odd hypothetical-attaching box fans in a cube

You take six standard-issue box fans, all the same make and model. You attach them together so that they form a cube, with each fan facing inward, using some airtight attachment process (like welding or something) which is stronger than the material the fans are made of.

You put all six fans on a simultaneous switch and turn them all on blowing inward at the same time.

What would happen and why?

For example, would the air from each fan just blow out through the blades of the other fans?? Or would it explode and simply blow one of the fans’ components completely out of the cube? If so which one and why?

Or would one of the fans fail, the motor burn out, and then all of the air flow out that one side? If so, which one and why?

(I realize that it would depend on the type of fan used–but in my mind it’s a cheap, Wal-mart $15 box fan, but discussion of fan variables would be welcomed)

thanks all

The air pressure inside the cube will increase to the point where the fans are unable to push any more air in. This doesn’t take much with a typical cheap box fan. At that point all six fans will continue running, their blades merely churning up air and making noise and heat - the same as if you took a single fan and completely blocke doff the outflow side. You’ll probably get a lot of turbulence inside the cube too.


Box fans are passive (for lack of a better word). If they can’t push the air, they don’t really care, they just keep spinning. If you try this experiment, don’t worry about sealing up the corners with anything airtight. Unless you’re box fan’s have shrouds you’ll still have all the space between the blades and the edge of the box itself. Now if you were using air pumps…

If you put a box fan against a wall or face down on the floor, it will bog down a bit, but it will keep running. The same happens when the fan is in a window and a gust of wind blows the other direction. It takes more energy to blow against resistance, and the typical box fan doesn’t have the horsepower to keep the revs up.

I was just about to say that, more or less.

Box fans aren’t compressors. With all of that space between the blades and the box, air will just be pulled in at the middle of the box and squirt out the corners where there’s several inches of open space.

A corollary to what the OP seems to have in mind would be to take X hydraulic pumps and directly connect their outputs. Then just wait to see which pump has the weaker seals and where the hydraulic fluid starts to squirt from.