X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao104.cox.net ([68.230.241.42] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTP id 2462572 for flyrotary@lancaironline.net; Thu, 08 Nov 2007 20:20:23 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.42; envelope-from=alventures@cox.net Received: from fed1rmimpo01.cox.net ([70.169.32.71]) by fed1rmmtao104.cox.net (InterMail vM.7.08.02.01 201-2186-121-102-20070209) with ESMTP id <20071109011945.HZRR25184.fed1rmmtao104.cox.net@fed1rmimpo01.cox.net> for ; Thu, 8 Nov 2007 20:19:45 -0500 Received: from BigAl ([72.192.143.193]) by fed1rmimpo01.cox.net with bizsmtp id ARKk1Y00G4AaN600000000; Thu, 08 Nov 2007 20:19:44 -0500 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Total,duct, Ambient or Velocity???? Date: Thu, 8 Nov 2007 17:19:51 -0800 Message-ID: <000001c8226e$a0da30e0$6401a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C8222B.92B6F0E0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C8222B.92B6F0E0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit My comments in red. Be careful not to describe the elephant by feeling just one part. Al G. If I'm understanding you correctly, it appears that you need dynamic pressure ( flow) that turns into a high static pressure (at the Rad face). To maintain this high static pressure, the dynamic flow must be free of turbulence, which is associated with flow separation from the duct walls. Hence the need for proper divergent angles. There must be good pressure drop across the Rad, not too high or you lose heat transfer, not too low as to create excess drag (an over-simplifcation, and likely the reverse is true, high pressure drop will results in hi drag because it takes all the energy out of the air, low pressure drop would generally be less drag, but my mean insufficient heat transfer area). There must be some turbulence within the duct fins to enhance heat transfer, but not too much as to create restrictions. I still feel a low pressure area behind the rad would be beneficial. (it would, flow through the core is a function of the delta P; unless otherwise limited) George ( down under ------=_NextPart_000_0001_01C8222B.92B6F0E0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

My comments in = red. Be careful not to describe the elephant by feeling just one = part.

 

Al G. =

If I'm understanding you = correctly, it appears that you need dynamic pressure ( flow) that turns into a = high static pressure (at the Rad face).

To maintain this high = static pressure, the dynamic flow must be free of turbulence, which is = associated with flow separation from the duct walls. Hence the need for proper divergent angles.

 

There must be good pressure = drop across the Rad,  not too high or you lose heat transfer, not too = low as to create excess drag = (an over-simplifcation, and likely = the reverse is true, high pressure drop will results in hi drag because it takes all = the energy out of the air, low pressure drop would generally be less drag, = but my mean insufficient heat transfer area). There must be some turbulence within the duct fins to enhance heat transfer, but not too = much as to create restrictions.

 

I still feel a low pressure = area behind the rad would be beneficial. (it would, flow through the core is a function of the delta P; unless = otherwise limited) =

=

George ( down = under

 

 

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