جستجوی مقالات مرتبط با کلیدواژه « زاویه آبگیری » در نشریات گروه « عمران »

Lateral Intake which uses a pipe is a hydraulic structure that has been utilized in water intake from rivers and channels, especially in those situations in which the area topography doesn’t allow to build a lateral channel for water intake. This study deals with the numerical investigation of effective geometrical parameters on lateral intake efficiency with a pipe in a rectangular open channel by using Flow3D software. The parameters that studied, are including the direction of the pipe intake respect to the main channel, the position of the pipe intake entrance in the width of the main channel, the position of the pipe intake entrance in the water depth, the diameter of the pipe intake and the shape of the pipe intake entrance. The comparison of the diverted discharge results for different levels of the pipe intake indicated that if the water intake is placed at relative height level of 0.28 to 0.57 of the water depth, the diverted discharge would be more than others.  Furthermore, by comparing anti-sediment coefficient for different levels demonstrate that if the pipe intake locates near the surface of the flow, anti-sediment coefficient will have an acceptable value.

Secondary current in the river bend causes transportation of the river bed sediments towards the convex bank. Several parameters affect the rate of sediment diversion to the intake. In this research, the effects of intake angle on sediment rate were investigated in two extreme angles, 5 degrees (the gentle angle) and 90 degrees (the sharp angle), under various discharges and flow diversion rates. The results show that the outflow capacity of intake in 52-degree is higher than 90-degree about 21 percent for various discharges. Therefore, it is possible to decreases the width of intake mouth in 520 diversion angle proportionally. Comparison of the sediment diversion rates in two angles shows that, in case of intake with 90-degree diversions angle, up to 22 percent, less sediment diverts into intake mouth, compared with 52-degree diversion angle. At this angle because of the quick rotation of flow surface towards intake mouth, the angle between surface flow and bottom flow increases (about 90 degree), and the power of secondary flow, increases, and consequently decreases sediment entry into intake. Secondary flow power in intake mouth causes by secondary flow in the bend and diversions angle that is identified by Psec Index. By increasing the flow rate diversion in 900 diversions angle, the domain of flow diverted into the intake mouth expands more than the width of bend and approaches to the moving sediment bar in the inner part of the bend. This flow acts the same as flow in the outer bend of the river but with higher potential for sediment transportation progression. At the 52 degree angle, the flow rotates with a minimized angle by diverting a part of river flow into the outer bend. Therefore, at the lower angle in flow diversion and intake alignment, the power of secondary flow becomes weaker than the 90-degree angle. This results in lower rate of up to 22 percent more sediment diversion into the intake compared with 90-degree diversion angle.