• For both meters it was noted from plots that the difference in pressures are directly related to the rate of discharge.
• Coefficient of discharge have a varying value depending on the rate of discharge, where in the Venturi meter the value of Cd increase gradually at first with increasing the rate of discharge till a point approaching one, then started to descend with further increment in the rate of discharge.
• The Coefficient of discharge " Cd
greater than 1
• When the Head losses where plotted with the discharge rate, the following results were accomplished;
-- The head losses increased as the rate of discharge
increased for both meters.
--When the rate of discharge was taken to be the
theoretical value, an unexpected result was obtained
Actually when the flow emerges from the throat area of venturi to enter into the diverging section, their is a negative pressure gradient i.e, in layman terms fluid is trying to flow from low pressure region to high pressure region according to Bernoulli equation. In this adverse pressure gradient, there is boundary layer separation, in simple terms, the fluid leaves the surface of the wall. Due to this there can be energy loss or the fluid can't recover the pressure fully leading to head loss. So if divergent section is long that means more gradual diverging section, due to which the adverse pressure gradient is less so less chance of boundary separation and hence less loss. Also large diverging section will ensure proper development of flow, i.e. fluid sticking to the wall back after separation.
2.The Uses of the Venturi Meter
A venturi meter is also called a venturi flowmeter. It is used to calculate the velocity of fluids in running through a pipeline. The fluid may be a liquid or a gas. The meter consists of a pipe with a narrowing throat that expands back to it's original diameter on the other side of the choke point. The venturi...
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