X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao106.cox.net ([68.230.241.40] verified) by logan.com (CommuniGate Pro SMTP 5.1.10) with ESMTP id 2186421 for flyrotary@lancaironline.net; Thu, 19 Jul 2007 01:23:47 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.40; envelope-from=alventures@cox.net Received: from fed1rmimpo01.cox.net ([70.169.32.71]) by fed1rmmtao106.cox.net (InterMail vM.7.08.02.01 201-2186-121-102-20070209) with ESMTP id <20070719052308.MSDR1393.fed1rmmtao106.cox.net@fed1rmimpo01.cox.net> for ; Thu, 19 Jul 2007 01:23:08 -0400 Received: from BigAl ([72.192.132.90]) by fed1rmimpo01.cox.net with bizsmtp id RHP71X0071xAn3c0000000; Thu, 19 Jul 2007 01:23:07 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Oil cooler inlet Date: Wed, 18 Jul 2007 22:24:43 -0800 Message-ID: <000001c7c9cd$7eac7ae0$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C7C98A.70893AE0" 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 V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C7C98A.70893AE0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Good ideas TJ. I agree that the upper wall shape is not good. Didn't concern myself that much about it originally because I had been assured = that the negative pressure at the exit above the wing would take care of = things. NOT!!! =20 I think I would shape it such that there was no contraction of the = area, because; based on past experience with scoops, where you do not have external diffusion to help you out, any contraction in the duct causes = back pressure and air spilling around the scoop, especially if you are = ingesting the BL. Best if you can have continued expansion once past the = entrance. =20 Monty; you may well be right; it may take a combination. However, I did = put VGs in front of the entrance, and it did not make a noticeable = difference. They were only about 8" forward of the entrance because of the gear well that is there. I think I will try again with them further forward - on = the gear door covers; and make them a bit taller this time. =20 =20 Al =20 -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Thomas Jakits Sent: Wednesday, July 18, 2007 4:26 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Oil cooler inlet =20 Hi all, =20 please keep in mind that I am here only with theory at this time, also I = am excomunicato from PL-heaven (maybe that counts for something?? :)). =20 What I gathered so far from the cooling discussions, I would try the following in this case: =20 a) any of the lines I have drawn into the sketch OC scoop-03 b) to add a little, make sure the intake lip has a smooth lip, with the biggest possible radius on the inside c) IF your glass finish is "absolutely perfect" in front of the intake, = I'd sand it with 400 or 360 in flow direction: mask of the area and only = sand in one direction ( I would draw the block away from the intake...). The = idea is to rough up the surface and create miniature vortex generators=20 if c) does nothing d) Try out "real" vortex generators. =20 However, I believe (...if your sketch is sufficiently accurate) the most loss you see from "stall" in area B. The red line is rather conservative (the first one I tried in paint :)) Bue and Magenta should get you fairly close to streamline. Magenta = pushing towards Ed's "pinched ducts" system :)=20 =20 Personally I would try some foam insert before I would mess with turning vanes. AS your sketch looks you will not be done with a vane, as the air still slows too much because of the excessive retreat of the the upper = duct wall....=20 =20 Hope it helps! Stand to be corrected! =20 TJ ------=_NextPart_000_0001_01C7C98A.70893AE0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Good ideas TJ.  I agree that = the upper wall shape is not good. Didn’t concern myself that much = about it originally because I had been assured that the negative pressure at the = exit above the wing would take care of things.  NOT!!!

 

 I think I would shape it = such that there was no contraction of the area, because; based on past experience = with scoops, where you do not have external diffusion to help you out, any contraction in the duct causes back pressure and air spilling around the = scoop, especially if you are ingesting the BL.  Best if you can have = continued expansion once past the entrance.

 

Monty; you may well be right; it = may take a combination. However, I did put VGs in front of the entrance, and = it did not make a noticeable difference.  They were only about 8” = forward of the entrance because of the gear well that is there.  I think I = will try again with them further forward – on the gear door covers; and make them = a bit taller this time. 

 

Al

 

-----Original = Message-----
From: Rotary motors in = aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Thomas Jakits
Sent: Wednesday, July 18, = 2007 4:26 PM
To: Rotary motors in = aircraft
Subject: [FlyRotary] Re: = Oil cooler inlet

 

Hi all,

 

please keep in mind that I am here only with = theory at this time, also I am excomunicato from PL-heaven (maybe that counts for something?? :)).

 

What I gathered so far from the cooling = discussions, I would try the following in this case:

 

a) any of the lines I have drawn into the = sketch OC scoop-03

b) to add a little, make sure the intake lip = has a smooth lip, with the biggest possible radius on the = inside

c) IF your glass finish is "absolutely perfect" in front of the intake, I'd sand it with 400 or 360 in = flow direction: mask of the area and only sand in one direction ( I would = draw the block away from the intake...). The idea is to rough up the surface and = create miniature vortex generators

if c) does nothing

d) Try out "real" vortex = generators.

 

However, I believe (...if = your sketch is sufficiently accurate) the most loss you see from "stall" = in area B.

The red line is rather conservative (the = first one I tried in paint :))

Bue and Magenta should get you fairly close = to streamline. Magenta pushing towards Ed's "pinched ducts" = system :) 

 

Personally I would try some foam insert = before I would mess with turning vanes. AS your sketch looks you will not be done with = a vane, as the air still slows too much because of the excessive retreat of the = the upper duct wall....

 

Hope it helps!

Stand to be corrected!

 

TJ

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