X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao103.cox.net ([68.230.241.43] verified) by logan.com (CommuniGate Pro SMTP 5.2.0) with ESMTP id 2783034 for flyrotary@lancaironline.net; Sat, 08 Mar 2008 11:14:10 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.43; envelope-from=alventures@cox.net Received: from fed1rmimpo01.cox.net ([70.169.32.71]) by fed1rmmtao103.cox.net (InterMail vM.7.08.02.01 201-2186-121-102-20070209) with ESMTP id <20080308161330.IBZY17412.fed1rmmtao103.cox.net@fed1rmimpo01.cox.net> for ; Sat, 8 Mar 2008 11:13:30 -0500 Received: from BigAl ([72.192.137.74]) by fed1rmimpo01.cox.net with bizsmtp id ygDG1Y00D1cVYgg0000000; Sat, 08 Mar 2008 11:13:16 -0500 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: Oil Cooler re-visit Date: Sat, 8 Mar 2008 08:15:41 -0800 Message-ID: <000001c88137$a7c06f50$6401a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C880F4.999D2F50" 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_01C880F4.999D2F50 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Today I did my 'morning after' check and cross check on my analysis of = the flow data I presented yesterday. My calculation of the flow through the = core based on the exit velocity profile wasn't consistent with a check of diffuser ratio and average velocity . . . short story is - I had made a mistake. I had compensated for the flow area taken up by the tubes = twice; once in each of two steps of the calculations. =20 Making that correction, if the data is to be believed, is that the calculated flow through the core is 93% of the air approaching the = entrance of the scoop. The flow distribution isn't the greatest, but considering that the outside two rows of fins where the flow is slow have a tube on = only one side, there isn't much to be gained by a better distribution. =20 I'll be looking further into what is then the mystery of why the cooling capacity is lower than expected. Meanwhile, it appears that the = oil/coolant heat exchanger is the plan of choice. =20 Maybe the reason the Lyc oil cooler install worked so well was that the = Lyc didnt need much cooling in the first place =20 Not convinced that its a useful reference point unless he did what you = did and actually measured pressure differential across the cooler. =20 Mike Wills Mike; =20 I agree with your assessment. I was looking forward to meeting you last Wed. Sorry you couldn't make it. Another time. =20 Al ------=_NextPart_000_0001_01C880F4.999D2F50 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Today I did my ‘morning = after’ check and cross check on my analysis of the flow data I presented = yesterday. My calculation of the flow through the core based on the exit velocity = profile wasn’t consistent with a check of diffuser ratio and average = velocity . . . short story is – I had made a mistake. I had compensated for the = flow area taken up by the tubes twice; once in each of two steps of the calculations.

Making that correction, if the = data is to be believed, is that the calculated flow through the core is 93% of = the air approaching the entrance of the scoop. The flow distribution = isn’t the greatest, but considering that the outside two rows of fins where = the flow is slow have a tube on only one side, there isn’t much to be = gained by a better distribution.

I’ll be looking further = into what is then the mystery of why the cooling capacity is lower than = expected. Meanwhile, it appears that the oil/coolant heat exchanger is the plan of = choice.

Maybe the reason the Lyc = oil cooler install worked so well was that the Lyc didnt need much cooling in the = first place

Not convinced that = its a useful reference point unless he did what you did and actually measured pressure differential across the cooler.

Mike Wills

Mike;

I agree with your = assessment. I was looking forward to meeting you last Wed. Sorry you couldn’t = make it. Another time.

Al

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