Evaluation of Unsteady Open Channel Flow Characteristics over Crump Weir

Sani Yakubu Khalifa, Abdullahi Umar

Abstract


A crump weir is commonly used to measure discharge in open flow channels. The laboratory test was conducted on six crump weir models of different apex angles 80o, 90o 100o, 110o 120o and 130°. Also by decreasing upstream angles to have the following values 85o, 70o, 55o, 40o, 25o and 10o. The increasing values of the downstream angles are 15o, 20o, 25o, 30o, 35o and 40o respectively to obtain the sum angle of triangle to be 180o. Plywood of thickness 22mm was used for fabricating the main body of the crump weir. This study comprises of laboratory work of physical model of crump weir based on unsteady open channel flow. It is therefore, concluded that, the weir model equation developed by linear combination method can suitably be used to compute discharge over the crump weir models with high precision and accuracy than the normal V-notch models. The larger the apex angle of the crump weir the more accurate will be in discharge estimation. From the result obtained model 6 is the most efficient crump weir having the least Cd of 1.15042 and least percentage error of 13.07552. And has best performance based on dependence of Qo on ho with 98.4%. Model 6 has apex angle of 130oupstream angle of 10oand the downstream angle of 40o.



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