Sediment Entry Investigation at the 30 Degree Water Intake Installed at a Trapezoidal Channel
2 Abstract: A major problem which most of lateral intakes are faced with is sedimentation and sediment delivery. This process causes many problems such as reduction flow discharge capacity in irrigation canals as well as threatening of blockage of water during low water flow. Therefore it is the main goal of engineer to design an intake with higher flow discharge and low sediment delivery. Since most of lateral intakes are installed at trapezoidal which has not received the same attention as intake from rectangular canals, it is the main goal of this study to investigate sediment delivery to an intake from trapezoidal canal. In this study, sediment tests carried out for different hydraulic conditions at a 30 degree water intake installed at main channel with inclined bank. From analysis of these it was found that the flow patterns at the upstream of the intake has been modified in such a way that more water from surface layers are diverted. Therefore less suspended sediment enters the intake. Also it was found that in all tests the amount of sediment enters the intake reaches its minimum value at Froude Number between o.35 to o.4. In low flow depth because of the effect of bed roughness over strength of secondary current, the suspended sediment enters the intake is lower compare to the higher flow depth for the same conditions.
Effect of vortex formation on sediment transport at dual pipe intakes
Vortex formation and subsequent sediment transport into the intake due to sea water withdrawal is one of the problems in coastal engineering. The effect of vortex formation on rate of sediment transport at coastal dual pipe intakes was investigated using a scaled physical model. Experiments were performed on dual pipe intakes at three common intake withdrawal directions (vertical, horizontal and with angle of 45°). In each experiment, the class of vortex with respect to its strength was determined. Particle tracking velocimetry (PTV) was employed to measure tangential velocity of vortices. Results indicated that the rate of sediment transport was considerably affected by the strength of formed vortices. The rate of transported sediment was increased by increasing the strength of formed vortex. Moreover, amount of sediment transport was affected by angle of pipe intakes. It could be concluded that the minimum and maximum rates of sediment transport occur for inclined and horizontal intakes, respectively.
Ignition and burning rates of segregated waste combustion in packed beds.
Recent developments in national recycling and re-use programmes for municipal waste have led to segregation of an increasing proportion of waste to enhance material recovery. Several of the segregated streams contain materials that can not viably be re-used or recycled but can be used for energy recovery. In this study, the combustion of cardboard and waste wood was investigated in a small-scale packed bed reactor in order to provide fundamental data for the design/operation of moving bed furnaces. Key parameters of combustion including the ignition and burning rates were evaluated for various air flowrates and compared to the modelling results. Two successive stages of combustion were identified for both samples: the propagation of ignition front into the bed and combustion of the fuel above the ignition front. The burning rate of cardboard reached a peak of about 300 kg/m(2)h at the air flowrate of 936 kg/m(2)h and decreased at higher air flowrates. For waste wood, both the ignition and burning rates increased in the tested range of the air flowrate up to 702 kg/m(2)h, of which the values were very close to those for the cardboard. The model prediction was in good agreement with the test results for waste wood. However, the burning rate for cardboard was under-predicted due to strongly irregular shapes of the fuel.