Designing an orifice plate to increase the pressure in a pipe

[shekarharsha]

Homework Statement

I am doing an experiment , where air is flowing through a square pipe of 95mm x95mm cross section with a mass flow rate of say 500slpm, now i want to chock the flow in order to increase the pressure in the pipe up to 4bar (absolute) max by using an orifice plate at the end of the pipe. now i want to find the orifice diameter, for which i get the desired pressure in the pipe.

Relevant Equations

now i know for chock condition : P/Po<.528
where p- 1 atm
Po- 3+1.01325=4.013bar(absolute) inside pipe

say for 3.013bar absolute pressure
pressure ratio :
P/Po = 14.7psi/43.707psi = 0.33
which means its chocked flow
now i want to find diameter or area of orifice :
so could anyone help me

 

[jrmichler]

There are two orifice flow (search the term) equations for flow through an orifice. One is for choked flow, the other for non-choked flow. The criteria that you used in your post tells you which equation to use. You know the pressure, gas properties of air, and flow rate, and the only unknown is the orifice diameter.