Radial (blower) fan, better to have both sides open?

Hardware Cooling
1

I got a couple of “naked” blower fans; Delta makes these specifically for you to design the housing around it. Talking about this one in particular:

Is it better to close off the side with the mounting bracket completely, or would leaving it (partially) open help?

2

The Radial fans I have make an effort to feed air into the rotor from both sides.

3

Thanks for the quick reply!

I sort of figured it might help because the impeller blades are more or less symmetrical across the plane, at least on this fan design.

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