From: "Charlie England ceengland7@gmail.com" <flyrotary@lancaironline.net>
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Date: Tue, 31 Jul 2018 09:12:51 -0500
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Subject: Re: [FlyRotary] Re: Using Fluidyne oil coolers as Primary Radiator
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Again, no way to know without testing, but if face area is going down
instead of up, and there's no additional core volume either, it's hard to
imagine it improving cooling. To get flow through the front half of the
core, I followed Tracy's advice & pinched the aft end very tight against
the core. Almost a 'French curve', with the aft end of the diffuser
touching the core, and curving outward as you move forward. To be clear, I
haven't flown it yet, but leaf blower tests show even flow using that
trick.

Have you considered reversing the angle of your wedge? When I looked at how
close the core is to my engine, I started wondering how much the radiant
energy from the engine could be affecting core efficiency. I also wondered
about the exit flow having even more energy scrubbed off by passing over
the 'random' surfaces of the engine, mount, etc. So I made my wedge
diffuser fit between the engine & the radiator. I'm hoping the fiberglass
shell will keep engine radiant heat away from the core, and it also opens
the option of  the exit air having a smooth exit duct, or flowing directly
out of the cowl, with no S turn on the exit; just one turn of less than 90
degrees. Again, not flying, so no guarantees that the idea has merit.

On flow rates, you'd *think* that air flow would be similar, but there are
several different types of core designs, even within the oil cooler subset.
The Lyc guys talk about significant performance differences between brands
that use different core designs. There's also the issue of liquid flow.
Will an oil cooler 'turbulate' water as effectively as it does thicker oil,
or could it allow some laminar flow of the water, meaning poorer heat
exchange? I certainly don't know. But it might be like antenna design. You
can measure differences, but when actually using a comm antenna, you can
rarely tell the difference between designs. The errors we make in feeding
the heat exchanger may totally overshadow performance differences between
core designs.

Charlie

On Tue, Jul 31, 2018 at 7:35 AM, Jeff Whaley jwhaley@datacast.com <
flyrotary@lancaironline.net> wrote:

> Charlie I agree with your analysis as interpreted from the drawing sent
> ... however it's not a surface doubling it's actually 210 total sq inches
> placed in a Vee (105 each half) Vs 247 total sq in placed in a slanted
> position. Yes in application there should be flow dividers to prevent all
> the air piling up at the back 3RD of VEE - I have done that leaf blower
> experiment with a couple of heater cores ... For the slanted single core it
> is also difficult to get air through the front half, combined with the fact
> that an engine/oil pan is parked on top.
>
> I will elaborate more: the air flow through the Vee has to make one "S"
> bend to pass through the cooler and exit the cowling, whereas with a
> slanted-up single radiator the air has to make one "S" bend to pass through
> the core and another "S" bend to make its way around the firewall and exit
> under the airframe, so from an airflow perspective the Vee is more
> efficient - as I see it.
>
> A concern is the flow rate through the two types of cores - I don't know
> the difference between a radiator core Vs an oil cooler core from the
> perspective of internal construction.  Are 0.75 inch lines large enough to
> flow enough coolant? There reason for consideration is the oil coolers are
> of the appropriate size and shape with AN fittings incorporated - though
> they each cost as much as one big radiator.
>
> Jeff
>
>
>
> 1st, let me say, 'I don't know'. :-)
>
> Having said that....
>
> If you're doubling the face area vs a single cooler perpendicular to the
> duct, then it will probably cool a bit better, but nowhere near twice as
> good. If you're feeding that configuration from a straight duct, my money
> would be on most of the flow being through the last third of each cooler.
> It looks like basically a two sided wedge, and I can say from experience
> that a wedge diffuser will do what I described, unless the downstream end
> is pinched down so it almost touches the face of the cooler. Perhaps a flow
> divider (more or less a diamond shape) to supply the pinch effect would
> balance the flow.
>
> It's easy enough to see the effect. Get a couple of junk coolers (anything
> would do to test, as long as they're the same cooler). Mount them in a
> cardboard duct using (wait for it...) duct tape, and feed it air using your
> leaf blower. Tie a thread (yard works better; it's lighter for it's cross
> section) to a thin stick, and move it around the exit faces. You'll quickly
> see where the air is moving through the cores (and where it's not).
>
> Charlie
>
>
> --
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:   http://mail.lancaironline.net:
> 81/lists/flyrotary/List.html
>
>

