Return-Path: Received: from imf22aec.mail.bellsouth.net ([205.152.59.70] verified) by logan.com (CommuniGate Pro SMTP 4.2b8) with ESMTP id 321377 for flyrotary@lancaironline.net; Wed, 14 Jul 2004 14:14:38 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.70; envelope-from=atlasyts@bellsouth.net Received: from [65.11.54.150] by imf22aec.mail.bellsouth.net (InterMail vM.5.01.06.08 201-253-122-130-108-20031117) with ESMTP id <20040714181402.SUQI1779.imf22aec.mail.bellsouth.net@[65.11.54.150]> for ; Wed, 14 Jul 2004 14:14:02 -0400 User-Agent: Microsoft-Entourage/10.1.4.030702.0 Date: Wed, 14 Jul 2004 14:13:43 -0400 Subject: Re: [FlyRotary] Re: New Scoop From: Bulent Aliev To: Rotary motors in aircraft Message-ID: In-Reply-To: Mime-version: 1.0 Content-type: multipart/alternative; boundary="B_3172659225_70336137" > This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --B_3172659225_70336137 Content-type: text/plain; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable Al, what is the volume of your radiator core, not overall. I=B9m trying to fi= t about 5-600 cub=B2 Bulent On 7/14/04 1:57 PM, "Al Gietzen" wrote: > Subject: [FlyRotary] New Scoop > =20 > Steve; > =20 > There are all kinds of things one could say about trying to make the scoo= p > ideal, effective, low drag, etc; and then when you face the reality of fi= tting > to your plane, you can=B9t do it. So it=B9s what works for you. I=B9ll add a = few > comments for whatever it=B9s worth. > =20 > The intake area of the scoop should be fine. > =20 > One would like to slow (expand) and turn the air entering the scoop in a > manner that maintains surface attachment for max pressure recovery and mi= nimum > drag. This takes a much longer scoop throat than you have. The air ente= ring > will trip to turbulent at the abrupt corner behind the B.L dam. This wil= l > result in poor flow and pressure distribution, with most of the air going > toward the back of the scoop. I don=B9t know what happens in your installa= tion > downstream from the actual scoop, but you might consider some internal ba= ffles > but get a more uniform distribution if the rad is close to the scoop. > =20 > The boundary layer dam that you have is high drag, and may be close enoug= h to > the entrance lip that backup of the B.L. flow will be ingested into the s= coop > =AD or it could result in some external diffusion (pressure recovery) and a= llow > the scoop to work just fine. The idea in the B.L. =B3bleed=B2 is to try to d= ivert > that flow somewhere else, generally off to the sides. That would requir= e a > much more gradual diverter angle. > =20 > I made a much more gradual bend in the wall of my scoop (pic) attached. > Still, in doing flow tests, I found flow separation and turbulence which = lead > uneven flow distribution. I added to baffles in the scoop get it fairly > uniform. It could be that some of the turbulence was a result of the tes= t rig > setup, although I thought I had a long enough duct from the blower to > straighten things out. > =20 > The squared off internal corners will add frictional drag, but probably n= ot > significant in overall picture. > =20 > But, hey =AD try it. If it gives you the cooling you need, you=B9ve got 90% o= f the > battle won. If you feel you need to reduce drag, you can consider that a= t > your leisure.=20 > =20 > Al > =20 --B_3172659225_70336137 Content-type: text/html; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable Re: [FlyRotary] Re: New Scoop Al, what is the volume = of your radiator core, not overall. I’m trying to fit about 5-600 cub&= #8221;
Bulent

On 7/14/04 1:57 PM, "Al Gietzen" <ALVentures@cox.net> wrote= :

Subject: [FlyRotary] New Scoop
 
Steve;
 
There are all kinds of things one could say about trying to make the scoop = ideal, effective, low drag, etc; and then when you face the reality of fitti= ng to your plane, you can’t do it.  So it’s what works for = you.  I’ll add a few comments for whatever it’s worth.
 
The intake area of the scoop should be fine.
 
One would like to slow (expand) and turn the air entering the scoop in a ma= nner that maintains surface attachment for max pressure recovery and minimum= drag.  This takes a much longer scoop throat than you have.  The = air entering will trip to turbulent at the abrupt corner behind the B.L dam.=  This will result in poor flow and pressure distribution, with most of= the air going toward the back of the scoop.  I don’t know what h= appens in your installation downstream from the actual scoop, but you might = consider some internal baffles but get a more uniform distribution if the ra= d is close to the scoop.
 
The boundary layer dam that you have is high drag, and may be close enough = to the entrance lip that backup of the B.L. flow will be ingested into the s= coop – or it could result in some external diffusion (pressure recover= y) and allow the scoop to work just fine.  The idea in the B.L. “= bleed” is to try to divert that flow somewhere else, generally  o= ff to the sides.  That would require a much more gradual diverter angle= .
 
I made a much more gradual bend in the wall of my scoop (pic) attached. &nb= sp;Still, in doing flow tests, I found flow separation and turbulence which = lead uneven flow distribution.  I added to baffles in the scoop get it = fairly uniform.  It could be that some of the turbulence was a result o= f the test rig setup, although I thought I had a long enough duct from the b= lower to straighten things out.
 
The squared off internal corners will add frictional drag, but probably not= significant in overall picture.
 
But, hey – try it. If it gives you the cooling you need, you’ve= got 90% of the battle won.  If you feel you need to reduce drag, you c= an consider that at your leisure.
 
Al
 


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