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Originally Posted by vex
How did I miss this thread?
Let me see if I can help in adding my schooling into the mix (Hurrah for Fluid Dynamics being applicable in all situations dealing with flow).
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Fluid dynamics is applicable, but I think that heat transfer principles and metal expansion rates have more bearing in this situation.
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Originally Posted by vex
What I mean by that is that if you have a single source flowing unevenly into the various passages the incompressible nature of the fluid is going to dictate that the area with the higher pressure is going to output the more mass of the fluid (all other things being equal). Consequently ensuring you're getting an equal flow rate prior to the passage entrance would be paramount.
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Technically, all passages have the same pressure across them (all tied to the same hose on one end, all rising the same amount, all exiting to atmosphere) The issue is that all passages have different flow rates due to their differing hydraulic diameter. The flow rate does not need to be consistent, as there is very little heat to be rejected at the beginning of the intake stroke as compared to the compression region.
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Originally Posted by vex
If however there is no leakage and the input is simply just feeding it through the water ports where the waterpump seals, then the issue is indeed hardware related. Consequently since we can assume a uniform pressure distribution (not only for this experiment but for the real world application) we can see that the differences is going to be directly related to the hydraulic diameter and boundary layer conditions of the passages. This provides us with an easy enough solution as well.
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We can solve for the hydraulic diameter given the (measured) flow much more easily than we can compute the other direction. Once again, this is not important, heat transfer is much more important here. Fast moving water is not always better.
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Originally Posted by vex
First and foremost; enlarging the hydraulic diameter of the passages will allow for a more unified flow condition between all ports in question. There remains however a finite amount of space to achieve that. The other option that can be excersized as well would be to instill a turbulent boundary layer on only some of the passages.
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Enlarging the passages is not always the best solution. What racing beat is doing is much better. They are increasing the surface area that is exposed to the cooling fluid while also inducing turbulence which improves convective heat transfer significantly.
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Originally Posted by vex
Why only some? Think of it this way: we have a large passage that is putting out a lot of fluid. The issue is attempting to balance the passages to output the same amount of fluid at the end of the day. To do this we can lower the friction a majority of the fluid is exposed to in the other passages, in essence allowing for a faster flow to be achieved on smaller passages, while the undisturbed boundary layer on the larger passage causes the flow to slow down when compared to the tripped boundary layer of the smaller passages.
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Once again, consistent passage-to-passage flow will not make this problem go away. The issue is much more complicated than that. The heat transferred to the coolant in each passage needs to be equal to the heat generated in the nearby chamber and transferred through the aluminum housing. I am guessing that Mazda did some research on this, as the coolant passages on top of the housing (low heat rejection to the coolant) have restrictors in them.
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Originally Posted by vex
The solution will consist of finding the appropriate balance of the two.
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I admire your attitude and your desire to apply your knowledge to any problem, I just don't want you wasting a lot of time chasing wild geese.