University of Duhok College of Engineering Department of Mechanic Title: Discharge over a Vee Notch Weir Name: Loran Experimental date: 2/15/2021 Submit date: 2/29/2021 List of content: 1. Introduction 2. Objective 3. Materials and Apparatus 4. Procedures 5. Calculations and Results 6. Reference 1. Introduction : A 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. Several types of weirs are designed for application in natural channels and laboratory flumes. Weirs can be broad-crested, short-crested, or sharp-crested. Sharp-crested weirs, commonly referred to as notches, are manufactured from sharp-edged thin plates. 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. 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. 2. Objective : The objectives of this experiment are to: a) determine the characteristics of flow over a rectangular and a triangular weir, and b) determine the value of the discharge coefficient for both notches. 3. Materials and Apparatus : 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 A combination of a stilling baffle and the inlet nozzle to promote smooth flow conditions in the channel. A vernier hook and point gauge, mounted on an instrument carrier, to allow measurement of the depth of flow above the base of the notch. The weir notches that are mounted in a carrier at the outlet end of the flow channel. 4. Procedures : This experiment will be performed by taking the following steps: Insert the stilling baffle into the slots in the sides of the channel of the hydraulic bench Insert the rectangular weir and fit it tightly using thump nuts Start the pump and open the water supply Adjust the water supply and make the water level become steady Take for every height a flow discharge Repeat the previous procedure for the vee notch also 5. Calculations and Results : Crest Level (mm) Gauge Volume Reading (Lt) (mm) Time (S) H (m) 𝟓 𝑯𝟐 𝑸𝒕𝒉 𝑸𝒂𝒄𝒕 𝟑 𝟑 (𝒎 /𝒔) Cd (𝒎 /𝒔) 141 54 25 26.75 0.087 0.661 141 57 25 28.46 0.084 0.66 141 61 25 32.42 0.080 0.676 141 76 25 54.47 0.065 0.67 141 94 15 65.2 0.047 0.75 141 105 5 43.49 0.036 0.756 6. Reference : https://www.academia.edu/13873138/Flow_over_a_rectangular_and_vee _notches https://uta.pressbooks.pub/appliedfluidmechanics/chapter/experiment-9/