Mailing List flyrotary@lancaironline.net Message #11756
From: Al Gietzen <ALVentures@cox.net>
Subject: RE: [FlyRotary] Re: oil filter, pressure test, ewp
Date: Sat, 25 Sep 2004 17:29:49 -0700
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message

Aren't these types of oil pumps considered positive displacement pumps?  In other words, they displace a certain volume with every turn.  If that's the case, it would seem that a higher volume pump would be a good thing for cooling.  The extra volume would get bypassed at the regulator, and would get sucked right back out of the pan and sent back to the oil cooler.  Just seems like this would be a way to get more cooling out of a given cooler size.   It might not quite work that way in reality, but I'm just trying to think of anything that could help oil temps.  Not likely I'll be changing oil pumps. 

 

A higher flow rate can help, but for the same core, all it can do is decrease the delta T inlet to outlet (ignoring 2nd order effects like changes in heat transfer coeficient.  For the same oil temp out of the engine, decreasing the delta T will increase the average rejection temp, thereby increasing the total heat rejected.  If the system is air-side limited, and the delta T is already small, more flow isn’t going to help much.

 

Al

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