Investigation of submerged vanes arrangements effect on dimensions of flow separation zone at lateral intake entrance

Flow Separation in the upstream of the intake channel is a critical issue causing eddy flow into the intake entrance. It can both reduces intake efficiency and the effective width of flow and increases sediment deposition in the intake entrance. Therefore, it is essential to identify dimensions of flow separation zone. Installation of submerged vanes in intake entrance is a method which is usually applied to reduce the size of flow separation zone. In this study the dimensions of flow separation zone were measured in presence of submerged vanes with five arrangements including parallel, stagger, compound, piney and butterflies (piney and butterflies models were investigated for the first time) by four discharges of 15, 20, 25 and 30 L/s in main channel entrance. Multivariate regression equations were extracted for investigated flow separation zone using SPSS software. R2 of these equations changes from 0.87 to 0.96, which statistically, can be considered as valid equations in hydraulic flow studies at lateral intake entrance. These results are also comparable with other studies which all of them show a reducing of the size of flow separation zone with increasing ratio of lateral intake discharge. Piney submerged vanes were selected as the best model that reduced the size of flow separation zone and made proper flow profile in main channel and intake entrance. Comparing with 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% respectively at four different discharges of 15, 20, 25 and 30 L/s.

Keywords:

lateral intake , flow separation zone , submerged vanes , piney model , multivariate regression