flyrotary@lancaironline.net Mailing List Archive

The only thing to add to that document is that the internal shape of most of the ducts shown are all wrong. The race car in figure 19 has it about right, though. The bell shaped ducts shown in most of the drawings force the air to separate from the duct wall soon after the entrance, creating the turbulent flow he is talking about in other sections of the document. A trumpet shaped duct, one that doesn't flair out until right before the cooler, will increase cooling capacity up to 30%.

On Tuesday, July 9, 2019, 2:01:26 PM EDT, Marc Wiese cardmarc@charter.net <flyrotary@lancaironline.net> wrote:

Interesting discussion recently found---

This document is shared with you in response to various questions arising out of spinner airflow characteristics. It is TOO LENGTHY to include in full, but you may find parts interesting enough to share.

[Here's a French version of the English document I found that's easier to see/read.]

http://acversailles.free.fr/documentation/08~Documentation_Generale_M_Suire/Moteur/Refroidissement/Conception/Cooling_systems_for_automotive_conversion~H.Mayer.pdf

[I find it odd that he misses a major point that did emerge from those decades of engine cooling research: cooling fin pitch is very important!

Nowadays, most folks use the free software from GM_Harrison and others to design their coolers... but the delta P in automotive applications is generally less, but the airflow is greater. So a different fin pitch is appropriate for our relatively higher delta P (much higher speed through the air than a car) but lower airflows (to minimize cooling drag) applications.]