Guessing the static pressure needed to produce flow rate
 

Dear All,

I have to guess the static pressure at pressure outlet - it has to produce (approximately) my desired mass flow rate.

I know the following:
- the area of the outlet
- the target mass flow rate
- air density can be approximated to be 1.2 kg/m^3
- from above three quantities, I can calculate air velocity through the outlet

Outlet is open to the atmosphere.
My operating pressure is set to zero.

How do I guess the static pressure at the pressure outlet?