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patep023

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## Homework Statement

A Venturi meter is constructed with an inlet diameterof 100 mm and a throat

diameter of 40 mm. The meter must be calibrated prior to leaving the factory.

The meter is installed in a 100 mm diameter water main with a mercury

manometer connected across the inlet and throat of the device. Calibration comprises the determination of the coefficient of discharge (Cd) for the meter at

various flow rates. Cd is defined as the ratio of the actual flow rate to the theoretical flow rate. At one particular flow rate, 0.012 m^3 of water is collected in one second having passed through the meter. The manometric levels differed by 375mm at this flow rate.

## Homework Equations

p1/ρg +v1^2/2g+z1=p2/ρg +v2^2/2g+z2

Q=v1A1=v2A2

Cd=mass flow rate actual/mass flow rate theoretical.

## The Attempt at a Solution

So the theoretical solution for mass flow rate is 0.012 m^3s^-1

I haven't plugged in the numbers but I have played around with the equations a lot. An image of the question can be accessed from the link. I got as far as to putting a lot of equations together and getting z1-z2=(v2^2-v1^2)/2g - (p1/p2)/ρwg and z1-z2=(p2-p1 - ρwgh +ρmgh)/ρwg where ρw is density of water and ρm is density of mercury. p1 and p2 are pressure at point 1 and 2. The answer is 0.98 but I don't know all the variables to put into get the actual value for the mass flow.

http://i.imgur.com/PgCasr0.png