From: "Stephen Izett stephen.izett@gmail.com" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] cooling modes
Date: Sat, 21 Nov 2020 07:00:32 +0800
References: <list-967076@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-967076@logan.com>
Message-Id: <666E66B3-D567-410E-BC4F-587A14577E6C@gmail.com>

Nice work Charlie.

Steve

> On 21 Nov 2020, at 6:50 am, Charlie England ceengland7@gmail.com =
<flyrotary@lancaironline.net> wrote:
>=20
> My (untested in combat) version for my radiator looks similar, but =
because the inlet is offset, I had to use a turning vane to get flow =
into the lower front of the core. The outside doesn't give a good idea =
on how 'tight' the inner surface is. I had to use expanding foam to fill =
the inside, then re-shape, then glass over the foam.  As I said, the =
back 1/4-1/3 of the diffuser tapers tightly to almost touch the core at =
the back.
>=20
> After observing both rotary and piston installations that work, I'm =
beginning to think that turning vanes may be the 'good enough' vs =
fighting for perfection in diffuser shape. My oil cooler core has a much =
more elaborate vane setup, driven by the very short duct length and even =
greater offset to the bottom edge of the core.
>=20
> Charlie
>=20
>=20
> On 11/20/2020 4:22 PM, Stephen Izett stephen.izett@gmail.com wrote:
>> Hi Roy
>>=20
>> Here is a photo of our Mocal 44 row oil cooler with diffuser. A K&M =
Streamline into a wedge.
>> Not sure of the dimensions of hand. The Mocal web site will have =
specs so you could get a rough idea of size.
>> I tested this one recently with a leaf blower approximating 100 knot =
air flow and in that test it was very even.
>>=20
>> Having said that, I tested our water radiator wedge diffuser when I =
built it years ago and had it reasonably even=20
>> measuring pressures across the exit face, but now instrumenting it in =
flight its flow is vastly uneven.
>>=20
>> I have found that the flow is dependant not only on getting the =
diffuser shape right according to the various papers (eg. K&W, London, =
Oblique Flow Diffusers - Streamline )
>> But importantly the environment it ends up in. The papers share data =
for ideal conditions with for example unobstructed exit air paths.
>> My thoughts now are that this has a significant impact on the =
performance and therefore the advantage of instrumenting in flight and =
reshaping for actual conditions.
>>=20
>> The data I collected yesterday of our H2O diffuser reveals that the =
air flow in various points across the face are very different.
>> Simplified, if I average the pressures at the five points I measured, =
then comparatively the back is up 20%, the centre up 25% and the front =
down 60% from that average figure.
>> I=E2=80=99m figuring a 20% difference is probably OK, but my front to =
back/middle difference of ~80% down in the front top of that radiator =
may hold significant room for improvement.
>> Further, my data suggests that as IAS rises those differences are =
amplified.=20
>> So I am now targeting the modifications for our worst case conditions =
of WOT sea level ~200hp and initial climb numbers of 115KIAS.
>>=20
>> Cheers.
>>=20
>> Steve Izett
>>=20
>>=20
>>=20
>>> On 21 Nov 2020, at 3:37 am, ROY GLENN rglenn14@sbcglobal.net =
<flyrotary@lancaironline.net> wrote:
>>>=20
>>> Could some ne post a photo of their wedge shape and dimensions.
>>> Thanks Roy
>>>=20
>>> --
>>> Homepage:  http://www.flyrotary.com/
>>> Archive and UnSub:   =
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>>=20
>=20
>=20
>=20
>  =09
> This email has been checked for viruses by Avast antivirus software.=20=

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>=20
>=20
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