X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ispmxmta05-srv.windstream.net ([166.102.165.166] verified) by logan.com (CommuniGate Pro SMTP 5.1.10) with ESMTP id 2202880 for flyrotary@lancaironline.net; Fri, 27 Jul 2007 14:18:05 -0400 Received-SPF: pass receiver=logan.com; client-ip=166.102.165.166; envelope-from=montyr2157@alltel.net Received: from ispmxaamta04-gx.windstream.net ([71.29.244.202]) by ispmxmta05-srv.windstream.net with ESMTP id <20070727181725.MJTA19750.ispmxmta05-srv.windstream.net@ispmxaamta04-gx.windstream.net> for ; Fri, 27 Jul 2007 13:17:25 -0500 Received: from Thorstwin ([71.29.244.202]) by ispmxaamta04-gx.windstream.net with SMTP id <20070727181725.UMFB24166.ispmxaamta04-gx.windstream.net@Thorstwin> for ; Fri, 27 Jul 2007 13:17:25 -0500 Message-ID: <007201c7d07a$679c9110$6501a8c0@Thorstwin> From: "M Roberts" To: "Rotary motors in aircraft" Subject: Oil cooler inlet-what next? Date: Fri, 27 Jul 2007 13:17:34 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_006F_01C7D050.7E9DF270" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_006F_01C7D050.7E9DF270 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Al, I think that you should pursue one problem at a time until you have = exhausted the chance of any improvement on that front. You have too many variables and you are not eliminating any in these = tests. You are merely making unknown possible improvements/detriments to = lots of problems all at once.=20 From what I can tell, you should be getting more static pressure at the = core than you are even with the BL problem and the wall being a = non-ideal shape (as you stated). This could be due to leakage, or it = could be due to separation and duct stall due to the boundary layer = ingestion problem. There is no way to know for sure with the info you = have.=20 I am not convinced by the 9 in of water 5/8 from the surface that you = should get 6 in at the cooler face. Absent a methodical rake test from = the wing out to below the scoop, and all along the front of the scoop it = is impossible to make much of conclusion from one point of data. What is = it at .25 in from the surface, along the entire length? If 1/4 of your = duct has slow boundary layer air going into it (which unfortunately is = the poorly contoured surface of the duct) you may have a disaster for = flow inside the duct. If the flow separates from the top wall, the = unseparated high energy flow will not diffuse properly. What is = happening at the end of the duct towards the wheel well? All unknown = variables.=20 First order of business is eliminate ANY chance of leakage past the = cooler. Eliminate this variable first. This includes the area near the = tanks where there is no core, only tubes. This should be sealed up = completely as well as the perimeter of the core. Then retest with no = other changes. Make sure you use the same location for your manometer = and use foam around the end of the tube. That way your data will be = apples to apples. Once armed with this info you can proceed to the next step. If it were = me, I would fix the duct contour (no gaps in the metal allowed) and then = retest. Then I think I would try a mixing divider vane in the inlet = before the change in curvature. That way the high energy air is mixed = with the low energy air BEFORE it has to begin diffusion. If this fails = I would move on to sealing the gear door and external VGs Forget about quick fixes and start killing rats until you find the one = causing the majority of the problem. Right now you are only "wounding" = or perhaps missing "the" rat all together while flailing at them with a = big blunt instrument. Get out the rifle and kill them (verifiably, = unquestionably dead) one by one until the problem is solved. ;-) I hate rats. Monty ------=_NextPart_000_006F_01C7D050.7E9DF270 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Al,
 
I think that you should pursue one = problem at a=20 time until you have exhausted the chance of any improvement on that=20 front.
 
You have too many variables and you are = not=20 eliminating any in these tests. You are merely making unknown possible=20 improvements/detriments to lots of problems all at once.
 
From what I can tell, you should be = getting more=20 static pressure at the core than you are even with the BL problem and = the wall=20 being a non-ideal shape (as you stated). This could be due to leakage, = or it=20 could be due to separation and duct stall due to the boundary layer = ingestion=20 problem. There is no way to know for sure with the info you have. =
 
I am not convinced by the 9 in of water = 5/8 from=20 the surface that you should get 6 in at the cooler face. Absent a = methodical=20 rake test from the wing out to below the scoop, and all = along the=20 front of the scoop it is impossible to make much of conclusion from = one=20 point of data. What is it at .25 in from the surface, along the entire = length?=20 If 1/4 of your duct has slow boundary layer air going into it (which=20 unfortunately is the poorly contoured surface of the duct) you may have = a=20 disaster for flow inside the duct. If the flow separates from the top = wall, the=20 unseparated high energy flow will not diffuse properly. What is = happening=20 at the end of the duct towards the wheel well? All unknown variables.=20
 
First order of business is eliminate = ANY chance of=20 leakage past the cooler. Eliminate this variable first. This includes = the area=20 near the tanks where there is no core, only tubes. This should be sealed = up=20 completely as well as the perimeter of the core. Then retest with no = other=20 changes. Make sure you use the same location for your manometer and use = foam=20 around the end of the tube. That way your data will be apples to=20 apples.
 
Once armed with this info you can = proceed to the=20 next step. If it were me, I would fix the duct contour (no gaps in = the=20 metal allowed) and then retest. Then I think I would try = a mixing=20 divider vane in the inlet before the change in curvature. That = way the=20 high energy air is mixed with the low energy air BEFORE it has=20 to begin diffusion. If this fails I would move on to sealing = the gear=20 door and external VGs
 
Forget about quick fixes and start = killing rats=20 until you find the one causing the majority of the problem. Right now = you are=20 only "wounding" or perhaps missing "the" rat all together while flailing = at them=20 with a big blunt instrument. Get out the rifle and kill them = (verifiably,=20 unquestionably dead) one by one until the problem is solved.=20 ;-)
 
I hate rats.
 
Monty
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