Solution

We know that

 
Now  where Q is volume flow rate

(3)

(4)

(5)

Where

(6)

                                                                                                              
By 4 and 6, and substituting the known values we get

(7)

(8)

Assuming We get .

Reader should calculate Y by eq. 5 and verify that

use the data of problem 3 and calculate the orifice diameter for the following conditions:

1. When maximum pressure drop measured by pitot tube is 60 mm water.
2. When maximum pressure drop is 70 mm water and
3. When maximum pressure drop is 55 mm water.

Plot pressure drop Vs orifice diameter and discuss the variation of pressure drop Vs diameter curve.