Return-Path: Received: from [65.54.169.107] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2904128 for flyrotary@lancaironline.net; Wed, 24 Dec 2003 13:20:55 -0500 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Wed, 24 Dec 2003 10:20:54 -0800 Received: from 67.24.244.200 by bay3-dav77.bay3.hotmail.com with DAV; Wed, 24 Dec 2003 18:20:54 +0000 X-Originating-IP: [67.24.244.200] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Streamline Vs Parabolic Ducts/Diffusers Date: Wed, 24 Dec 2003 13:20:53 -0500 MIME-Version: 1.0 X-Mailer: MSN Explorer 7.02.0011.2700 Content-Type: multipart/alternative; boundary="----=_NextPart_001_0001_01C3CA20.C1F68A30" Message-ID: X-OriginalArrivalTime: 24 Dec 2003 18:20:54.0652 (UTC) FILETIME=[AB4803C0:01C3CA4A] ------=_NextPart_001_0001_01C3CA20.C1F68A30 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Not sure I follow this correctly. It sounds like you are saying the the = performance of the parabolic is infearior to the streamlined. From my pe= rspective, the one that results in the maximum pressure at the face of th= e heat exchanger, wins. =20 Isn't Pd more on the parabolic? Who cares if it is a linear increase o= r not? Or I may have missed something........ Tracy ----- Original Message ----- From: Ed Anderson Sent: Wednesday, December 24, 2003 12:39 PM To: Rotary motors in aircraft Subject: [FlyRotary] Streamline Vs Parabolic Ducts/Diffusers For those of you interested in such stuff. Attached is a gif of how different ducts affect the conversion of kinetic energy in the airflow t= o dynamic pressure. It appears that the streamline duct's unique curve controls th= e growth in diffuser area such that the non-linear growth in area (blue cur= ve) causes the dynamic pressure recovery to follow a linear curve (yellow li= ne) and that is the key to the more effective pressure recovery of dynamic pressure . The parabolic duct curve on the other hand results in an apparent linear growth in diffuser area which apparently forces the press= ure recovery to under go a non-linear development which possibly accounts for more loss. Not certain I understand exactly why, but it appears to h= ave to do with the difference in changing velocity of the air molecules near = the duct wall, boundary layers, separation and wall friction between the two type diffusers. Any aerodynamic types out there with a different interpretation? Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com >> Homepage: http://www.flyrotary.com/ >> Archive: http://lancaironline.net/lists/flyrotary/List.html ------=_NextPart_001_0001_01C3CA20.C1F68A30 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Not sure I fol= low this correctly.  It sounds like you are saying the the performan= ce of the parabolic is infearior to the streamlined.  From my perspe= ctive, the one that results in the maximum pressure at the face of the he= at exchanger,  wins. 
  Isn't Pd more on the pa= rabolic?  Who cares if it is a linear increase or not?   O= r I may have missed something........
 
Tracy<= /DIV>
 
----- Original Message -----
F= rom: Ed Anderson
Sent: W= ednesday, December 24, 2003 12:39 PM
Subject: [FlyRotary] Streamline Vs Parabolic Ducts/Diffusers
 
For those of you interested in such stuff.  At= tached is a gif of how
different ducts affect the conversion of kineti= c energy in the airflow  to
dynamic
pressure.  It appears= that the streamline duct's unique curve controls the
growth in diffus= er area such that the non-linear growth in area (blue curve)
causes th= e  dynamic pressure recovery to follow a linear curve (yellow line)<= BR>and that is the key to the more effective pressure recovery of dynamic=
pressure .  The parabolic duct curve on the other hand results i= n an
apparent linear growth in diffuser area which apparently forces t= he pressure
recovery to under go a non-linear development which possib= ly accounts
for more loss.  Not certain I understand exactly why,= but it appears to have
to do with the difference in changing velocity= of the air molecules near the
duct wall, boundary layers, separation = and wall friction between the two
type diffusers.

Any aerodynam= ic types out there with a different interpretation?

Ed AndersonRV-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com=
>>  Homepage:  http://www.flyrotary.com/
>>&= nbsp; Archive:   http://lancaironline.net/lists/flyrotary/List.= html
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