Investigation on Simultaneous Flow under a Sluice Gate and over a Trapezoidal Weir in a Circular Channel

Sharp crested weirs and sluice gates, because of their ease of making, water surface control potential and flow rate capabilities measuring have been broadly studied. Since the nature of flow on the weirs is highly complicated, mostly the driven equations are taken in to account a series of simplified hypothesis that are bases of empirical experiments. On the other hand most of the weirs cause a relatively calm zone of water on their upstream, which is a place of waste material and sediments to precipitate that is the disadvantage of the device. With gradual storage of sediments, the condition of flow changed and driven equations will lose their precision. In this case composition of weir and gate can be a useful solution for passage of floating materials over the weir and transmission of sediment materials from the lower part of the gate. In this study, hydraulic characteristics of the 18 combined model of trapezoidal weir-gate in the tree groups with three different opening gates at the end of an open channel with a circular cross section were studied. Using dimensional analysis, analytical solutions and statistical analysis, an equation for combined discharge by combined model of weir-gate was introduced and was evaluated by experimental data. The Results showed that the obtained discharge coefficient have a good agreement with experimental data.