Evaluate the discharge cofficient of semi circular weir (notch)‎

الملخص EN

The weir applications in the measurement of discharge large and small channels are open in the field or the laboratory, and in general can be defined weir as a handicap regularly happen flow from it.

More weirs widespread and commonly used is the weirs sharp with a notch of rectangular and triangular, which is often where the coefficient of discharge cd starts from 0.55 for the rectangular notch and 0.59 for the triangular notch, but these transactions are affected by viscosity and surface tension, roughness of the plate and weir.

In this research was the work of models with semi-circular notch, meaning it took half a circular notch in three different models diameters (6cm, 8cm, 10cm) and operated with hydraulic bench in the laboratory, all models in the same conditions in terms of temperature and for several times and is intended here all models are models of the notch-sections (semi-circular, v-notch and rectangular).

The values of discharge coefficient (cd) of the rectangular notch between (0.73-0.71) while the discharge coefficient (cd) of the V notch between (0.85- 0.78), while the discharge coefficient (cd) for the half-circular notch between are such that no (0.93- 0.88).

To find out the best form of notch weir took the coefficient of discharge (cd) function on it.

From above can be inferred that the weirs with a half-circular notch is the best in terms of hydraulic discharge measurement in rectangular notch weirs with and v-notch.