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 reater 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 Assignment 1. Answer:
Actually when the flow emerges from the throat area of venturi to enter into the diverging section, their is a negative pressure gradient i. , 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.
... as the water flow rate was increased, the pressure drop also increased, which is in accordance with Bernoulli’s equation. The discharge coefficient is a ratio ... experiment was from the coefficient of discharge of the orifice meter. The coefficient of discharge of the orifice meter had an error of 9. ... the liquid crest over the weir, had is the head loss due to liquid flow under the downcomer, and hhg is ...
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 meter calculates velocity by measuring the pressure head at both points before and after the narrowed throat. 3. coefficient of discharge depends on the state of the machine/system you are using. if you are using very textured tubes then this number will be higher. if how ever you are using very flexable tubes and fluid at different pressures this can also effect your results as the inflow and outflow may be different, or the cross sectional area of the tubes again chganging the pressure/flow and thus you.