A combination of a stilling baffle and the inlet nozzle to promote smooth flow conditions in the channel.The flow over the weir apparatus includes the following elements that are used in conjunction with the flow channel in the molded bench top of the hydraulics bench (Figure 9.1). F1-13 rectangular and triangular weirs.The following equipment is required to perform the flow over weirs experiment: The general features of the flow can be determined by direct observation. The coefficients of discharge are determined by measuring the height of the water surface above the notch base and the corresponding flow rate. The objectives of this experiment are to:Ī) determine the characteristics of flow over a rectangular and a triangular weir, andī) determine the value of the discharge coefficient for both notches. Weirs are also built to raise the water level in a channel to divert the flow to irrigation systems that are located at higher elevations. Since there is a unique relationship between the critical depth and discharge, a weir can be designed as a flow-measuring device. Installing a weir in an open channel system causes critical depth to form over the weir. Weirs are commonly used to measure or regulate flow in rivers, streams, irrigation canals, etc. A coefficient of discharge needs to be determined experimentally for each weir to account for errors in estimating the flow rate that is due to these assumptions. The relationship between the flow rate and water depth above the weir can be derived by applying the Bernoulli’s equation and by making some assumptions with regard to head loss and pressure distribution of the flow passing over the weir. Sharp-crested weirs, commonly referred to as notches, are manufactured from sharp-edged thin plates. Weirs can be broad-crested, short-crested, or sharp-crested. Several types of weirs are designed for application in natural channels and laboratory flumes. IntroductionĪ weir is a barrier across the width of a river or stream that alters the characteristics of the flow and usually results in a change in the height of the water level.
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