Why Apex Seals Fail

[t_g_farrell]

Vex it sounds like your analysis is right on. Check out what RB has been offering
for years now. Looks almost like what your describing.



They describe it here:

http://www.racingbeat.com/RX7-1975-1...tem/11488.html

The description talks about heat transfer being improved due to the grooves but
I wonder if thats some purposeful FUD and the real solution is along the lines
that your describing. It would all depend on exactly what they groove and
where I guess.

This is a great thread by the way.

[vex]

Originally Posted by t_g_farrell

Vex it sounds like your analysis is right on. Check out what RB has been offering
for years now. Looks almost like what your describing.



They describe it here:

http://www.racingbeat.com/RX7-1975-1...tem/11488.html

The description talks about heat transfer being improved due to the grooves but
I wonder if thats some purposeful FUD and the real solution is along the lines
that your describing. It would all depend on exactly what they groove and
where I guess.

This is a great thread by the way.

Unfortunately it's not. This specific modification is done to every coolant passage thereby causing a turbulent boundary layer (or depending on the variables a completely turbulent flow) to be formed in each passage. The result would remain an 'unbalanced' distribution so long as the hydraulic diameter differences are not touched. This modification works for two reasons; first it causes a turbulent boundary layer to form while also increasing the 'flow' between the various fins (IE turbulence) further decreasing the amount of mass of the fluid entrapped exterrior of the boundary layer. This means coolant exposed to the grooves transfers more heat away from the aluminum and into the boundary layer. Whether this cooling effect is more uniform than a equal flow distribution is unknown (at least to me). This being the case one could toy with the variables in the grooves (depth, spacing, thickness, etc) to achieve uniform cooling of the various passages, but that would be more work than I think it's worth.

I know that's confusing, but it's the best I got without drawing a picture of what I mean. Infernosig (sp?) may be able to explain what I mean better.

[t_g_farrell]

Yep, thats why I said "almost" and "it would all depend". Obviously you wouldn't
groove every opening as RB has done and I'm sure it would take some intensive
R&D to optimize it.

Whats interesting is there are still so many improvements that can and will be
made to the rotary to make it better. Think of how many refinements and
designs have been wrought on the piston engine in the last 100 years to
get it where it is today. The rotary has barely been in production for 50 years
so far.