Hydraulics Laboratory Experiment Report
Ahmed Essam Mansour
Section: "1", Monday 2-5 pm Title: Date: Venturi Meter and Orifice Meter 6 November, 2006
• To use the Venturi Meter and the Orifice Meter to measure the rate of discharge. • To determine the coefficient of discharge Cd for both the Venturi Meter and the Orifice Meter.
A Venturi meter and an Orifice are both instruments used for measuring the rate of discharge for a fluid flowing in a pipe. These instruments are based on the same principle which states the following: "The pressure difference between any two points on a tapering pipe through which the fluid is flowing depends on the change of levels and on the change in velocities and therefore on the volume rate of flow" Where the flow is led to narrow cross section, at which the velocity increase and hence a fall in the pressure occur. A Venturi Meter consists of a short converging conical tube leading to a cylindrical portion, called the throat, of smaller diameter of that of the pipeline, which is followed by a diverging section in which the diameter increases again to that of the main pipeline
An Orifice Meter consists of an orifice plate which has an opening in it smaller than the internal diameter of the pipeline, placed in a flange connecting the two portions of the pipeline.
The equation to be used to fine Q theoretical for the pipe line can be found as follows:
This can be written on the form;
Actually the discharge rate occurring in the pipe is smaller for the calculated theoretical values; that’s why a coefficient of discharge is to be evaluated for each instrument to be used then to calculate the actual rate of discharge:
Where Q actual in the experiment is calculated by;
The value of Cd is usually less than 1, for the Venturi Meter it is close to one, and for the Orifice it is about 0.65, due to the larger losses in the case of Orifice meter.
• • • • • Hydraulic...
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