Weir Flow&Flow Measurement in Pipe

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Open channel flow Abstract Open channel flow is defined as flow in any channel where the liquid flows with a free surface. Open channel flow is not under pressure; gravity is the only force that can cause flow in open channels and a progressive decline in water surface elevation always occurs as the flow moves downstream. This experiment uses sharp-crested thin plate weirs to measure the flow rate f water in an open channel. The aims to determine if weirs can be used to measure flow rate in an open channel to reasonable accuracies. Aim Use the sharp-crested thin plate weirs to measure the flow rate of water in an open channel. And also determine if weirs can be used to measure flow rate in an open channel to reasonable accuracies. Equipments Stop Watch; Scale; Rulers; Channel system with constant water flow supplying by pump; Sharp-crested Rectangular and Triangular (V-notch) weir Sharp-crested weirs are overflow structures whose length of crest on the direction of flow is equal to or less than two millimetres. The weir plate should be smooth and plane, especially in the upstream face, while the crest surface and the sides of the notch should have plane surfaces which make sharp 90-degree intersections with the upstream weir face. The downstream edge of the notch should be bevelled if the weir plater is thicker than two millimetres. Note: Make sure that the flow does not cling to the downstream face of the weir plate, after water has passed over the weir crest. Thus, an air pocket must be present below the nappe, as shown above. This is to ensure that pressure in the water in the nappe is approximately atmospheric and constant. Photos and Sketchs of the Equipments: Flow over a sharp-crested weir Geometry of a triangular (V-notch) weir Device use to contol the out flow Set up of the Rectangular

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