the previous mark, the ceiling is deepened below the minimum water level by 1.0 m., and then smoothly turns up and out for 0,5m below the minimum headwater level of the upstream. The proposed version of the siphon when testing on the model was fully included at the maximum flow rate Q=18 m3/s. at a water temperature of 22°C