[secant0give]

I think part of the idea may be to reduce turbulence behind the blade so the next blade passes through nice clean air. Although it should do so mostly, as it's advancing through the air and the infeed air should be pretty clean.

Also any time you reduce turbulance you reduce wasted energy so I guess it's an attempt to make as much of the air leaving the TE of the prop blade to travel rearward and thus generate the maximum ammount of thrust. When you have turbulance a certain ammount of the the air in the props wake is moving in random directions. Some of this will add to the thrust and some not. if you can get it to orderly travel in the right direction it should all add to the thrust.

High reving props fly in a funny regeime, even tho' the Renolds number is not super high, (this is due to the the chord of the airfoil being quite short), the tips still can get fairly close to the speed of sound. So you have an odd situation, in that you have a low Re at a transonic airspeed.

Propellers and exactly how very work is a very interesting and complex subject and I don't fully understand the greater part of it.