Two fans - different flow... what happens?

[Nimbus1951]

What happens if you place two fans at each end of a tube (maximum length about 20 cms). One of the fans has an airflow of f.ex. 35 CFM and the other has an airflow of 25 CFM.
What happens with the total air flow? Will the 25CFM fan be superfluous? Will the 25CFM fan even slow down the 35CFM? Or are they strongest together?
Bottom line - is there any idea in using two fans in series?

Regards,
Nimbus

 

[beatle]

There may be an idea in using 2 fans in series if the tube is sufficiently long enough that the flow from the first fan has dropped below the output of the second fan. At what point this happens, I'm not sure. It sounds like overkill for a computer case.

 

[Lizardman]

There is no real benefit from putting two case fans right on top of one another they just end up interfering with each other. A long tube is different though.