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<div dir=3D"ltr">Again, no way to know without testing, but if face area is=
 going down instead of up, and there&#39;s no additional core volume either=
, it&#39;s hard to imagine it improving cooling. To get flow through the fr=
ont half of the core, I followed Tracy&#39;s advice &amp; pinched the aft e=
nd very tight against the core. Almost a &#39;French curve&#39;, with the a=
ft end of the diffuser touching the core, and curving outward as you move f=
orward. To be clear, I haven&#39;t flown it yet, but leaf blower tests show=
 even flow using that trick.=C2=A0<div><br></div><div>Have you considered r=
eversing the angle of your wedge? When I looked at how close the core is to=
 my engine, I started wondering how much the radiant energy from the engine=
 could be affecting core efficiency. I also wondered about the exit flow ha=
ving even more energy scrubbed off by passing over the &#39;random&#39; sur=
faces of the engine, mount, etc. So I made my wedge diffuser fit between th=
e engine &amp; the radiator. I&#39;m hoping the fiberglass shell will keep =
engine radiant heat away from the core, and it also opens the option of=C2=
=A0 the exit air having a smooth exit duct, or flowing directly out of the =
cowl, with no S turn on the exit; just one turn of less than 90 degrees. Ag=
ain, not flying, so no guarantees that the idea has merit.<br><div><br></di=
v><div>On flow rates, you&#39;d *think* that air flow would be similar, but=
 there are several different types of core designs, even within the oil coo=
ler subset. The Lyc guys talk about significant performance differences bet=
ween brands that use different core designs. There&#39;s also the issue of =
liquid flow. Will an oil cooler &#39;turbulate&#39; water as effectively as=
 it does thicker oil, or could it allow some laminar flow of the water, mea=
ning poorer heat exchange? I certainly don&#39;t know. But it might be like=
 antenna design. You can measure differences, but when actually using a com=
m antenna, you can rarely tell the difference between designs. The errors w=
e make in feeding the heat exchanger may totally overshadow performance dif=
ferences between core designs.</div><div><br></div><div>Charlie<br><div cla=
ss=3D"gmail_extra"><br><div class=3D"gmail_quote">On Tue, Jul 31, 2018 at 7=
:35 AM, Jeff Whaley <a href=3D"mailto:jwhaley@datacast.com">jwhaley@datacas=
t.com</a> <span dir=3D"ltr">&lt;<a href=3D"mailto:flyrotary@lancaironline.n=
et" target=3D"_blank">flyrotary@lancaironline.net</a>&gt;</span> wrote:<br>=
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">Charlie I agree with your analysis as interp=
reted from the drawing sent ... however it&#39;s not a surface doubling it&=
#39;s actually 210 total sq inches placed in a Vee (105 each half) Vs 247 t=
otal sq in placed in a slanted position. Yes in application there should be=
 flow dividers to prevent all the air piling up at the back 3RD of VEE - I =
have done that leaf blower experiment with a couple of heater cores ... For=
 the slanted single core it is also difficult to get air through the front =
half, combined with the fact that an engine/oil pan is parked on top.<br>
<br>
I will elaborate more: the air flow through the Vee has to make one &quot;S=
&quot; bend to pass through the cooler and exit the cowling, whereas with a=
 slanted-up single radiator the air has to make one &quot;S&quot; bend to p=
ass through the core and another &quot;S&quot; bend to make its way around =
the firewall and exit under the airframe, so from an airflow perspective th=
e Vee is more efficient - as I see it.<br>
<br>
A concern is the flow rate through the two types of cores - I don&#39;t kno=
w the difference between a radiator core Vs an oil cooler core from the per=
spective of internal construction.=C2=A0 Are 0.75 inch lines large enough t=
o flow enough coolant? There reason for consideration is the oil coolers ar=
e of the appropriate size and shape with AN fittings incorporated - though =
they each cost as much as one big radiator.<br>
<br>
Jeff<br>
<br>
<br>
<br>
1st, let me say, &#39;I don&#39;t know&#39;. :-)<br>
<br>
Having said that....<br>
<br>
If you&#39;re doubling the face area vs a single cooler perpendicular to th=
e duct, then it will probably cool a bit better, but nowhere near twice as =
good. If you&#39;re feeding that configuration from a straight duct, my mon=
ey would be on most of the flow being through the last third of each cooler=
. It looks like basically a two sided wedge, and I can say from experience =
that a wedge diffuser will do what I described, unless the downstream end i=
s pinched down so it almost touches the face of the cooler. Perhaps a flow =
divider (more or less a diamond shape) to supply the pinch effect would bal=
ance the flow.<br>
<br>
It&#39;s easy enough to see the effect. Get a couple of junk coolers (anyth=
ing would do to test, as long as they&#39;re the same cooler). Mount them i=
n a cardboard duct using (wait for it...) duct tape, and feed it air using =
your leaf blower. Tie a thread (yard works better; it&#39;s lighter for it&=
#39;s cross section) to a thin stick, and move it around the exit faces. Yo=
u&#39;ll quickly see where the air is moving through the cores (and where i=
t&#39;s not).<br>
<br>
Charlie<br>
<br>
<br>--<br>
Homepage:=C2=A0 <a href=3D"http://www.flyrotary.com/" rel=3D"noreferrer" ta=
rget=3D"_blank">http://www.flyrotary.com/</a><br>
Archive and UnSub:=C2=A0 =C2=A0<a href=3D"http://mail.lancaironline.net:81/=
lists/flyrotary/List.html" rel=3D"noreferrer" target=3D"_blank">http://mail=
.lancaironline.net:<wbr>81/lists/flyrotary/List.html</a><br>
<br></blockquote></div><br></div></div></div></div>

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