A mechanical fan driven at the right speed ratio will move a lot more air than any electrical fan. One precaution with that home-brewed shroud- - - -be sure the fan blade is centered in the output. Looking at the shroud from the side, only half the fan blade depth should be inside the shroud. If the shroud totally encloses the blade, the volume it moves will be reduced dramatically.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!