Received-SPF: none
 receiver=logan.com; client-ip=129.116.87.170; envelope-from=mark.steitle@austin.utexas.edu
Content-class: urn:content-classes:message
MIME-Version: 1.0
Content-Type: text/plain;
	charset="US-ASCII"
Content-Transfer-Encoding: quoted-printable
Subject: RE: [FlyRotary] Re: BMW and EWP
Date: Mon, 21 Mar 2005 11:42:16 -0600
Message-ID: <87DBA06C9A5CB84B80439BA09D86E69EC080BB@MAIL01.austin.utexas.edu>
Thread-Topic: [FlyRotary] Re: BMW and EWP
Thread-Index: AcUuMKdLsfv6zvSkQbeJeyKgUNw1cQADAn1Q
From: "Mark R Steitle" <mark.steitle@austin.utexas.edu>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

It seems that we may be missing the real objective here.  What we're
really trying to do is cool metal engine parts, not heat water.  So, the
question becomes, what approach cools the metal engine parts best, high
or low flow?  Methinks high works best. =20

Mark S.
>=20
> I had looked at it as:
> High Flow - engine can't heat the water as much as it would if the
flow
> were slower and there was more time to heat the water, resulting in
less
> temp rise in water across engine and more uniform temps in the block.
> Water emerges from block not much hotter than it went in.  Water
doesn't
> stay in the radiator long enough to be exposed to air flow long enough
> to be cooled very much.  Good news: it doesn't *have* to be cooled
much
> - it's not all that hot.
> Low Flow - coolant spends more time in engine and gets hotter.
Greater
> dT across engine block, coolant hotter exiting engine and entering
> radiator.  Radiator has to draw more heat out of the coolant to get it
> back to acceptable block entry temp, but has more time to do it on
> account of lower flow.
> What I hadn't seen, is how apparently wide a range of flows would
> produce acceptable results.  I suppose a better radiator (more flue
> area, better air flow, etc. - better cooling per in^3) would reduce
the
> volume requirement.  Lower limit on flow would seem to be that flow at
> which the temperature gradient across the engine becomes unacceptable.
> Thanks for the details ... Jim S.


>>  Homepage:  http://www.flyrotary.com/
>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html