multi-fan pressure map for ventilation

[mangineer]

Any tips on how to derive a pressure map analysis of a simple duct system with two fans on each end. The intake has a push type fan and the exit has a pull type fan. I can conduct an analysis simply with one pushing fan, but I'm a bit confused when it comes to adding another fan on the exit side. Thanks!

 

[ChasBean1]

You need to start with curves for each "push" (supply) and "pull" (exhaust) fan. flow vs. pressure.

Let's say for argument's sake you have one of each running. From there, we have numerous variables. If they are both the exact same fans/systems and completely even ducts, you'd have a neutral pressure midway between the two and a high pressure at the outlet of the supply fans of a magnitude equal to the low pressure at the inlet side of the exhaust fans...

I think the pressure would drop linearly from fan outlets, to the mid points and decrease linearly to the exhaust fan inlets.

CB

 

[mangineer]

Interesting. I would like to utilize the same size fans on both ends and for simplicity this will be a simple straight duct setup, so by obtaining fan curves for both intake fan on only and another where the exhaust fan is on only I can get the flow and velocity. From there I should be able to conduct a pressure map using velocity pressure and static pressure.

 

[ChasBean1]

What are you trying to accomplish? Is this just academic?

 

[mangineer]

Yes, they don't offer this subject at my school unfortunately. Fluid mechanics is the only subject that touches on flow, but not on fan selection, fan curves and pressure maps. Thanks for your input.