It doesn't matter. What happens to a plastic bag if you hold it in front of a fan? The air goes in, then comes right back. It can backflow right back past the fanblades. Why? Because it'* not a positive-displacement type blower. There'* a return path.
The air can't do this with a supercharger. There'* no return path, so the pressure can build in the manifold in reserve for the engine to use when the intake valves open.
In other words, an 'open blade' fan won't do you any good. It can MOVE air, but it can't build pressure.
All electric fans are rated in CFM with NO LOAD OR RESTRICTION. This is how the e-ram electric supercharger scams people. They give a high CFM rating because their fan was tested in an open room. As soon as you put it in your intake, it loses far more than 50% of it'* efficiency.
If we were in a lab, I could show you a practical demonstration of this in 5 minutes.