Return-Path: Received: from fed1rmmtao08.cox.net ([68.230.241.31] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 572680 for flyrotary@lancaironline.net; Sat, 18 Dec 2004 20:01:55 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.31; envelope-from=ALVentures@cox.net Received: from BigAl ([68.7.14.39]) by fed1rmmtao08.cox.net (InterMail vM.6.01.04.00 201-2131-117-20041022) with ESMTP id <20041219010125.MUHA27771.fed1rmmtao08.cox.net@BigAl> for ; Sat, 18 Dec 2004 20:01:25 -0500 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] cooler thoughts Date: Sat, 18 Dec 2004 17:01:32 -0800 Message-ID: <000001c4e566$47a35d50$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C4E523.39801D50" 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 V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C4E523.39801D50 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable =20 The problem might simply be that the pulses are hitting high pressures = and fatiguing the reasonably flimsy evap cores. There's also the = possibility that the pulses hit a resonant vibration at some point, which causes the failure. =20 It would be interesting to see a trace of these pulses, and they may be important; but I am skeptical about them being the primary cause unless = your cooler is near the engine outlet, and you have rigid (solid metal) = lines. These pulses are high frequency, and would not be expected to propagate = well in a somewhat viscous fluid and flexible lines. The pulse energy is dissipated along the way with the energy going into the fluid. =20 The existence of resonances is questionable for the same reasons. Self damping. =20 I can put my hand on the line or my cooler tank with the engine = running(with a glove on, of course) and feel no trace of any kind of vibration. But, there is a couple feet of steel braid flex line, and dual filter unit between the engine and the cooler, and a robust cooler; so this may not apply. =20 Al ------=_NextPart_000_0001_01C4E523.39801D50 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

 

The problem = might simply be that the pulses are hitting high pressures and fatiguing the reasonably = flimsy evap cores.  There's also the possibility that the pulses hit = a resonant vibration at some point, which causes the failure.

 

It would be interesting to see a = trace of these pulses, and they may be important; but I am skeptical about = them being the primary cause unless your cooler is near the engine outlet, and you = have rigid (solid metal) lines.  These pulses are high frequency, and = would not be expected to propagate well in a somewhat viscous fluid and flexible lines.  The pulse energy is dissipated along the way with the = energy going into the fluid.

 

The existence of resonances is = questionable for the same reasons.  Self damping.

 

I can put my hand on the line or = my cooler tank with the engine running(with a glove on, of course) and feel = no trace of any kind of vibration.  But, there is a couple feet of = steel braid flex line, and dual filter unit between the engine and the cooler, = and a robust cooler; so this may not apply.

 

Al

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