M. Karami Moghaddam, M. Shafai Bajestan, H. Sedghi,
Volume 15, Issue 57 (10-2011)
Abstract
In diversion flows, a portion of stream flow which enters the intake is diverted from upstream of the intake denoted by a surface and is called dividing stream surface (DSS). The amount of flow and sediment discharge entering the intake as well as design of submerged vanes to control sediment depends on determination of dividing stream width. In this study, the experimental tests were carried out at a 30 degree water intake from a trapezoidal section. Three components of velocity data were obtained for different flow conditions. Then numerical SSIIM2 model was calibrated and verified using tests data. More flow conditions such as the main channel with rectangular section were run using SSIIM2 model to get enough hydraulic data. From analysis of these datas it was found that the dividing stream width in different distances from the bed depends directly upon the diversion flow ratio. It was found that in comparison to the rectangular section, in trapezoidal cross section, the DSS dimensions are modified in such a way that its width is increases at the surface and reduced at the bed for the same flow conditions. Relations for predicting the dividing stream width and diversion flow ratio have been presented in this paper for intake from both rectangular and trapezoidal cross sections.
M. Halvaeifard, A. Masjedi,
Volume 20, Issue 78 (1-2017)
Abstract
One of the methods for sediment control in lateral intake can be application of submerged vanes in front of the inlet. The establishment of submerged vanes in flow path causes a flow diversion toward the inner arc. In this research, the performance of submerged vanes on sediment transport to the inlet at 180 degree of intake has been investigated. Several experiments were carried out in a laboratory channel made of Plexiglas at a 180-degree arc, under clear water condition. In this research a series of experiments were done by inserting several vanes made of Plexiglas in front of lateral intake. Experiments were done by using two rows of parallel vanes with variable angles at four different discharges under two conditions of with and without vanes. In each experiment, the main channel discharge and diversion channel discharge, sediment discharge through the diversion and transmission were measured. The results of research showed that the performance of the parallel submerged vanes in diverting the path of sediments depends on contacted vanes angle by water flow. Also, entering water rate is directly proportional with entering sediment rate and entering sediment rate are increased with the increase of entering water rate at all angles. Suitable performance in reducing the sediment transport to the inlet was observed at an angle of 15 degrees of vanes relative to the axis of water flow. In other words, by increasing the angle relative to the axis of flow, sediment transport to the inlet will be increased.
