تاثير شيب وجه پايين دست و بالا دست سرريز مستطيلي لبه پهن بر شرايط جريان

Influence of Downstream and Upstream Face Slope of Broad Crested Rectangular Weirs on Flow Characteristics

The aim of this investigation is to study the flow characteristics over the broad crested rectangular weirs with sloped upstream and downstream faces. This paper reports the effects of upstream and downstream face slopes on discharge efficiency of weir and the velocity profiles .The results showed that the critical flow section formed over the weir crest and was independent from flow discharge. As the downstream face slope was decreased the curvature of streamlines at downstream edge of the weir became much smoother. It was found that the modular limit of the sloped broad crested weir with downstream face slope of 10°, relative to standard broad crested weir, was increased from 69% to 96%.The results revealed that the discharge coefficient does not change with downstream slope. However, the increase in upstream face slope increases the discharge coefficient relative to standard rectangular broad crested weir. It was found that the discharge coefficient of sloped broad crested weir with upstream face slope of 10° was increased about 22% larger than the standard broad crested weir. By decreasing the upstream face slope, the uprising of the eddy currents at the junction of sloped and horizontal faces was found to be decreased.