X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao102.cox.net ([68.230.241.44] verified) by logan.com (CommuniGate Pro SMTP 5.1.10) with ESMTP id 2203396 for flyrotary@lancaironline.net; Fri, 27 Jul 2007 19:55:46 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.44; envelope-from=alventures@cox.net Received: from fed1rmimpo01.cox.net ([70.169.32.71]) by fed1rmmtao102.cox.net (InterMail vM.7.08.02.01 201-2186-121-102-20070209) with ESMTP id <20070727235509.JIML1428.fed1rmmtao102.cox.net@fed1rmimpo01.cox.net> for ; Fri, 27 Jul 2007 19:55:09 -0400 Received: from BigAl ([72.192.132.90]) by fed1rmimpo01.cox.net with bizsmtp id Unv91X0041xAn3c0000000; Fri, 27 Jul 2007 19:55:09 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Oil cooler inlet-what next? Date: Fri, 27 Jul 2007 16:57:04 -0800 Message-ID: <000c01c7d0b2$371d6d60$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000D_01C7D06F.28FA2D60" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 Importance: Normal In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_000D_01C7D06F.28FA2D60 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable I think that you should pursue one problem at a time until you have exhausted the chance of any improvement on that front. =20 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 =20 Monty; =20 I'm with you all the way on this. I'll admit to trying the easy first = to see if good things would happen; but no such luck. Not to make excuses; = but . .one of the downsides of this wing root installation is that its accessibility sucks . .er.. is not at all good. Taking the wing off to remove the cooler is not an easy undertaking; and even then; with the = scoop and fairing on, you can't get at it. It slides in and out end-wise; so clearance (read leakage gaps) is needed. So I do need to get better = data, and do whatever I can do toward determining a fix before opening things = up to make changes. =20 One of the things I hadn't quite figured was how to seal things up = without major dismantling. So about this "gorilla snot" (gees; there's got to = be a more household term for that) - that may be the ticket. Do you know = what happens to it when it gets hot - like over 200F? Will it stay in place; = and will it harden and make it impossible to ever get the cooler out without = a jackhammer? Is this a Home Depot item - or do I have to know someone in = the trade? =20 Thanks, =20 Al =20 =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 =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 =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. =20 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 =20 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. ;-) =20 I hate rats. =20 Monty ------=_NextPart_000_000D_01C7D06F.28FA2D60 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

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.

 

Monty;

 

I’m with you all the way on = this.  I’ll admit to trying the easy first to see if good things would happen; but = no such luck.  Not to make excuses; but . .one of the downsides of this = wing root installation is that its accessibility sucks . .er.. is not at all = good.  Taking the wing off to remove the cooler is not an easy undertaking; and = even then; with the scoop and fairing on, you can’t get at it. It = slides in and out end-wise; so clearance (read leakage gaps) is needed. So I do = need to get better data, and do whatever I can do toward determining a fix = before opening things up to make changes.

 

One of the things I hadn’t = quite figured was how to seal things up without major dismantling.  So = about this “gorilla snot” (gees; there’s got to be a more = household term for that) – that may be the ticket.  Do you know what = happens to it when it gets hot – like over 200F? Will it stay in place; = and will it harden and make it impossible to ever get the cooler out without a = jackhammer?  Is this a Home Depot item – or do I have to know someone in the = trade?

 

Thanks,

 

Al

 

 

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.

 

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.

 

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

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