S.M. Sajadi; M. Shafai Bejestan; M. Bina
Abstract
Abstract
Settling basins are essential hydraulic structures which have to be designed and constructed at all river water intakes to remove most of suspended sediments which enters the intake by flowing water. There have been many techniques for designing these structures. To simplifying the design procedure, ...
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Abstract
Settling basins are essential hydraulic structures which have to be designed and constructed at all river water intakes to remove most of suspended sediments which enters the intake by flowing water. There have been many techniques for designing these structures. To simplifying the design procedure, some of these techniques have been applied many assumption and some others are so complicated which are difficult to apply or needs many data for design purpose. There are also some applicable methods which have been developed based on experimental or analytical procedures, but their results are not well known. Thus it is the purpose of this paper to compare these available methods. To do so extensive experimental tests were conducted in a flume of m using three different sediment concentrations under three Froude numbers. Field tests also were conducted in an irrigation rectangular concrete canal of 200 meter long, 1 meter wide and depth. Field tests also have been conducted under there different discharges different sediment concentration. Then the experimental data was used to determine the trap efficiency of settling basins by different methods. The predicted values were compared to the measurement values. The result indicate that the method of Swamee and Tyagi over predict the trap efficiency. This method was found to be more sensitive to the input data. Result obtained by the methods of Jin and Kaveshnikov were found to be more close to measure data than Raju and Garde methods. In this study a coefficient of Jin method in irrigation settling basin was determined for best estimating of.
Key words: Trap efficiency, Settling Basin, Suspended Sediment
A. Fathi; M. Bina; S.H. Musavi Jahromi
Abstract
Abstract
Stepped spillways are of most important hydraulic constructions to dissipation energy of water flow. These constructions are used in opening channel to transfer water from upper level to lower level. Because of considerable effect of steps on flow dissipation energy and also the resulted developments ...
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Abstract
Stepped spillways are of most important hydraulic constructions to dissipation energy of water flow. These constructions are used in opening channel to transfer water from upper level to lower level. Because of considerable effect of steps on flow dissipation energy and also the resulted developments in construction of roller competed concrete RCC, the mentioned constructions have drawn hydraulic engineers’ attention. In this research, physical models with three water chute slope in downstream face were used to survey natural air entrainment point in skimming flow .So three different slopes 1:1, 1:0/9, 1:0/7 (vertical & horizontal) were used in chute section after the standard crest parabola and before the steps start. Then the models were installed in hydraulic lab flume of Shahid Chamran University. The experiments were taken for 5 different flows per unit width (with amplitude 0.036 to 0.072 m2/s). The observations show that entrainment happens in water surface at certain distance from crest during the flow passes over the crest (Li). Results showed that crest downstream face geometry can cause change in flow hydraulics leading to change in boundary layer development because of different created (Li). Also it was seen that the 1:1 crest in comparison with other slopes, performs better hydraulically and creates a shorter entrainment point length (Li). In this paper the important results have been shown in the form of different tables and curves.
Key words: Stepped spillway, Dissipation energy, Air entrainment
