Originally Posted by monkamarm2000
5 degrees instant yeah, but gradual won't, specially at our speeds. go super sonic then yeah all kinds a things can happen. Just look at a nose cone itself, its got angles on the tip of more than 5 degree's, now look at the base of the blades, how much compensation there shows you how much shrouding happens with flow, you'll notice it isnt much, if it were then blades would not start till much further outside the hub. And the air is so tight even around a spinner, that look at a ds fan. the ds uses by pass air around the spinner to cool the motor, look right down the fan, and you will see just how small the slot is. And you could be talking about Klaus? he posted a lot of data on here along with papers and pdf's and illustrations, great reading for sure.
the lower is the speed the lower is Reynolds number.
With low Re air has an heavy work to do to stay put an enlarging duct where speed slows down and pressure increases.
I think that duct should have minor direction changes and the least possible section changes,most important whenever area increases.
No problem with a spinner pointing into the air,serious problems may arise from a spinner pointing back.
I can't understand what you are meaning speaking of ds.