How wasteful is a cooling fan enclosure?

Question

Looking at the fan in the attached photo, its cage takes a lot of surface on both sides.

Does this cause a significant reduction of blowing efficiency or can it be ignored in the sense that it won't make much difference if the grilles are to be removed (apart from the obvious safety implications)?

Also, which impediment is causing more losses, the back (from where the air is coming from) or the front (to where the air is blown)?

Also, are there additional non negligible losses due to turbulences around the structure's wires or is it just the physically impenetrable blocking of the airflow?

Answer 1

The losses are significant, turbulence is large but also serves to distribute the jet differently than if it wasn't there. The rear guard is somewhat less lossy because both the peak velocity and the average velocity there is a bit lower and more than half the grill has inflowing air. Round wires are a really bad aerodynamic choice. Many fans with plastic grills have better grill shapes, but collect more dust and are harder to clean. Dirty ones are certainly worse than a clean wire grill.