X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTP id 2463718 for flyrotary@lancaironline.net; Fri, 09 Nov 2007 13:48:51 -0500 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=eanderson@carolina.rr.com Received: from edward2 ([24.74.103.61]) by cdptpa-omta01.mail.rr.com with SMTP id <20071109184813.KAOA6760.cdptpa-omta01.mail.rr.com@edward2> for ; Fri, 9 Nov 2007 18:48:13 +0000 Message-ID: <001d01c82300$d478ae30$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Total,duct, Ambient or Velocity???? Date: Fri, 9 Nov 2007 13:46:24 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001A_01C822D6.EB64B2D0" 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_001A_01C822D6.EB64B2D0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Yes, Jarrett, it would be very interesting to design a cooling system = using CFD, fabricate, install and test it to see the results. =20 Ed ----- Original Message -----=20 From: H & J Johnson=20 To: Rotary motors in aircraft=20 Sent: Friday, November 09, 2007 11:40 AM Subject: [FlyRotary] Re: Total,duct, Ambient or Velocity???? > But, semantics aside, yes, I agree, lower exit pressure is what=20 > you are after and that does not always equate to larger exit duct=20 > area. In fact, if the air heated by the core flows through a=20 > nozzle it might even produce thrust and lower exit pressure using=20 > a smaller exit. But, in general, I still believe that in most of=20 > our cases, we are short of the level of duct design that would=20 > reliably permit that. What we need is someone to invest in one of=20 > those $$$$ Computer Fluid Flow software programs and see what they=20 > would reveal.=20 >=20 > Ed=20 >=20 >=20 > Ed,=20 >=20 > I have to disagree with the big $$$ CFD idea. Until I see proper=20 > exit ducts and every effort made to do things right inlet=20 > wise....CFD is a waste of time. I have yet to see an installation=20 > at the level of refinement where CFD would start to make sense.=20 > You can get to 90% of optimum by following a few simple guidelines=20 > and some fairly simple math.=20 >=20 > 1.) do a heat balance at the cruise condition to figure out how=20 > much air you need to ingest.=20 >=20 > 2.) Size your inlet appropriately.=20 >=20 > 3.) Provide a real exit duct.=20 >=20 > 4.) Use a cowl flap.=20 >=20 > 5.) Do some testing with oil and tufts to make improvements.=20 >=20 > A properly done CFD will only get you another 5% beyond these=20 > simple steps that are within reach of mere mortals. In fact if the=20 > guy/gal doing the CFD work is not intimately familiar with the=20 > situation and what sort of assumptions to make/conditions to=20 > assign it is very likely that the results will be less successful=20 > that the empirical method.=20 >=20 > In other words CFD=3Ddecimal dust.=20 >=20 >=20 > Monty=20 Well.. I haven't spent $$$ on it but SolidWorks now comes w/ a version = of CosmosFloWorks in the package in 2008.. I've got the software so I = may give it=20 a whirl.. I was waiting to test it before I commented but.. since = people are talking directly about it.. :-) Jarrett -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_001A_01C822D6.EB64B2D0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Yes, Jarrett,  it would be very =  interesting to=20 design a cooling system using CFD, fabricate, install and test it to see = the=20 results. 
 
Ed
----- Original Message -----
From:=20 H & J=20 Johnson
Sent: Friday, November 09, 2007 = 11:40=20 AM
Subject: [FlyRotary] Re: = Total,duct,=20 Ambient or Velocity????

> But, semantics aside, yes, I agree, lower exit pressure is = what=20
> you are after and that does not always equate to larger exit = duct=20
> area.  In fact, if the air heated by the core flows = through a=20
> nozzle it might even produce thrust and lower exit pressure = using=20
> a smaller exit.  But, in general, I still believe that = in most=20 of
> our cases, we are short of the level of duct design that = would=20
> reliably permit that.  What we need is someone to invest = in one=20 of
> those $$$$ Computer Fluid Flow software programs and see = what they=20
> would reveal.
>
> Ed
>
>
> = Ed,=20
>
> I have to disagree with the big $$$ CFD idea. Until = I see=20 proper
> exit ducts and every effort made to do things right = inlet=20
> wise....CFD is a waste of time. I have yet to see an = installation=20
> at the level of refinement where CFD would start to make = sense.=20
> You can get to 90% of optimum by following a few simple = guidelines=20
> and some fairly simple math.
>
> 1.) do a heat = balance=20 at the cruise condition to figure out how
> much air you need = to=20 ingest.
>
> 2.) Size your inlet appropriately.
> =
>=20 3.) Provide a real exit duct.
>
> 4.) Use a cowl flap. =
>=20
> 5.) Do some testing with oil and tufts to make improvements. =
>=20
> A properly done CFD will only get you another 5% beyond these =
> simple steps that are within reach of mere mortals. In fact = if the=20
> guy/gal doing the CFD work is not intimately familiar with = the=20
> situation and what sort of assumptions to make/conditions to =
>=20 assign it is very likely that the results will be less successful =
>=20 that the empirical method.
>
> In other words = CFD=3Ddecimal dust.=20
>
>
> Monty

Well.. I haven't spent $$$ on it but SolidWorks now comes w/ a = version=20 of

CosmosFloWorks in the package in 2008..  I've got the software = so I=20 may give it

a whirl.. I was waiting to test it before I commented but.. since = people=20 are talking

directly about it..  :-)

 

Jarrett

--

Homepage:  http://www.flyrotary.com/

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