The only thing the support frame for an electric fan does is restrict some of the airflow, no matter where it's located. The flaps Ed is talking about are in the shroud to allow more ram air through at highway speed- - - -air that can't pass through the hole in the shroud around the fan fast enough. At low speed, the suction of the fan holds the flaps closed.
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!