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.
Numerical Simulation on the Performance Improvement of a Lateral Intake Using Submerged Vanes
Lateral intake is a hydraulic structure which is broadly used for purposes such as agricultural consumption or urban water supply. To improve the efficiency of this structure, it is common to install a submerged vane near the entrance of this structure. Despite common applications of this structure, there is still a lack on correct description of flow structure near this structure and the variability of flow characteristics due to the geometrical characteristics such as lateral intake angle. In present study, we numerically investigate the role of submerged vane and lateral intake angle on flow structure using FLOW-3D simulation package. The results show that the lateral intake with 45° angle has the highest efficiency which can transport the highest amount of water together with lowest amount of sediments to the lateral intake. Moreover, it is also found that formation of a circulation zone between submerged vane and main channel lateral wall causes a high amount water to enter to the lateral intake with the lowest amount of sediment. Finally, simulations of flow in the presence of two submerged vanes show that two submerged vanes installed in a straight line and in a parallel configuration have higher efficiency in conveying water to lateral intake with low amount of sediment.
Reduction of gas flow nonuniformity in gas turbine engines by means of gas-dynamic methods
Gas flow nonuniformity is one of the main sources of rotor blade vibrations in the gas turbine engines. Usually, the flow circumferential nonuniformity occurs near the annular frames, located in the flow channel of the engine. This leads to the increased dynamic stresses in blades and as a consequence to the blade damage. The goal of the research was to find an acceptable method of reducing the level of gas flow nonuniformity as the source of dynamic stresses in the rotor blades. Two different methods were investigated during this research. Thus, this study gives the ideas about methods of improving the flow structure in gas turbine engine. On the basis of existing conditions (under development or existing engine) it allows the selection of the most suitable method for reducing gas flow nonuniformity.