Showing 3 results for Spatially Varied Flow
S. Kouchakzadeh,
Volume 6, Issue 3 (10-2002)
Abstract
Side channel spillways have a common usage in conveyance and distribution networks, high dams, water and wastewater treatment plants, and surface drainage networks. A side channel carries spatially varied flow with increasing discharge and their water surface profiles is a main feature in the design process. Usually, the bottom width of the channel is flared in the flow direction and an end sill is also installed at the downstream end to provide a control section and to generate an even water surface profile. In this study, the impact of installing an end sill on the flow characteristics in a non-prismatic side channel is presented. Six distinct longitudinal profiles were clearly observed in each run and the difference between the mid points of the maximum and the minimum profiles of each run was used to evaluate the sill effects on the water surface profile and the energy dissipation.
The results indicated that the maximum and the minimum differences are, respectively, equal to critical depth and half of it generated at the channel downstream end. Also, based on an envelope of the data, a method was proposed to determine the maximum potential impact of an end sill that might have on the flow depth, which could also be considered as a guideline in the design process.
E Izadi, M Heidar Pour, A Kabiri Samani,
Volume 12, Issue 46 (1-2009)
Abstract
In this study, the flow characteristics have been investigated by measuring separation zone, surface and velocity profiles over the circular crested side weirs. An equation was proposed for the length of the separation zone using dimensional, statistical and regression analysis. The dimensional analysis showed that the length of separation zone depends on the upstream to the downstream water depth over the side weir, channel width to the downstream water depth and the Froude number. Comparison of the longitudinal and sectional surface profiles showed that the surface profiles at the vicinity of the side weir are non-uniform, due to separation zone close to the side weir. Therefore, the suitable place for measuring the characteristics of flow is along the centre line of the channel. It was observed that the maximum velocity occurred below the surface water which might be due to the secondary flow around the side weir. By increasing the distance far enough from the side weir, the effects of secondary flow were minimized and the velocity profiles tended to be uniform.
T. Honar, S. Mazloom Shahraki,
Volume 18, Issue 69 (12-2014)
Abstract
Cylindrical and semi-cylindrical weirs are used in water distribution systems for flow measurement in open channels and for control of water surface. Review of literature shows that cylindrical and semi-cylindrical weirs are not widely used in practice. Because of their low construction cost and simplicity, an investigation was done to study cylindrical and semi-cylindrical weirs in terms of their hydraulic characteristics such as discharge coefficient, energy loss and flow depth over the spillway crest. The research was done for 128 models in the hydraulic laboratory of water engineering department, Shiraz University. According to the results, due to flow separation from body of the weirs, flow coefficient increases in the cylindrical and semi cylindrical weirs by 57%. It was found that discharge coefficient increases by increasing the total head of upstream. Therefore, construction of cylindrical and semi-cylindrical weirs and side weir is recommended due to reduction in weir length, increased hydraulic efficiency, and reduced administrative costs compared to other wide edge side weirs.
