Abrasive flow finishing

[Corey & Alicia Beaverson]

Second'ing Gary's post and continuing......
What got this whole thing started was whether or not bumps inside
intake/exhaust runners would be beneficial. I think the first and most
important distinction to make is that in the article that you mentioned, the
situation was an external flow. But the flow in an intake/exhaust runner would
be an internal flow.......i.e. water in a pipe.  Here, the Re # is still very
important and for laminar flows is a function of  fluid density, velocity, pipe
dia. and viscosity........IF the Re # is high enough to consider the flow
turbulent then the Re # is a strong function of the Moody Diagram which is a
plot of  Re # against surface roughness. What you will find is that in high Re
# flow the greater the surface roughness, the higher the friction factor and
the head loss will become greater as well. Now MY QUESTION to the group, is
this desireable?..........if there is a loss in pressure will the velocity go
up??..Bernoulli says yes.....what effect does that have???
    Generally speaking, in terms of port injection engines anyway I think that
the introduction of turbulence in the intake runner is a bad thing.....it will
only destroy energy.
When it comes to cylinder filling, that is a different story.......here
turbulence can be very desirable and looking at this again as a pipe flow
problem it is easy to see why, when a flowing fluid experineces a sudden
increase in pipe diameter i.e. port to cylinder there will always be some
"backflow"  (which induces turbulence) at the edges of the smaller
diameter....thus filling the entire area with fluid....a good thing!!
I don't think exhaust ports would ever benefit from turbluence inducing bumps,
again because of head loss problems.
comments?, comments?, comments!?