X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.123] verified) by logan.com (CommuniGate Pro SMTP 5.2.15) with ESMTP id 3765269 for flyrotary@lancaironline.net; Sun, 19 Jul 2009 23:28:02 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.123; envelope-from=eanderson@carolina.rr.com Received: from computername ([75.191.186.236]) by cdptpa-omta02.mail.rr.com with ESMTP id <20090720032724658.YWRP28563@cdptpa-omta02.mail.rr.com> for ; Mon, 20 Jul 2009 03:27:24 +0000 From: "Ed Anderson" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: K&W Stream Duct Explanation Date: Sun, 19 Jul 2009 23:27:19 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0013_01CA08C8.76817F00" X-Mailer: Microsoft Office Outlook, Build 11.0.5510 Thread-Index: AcoI2zOY1j0Lj90zSFG0n3mhtPQOaAADW4Zw X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 In-Reply-To: Message-Id: <20090720032724658.YWRP28563@cdptpa-omta02.mail.rr.com> This is a multi-part message in MIME format. ------=_NextPart_000_0013_01CA08C8.76817F00 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Not familiar with the Chisel or tapered description, George. I may know it as a "wedge" type? If the Wedge type, all I can tell you is I did quite a bit of searching trying to find some technical data on it. The only thing I found was wedge shapes used in supersonic diffusers to slow air down through use of shock waves (created by supersonic airflow) for inlet to jet engines. I never found anything on it regarding sub-sonic flow or for heat exchangers. Anything that will slow air down, increase the pressure before the core and not cause a lot of eddies and turbulence will probably cool. But, can't really comment on how effective they may be compared to say the "StreamLine duct". Yes, the streamline duct is generally a bit too long for the size cores we use and our cowl lengths - if you implement a full streamline duct. That is why I have a small section in my paper on why a truncated streamline duct might still offer some decent pressure recovery. Since the streamline duct bell shape is not (or should not be) larger than your core that end should not pose a problem, unless, of course, you have your radiator canted/inclined and even then K&W addresses that as well, although my paper does not. Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of George Lendich Sent: Sunday, July 19, 2009 9:41 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: K&W Stream Duct Explanation Ed, Because of insufficient room under cowl, many are using the chisel or tapered (my name for it) shaped chamber rather than the bell shaped. To me, it looks to be, like one side of the bell shaped chamber, or like squeezing a bell shape down to one side. Have you studied this approach and do you think it's comparable. George (down under) Hi Gang I came across a abstraction of K&W's theory of the Streamline duct that I put together a number of year ago. While it is my interpretation and therefore subject to error, I have not found anything in the intervening years that indicates a misunderstanding. While it is not exactly light reading, I think it is easier to follow than K&W. In any case, I thought I would make it available to promote understanding and discussion {:>)) of one approach to cooling our installations. This paper targets four topic areas: * Diffusers In General * StreamLine Duct * Importance of Inlet to Core area ( Ai/AB ratio) * Truncation of StreamLine Duct Best Regards Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm __________ Information from ESET NOD32 Antivirus, version of virus signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com _____ -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html __________ Information from ESET NOD32 Antivirus, version of virus signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ------=_NextPart_000_0013_01CA08C8.76817F00 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Not familiar with the Chisel or = tapered description, George.  I may know it as a “wedge” = type?    If the Wedge type, all I can tell you is I did quite a bit of searching = trying to find some technical data on it.  The only thing I found was = wedge shapes used in supersonic diffusers to slow air down through use of = shock waves (created by supersonic airflow) for inlet to jet engines.   I = never found anything on it regarding sub-sonic flow or for heat = exchangers.  Anything that will slow air down, increase the pressure before the core = and not cause a lot of eddies and turbulence will probably cool.  But, = can’t really comment on how effective they may be compared to say the = “StreamLine duct”. 

 

Yes, the streamline duct is = generally a bit too long for the size cores we use and our cowl lengths – if = you implement a full streamline duct.  That is why I have a small = section in my paper  on why a truncated streamline duct might still offer some = decent pressure recovery.  Since the streamline duct bell shape is not (or = should not be) larger than your core that end should not pose a problem, = unless, of course,  you have your radiator canted/inclined and even then = K&W addresses that as well, although my = paper does not.

 

Ed

 

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of George Lendich
Sent: Sunday, July 19, = 2009 9:41 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = K&W Stream Duct = Explanation

 

Ed,

Because of insufficient room under cowl, many = are using the chisel or tapered (my name for it) shaped chamber rather than = the bell shaped. To me, it looks to be, like one side of the bell shaped = chamber, or like squeezing a bell shape down to one side. Have you studied = this approach and do you think it's comparable.

George (down under)

Hi Gang

 

I came across a abstraction of  K&W’s theory of the Streamline duct that I put together a number of year = ago.  While it is my interpretation and therefore subject to error, I have not = found anything in the intervening years that indicates a = misunderstanding.  While it is not exactly light reading, I think it is easier to follow = than K&W.

 

In any case, I thought I would make it available to = promote understanding and discussion {:>)) of one approach to cooling our installations.

 

This paper targets four topic = areas:

 

  • Diffusers = In General
  • StreamLine Duct =
  • Importance of Inlet to Core area ( Ai/AB ratio)
  • Truncation of StreamLine Duct

 

 

Best Regards

 

Ed

 

 

Ed Anderson

Rv-6A N494BW Rotary Powered

Matthews, NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.r= otaryaviation.com/Rotorhead%20Truth.htm

 



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