From: "Stephen Izett stephen.izett@gmail.com" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Water Temps
Date: Mon, 30 Nov 2020 16:36:30 +0800
References: <list-990047@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Message-Id: <C6906920-08EF-4D75-9153-6C18876F0AA1@gmail.com>

Thanks Steve
I always appreciate your scientific understanding and explanations.
Much appreciated.

Steve


> On 30 Nov 2020, at 1:34 am, Steven W. Boese SBoese@uwyo.edu =
<flyrotary@lancaironline.net> wrote:
>=20
> Steve,
>=20
> Your cooling system is a closed system with two heat exchangers, one =
being the engine adding heat and the other being the radiator removing =
heat.  The delta T of the coolant across the engine and the delta T =
across the radiator must be the same.  Since there isn't much you can do =
to change the characteristics of the engine as a heat exchanger, there =
isn't much you can do to change the observed delta T.
>=20
>  As you change the characteristics of the radiator side of the system, =
the inlet and outlet temperatures will change together until a steady =
state is reached and the radiator can remove the amount of heat produced =
by the engine.  With increasing power, both the inlet and outlet =
temperatures will rise by the same amount until the mass air flow =
through the radiator together with the OAT results in the required =
amount of heat removed from the system.  The goal is to keep the average =
of the inlet and outlet temperatures within reason.  Delta T by itself =
isn't a good indicator of the suitability of the radiator side of the =
overall system. =20
>=20
> This all assumes that a thermostat isn't being used.  With a =
thermostat, the delta T across the radiator will be variable until the =
bypass is completely closed, at which point the above behavior will be =
seen.
>=20
> The attached plot shows the effect of changing the air inlet and =
outlet sizes but the delta T is essentially constant. =20
>=20
> =20
> Steve Boese
> RV6A, 1986 13B NA, RD1C, EC2
>=20
> From: Rotary motors in aircraft <flyrotary@lancaironline.net> on =
behalf of Stephen Izett =
stephen.izett@gmail.com<flyrotary@lancaironline.net>
> Sent: Sunday, November 29, 2020 1:08 AM
> To: Rotary motors in aircraft <flyrotary@lancaironline.net>
> Subject: [FlyRotary] Water Temps
> =20
> =C2=A1=C3=9F This message was sent from a non-UWYO address. Please =
exercise caution when clicking links or opening attachments from =
external sources.
>=20
>=20
> Hi there people
>=20
> Has anyone got data of actual delta T from inlet to outlet of their =
water radiators
> And if you do, what is the size of your inlet feeding the radiator, =
IAS and OAT at those data points.
>=20
> We have ~30 square inches of air into the water cooling
> Water into the engine is these data points was 180F
>=20
> Delta T KIAS    OAT
> 10F        153      54
>  8F         115      54
>=20
> I=C2=A1=C2=AFm now fine tuning our water cooling and wanting to =
compare with other known data.
>=20
> Thanks
>=20
> Steve Izett
> Glasair SuperIIRG Renesis 4 Port
>=20
>=20
>=20
>=20
> --
> Homepage:  http://www.flyrotary.com/
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> <inlet and outlet area comparison s.jpg>--
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