Variations of Flow Separation Zone at Lateral Intakes Entrance Using Submerged Vanes

Flow Separation in the upstream of the intake channel is a problem which produces an eddy flow at the intake entrance. It reduces the intake efficiency and the effective width of flow in intake and increases the sediment deposition in the intake entrance. Therefore, it is essential to identify the dimensions of the flow separation zone. Installation of submerged vanes in intake entrance is a method which has been applied to reduce the size of flow separation zone. In this research, the effects of submerged vanes on the dimensions of flow separation zone were investigated using five models of submerged vanes with different arrangement in four discharges of 15, 20, 25 and 30 Ls-1 in the main channel entrance. The Piney arrangement of submerged vanes was selected as the best model that reduced the size of flow separation zone and established a proper flow profile in the main channel and intake entrance. Comparing with the pilot model tests, this model reduced the length and width of flow separation zone 36.34% , 32.53% , 34.37% , 30.72% and 27.46% , 31% , 31.33 % ,30% at four different discharges of 15, 20, 25 and 30 Ls-1, respectively. Results showed that the ratio of width to length of separation zone (shape index of zone) was between two values 0.2 and 0.28 in the all models.