Everyone knows golf balls have dimples 'cuz that makes them fly farther
(more aerodynamic) than smooth balls would, right? In fact, Chrysler
experimented with a dimpled vinyl hood on one of their NASCAR contenders
back in the 60's - it apparently worked pretty well until the high-speed
wind shear ripped the vinyl top off the car..........
Well, I remember reading in a science mag a coupla years ago about how rough
surfaces are aerodynamically more efficient than smooth surfaces. A coupla
guys were experimenting with different surfaces and measuring liquid flow
(velocity) through a pipe. The pipe with the smooth surface had low
velocity because liquid running against the surface would shear and roll up
(like rolling a carpet up) until it got so big it would break away from the
surface and create turbulence, thus slowing overall velocity. If random
projections were present on the surface, however, the 'carpet rolls' never
got a chance to form because they were ripped apart immediately by the
projections. This led to higher velocity.
Strangely enough, if the projections were not random, but rather in a
pattern, flow was WORSE than with a smooth surface. Random projections
delivered approximately 15% improvement in flow velocities as compared to
smooth surfaces.
It would seem then, that the perfect pipe design (for intake and exhaust)
would have irregular random projections (I think they were talking on the
order of 2mm projections?) and direct the flow in a counter-clockwise
direction (in the northern Hemisphere). You could have a small-diameter
pipe to enhance flow velocity for low-end torque, and still have the mass
airflow (due to higher velocities) to get your higher-end hp.
OK, those of you with resources, start designing us some ultra-flow pipes!!!
I think the article was in "Nature" magazine about 2 years ago. Why Nature?
I think one of the studies referred to the Navy studying why fish
(particularly sharks) were rough-skinned so they could swim thru the water
faster. Seems the Navy was thinking about putting a similar surface on
their subs and/or ships to make them slide thru the water easier.
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