X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from exchange.carey.wa.edu.au ([118.82.44.212] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with ESMTPS id 5121049 for flyrotary@lancaironline.net; Sun, 11 Sep 2011 19:35:09 -0400 Received-SPF: none receiver=logan.com; client-ip=118.82.44.212; envelope-from=stevei@carey.asn.au Received: from exchange.carey.local ([10.10.0.5]) by exchange.carey.local ([10.10.0.5]) with mapi; Mon, 12 Sep 2011 07:34:28 +0800 From: To: Date: Mon, 12 Sep 2011 07:34:33 +0800 Subject: Re: [FlyRotary] Re: K & W Konfusion Thread-Topic: [FlyRotary] Re: K & W Konfusion Thread-Index: Acxw21kXJs3U8/hZTS+FqAB/SDNb4g== Message-ID: <48F398C0-EA40-44AA-A463-4D9ACAB8FFC6@carey.asn.au> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 I can relate Ed. I've spent some hours trying to understand and get their symbols together!!= ! Steve Izett On 12/09/2011, at 6:59 AM, Ed Anderson wrote: > > One, additional thing might be worth porting out is that with the vector > quantity Vb =3D Vi +Vt with Vt the component tangential to the face of th= e > core - as you might imagine, you don't get a lot of cooling contribution = due > to Vt, as theoretically it doesn't contribute (much) to the flow through = the > core (at least that is how I read it). Therefore the condition where vb = =3D > vi with vt =3D 0 probably means maximum cooling effect from the air flow = which > (one reason) is why straight in flowing ducts (where Vb =3D Vi) cool bett= er > than one with twists and turns. > > Ed > -------------------------------------------------- > From: "Ed Anderson" > Sent: Sunday, September 11, 2011 6:08 PM > To: "Rotary motors in aircraft" > Subject: [FlyRotary] Re: K & W Konfusion > >> Hi Charlie, >> >> Having pulled my hair out over some things in Chapter 12 of K& W, I can >> empathize. Let me see if I can help you with this particular question. >> >> As you know, Vb is a vector quantify having both magnitude and direction >> and here is composed of two vector quantities: Vi - (vector in line or >> incident with the core) and Vt (vector tangential to the face of the >> core). In this case ( a special case of the straight duct) Vt =3D 0. No= , >> the first chapter does NOT spell this out, so you did not miss it, but >> when you examine figure 12.6 you will see it. >> >> In your first reference the Vt value =3D 0 (they do not point this out) = and >> Vb is therefore equal solely to Vi (or the vector parallel to the duct, >> straight into the core). So here Vb =3D Vi because Vt =3D 0, straight d= uct >> condition only. >> >> Now in figure 12.6 the incoming oblique air flow does have two component= s >> (Vi and Vt) relative to the orientation of the block - Vt is not zero he= re >> and of course neither is Vi. So Vb =3D Vi + Vt. If you have a good cop= y >> and look carefully you can see that at the bottom of the vector triangle >> it shows Vb as the vector sum of Vi and Vt- and Vb is pointed in the >> direction of the airflow through the core (or parallel to the holes >> through the core or perpendicular to the core face). >> >> If you look at figure 12-7, the same vector combination is there and a >> bit easier to see. So in effec,t your first reference to Vb in chapter >> 12 is a special case of the overall vector components of the airflow (Vi >> and Vt) except in that case Vt =3D 0 and Vb =3D Vi. >> >> So it is probably more correct to say that Vb is the vector sum of the >> incident and tangential vectors of airflow or Vb is the vector expressi= on >> of the airflow through the core. >> >> What is missing in figure 12.6 is the showing the vector sum of Vb AFTER >> it exits the core. If they did, what you would probably see is Vt muc= h >> smaller or zero and Vb =3D Vi (since the duct is straight after the core= ). >> So if the vector sum on the one side of the core is Vb then it will also >> be Vb on the opposite side of the core - however the values of the vecto= r >> components vi and vt will be different (if not a straight duct) - but >> their sum will remain the same - vb. >> >> At least that is the way I read it - and no, I've never found and K&W fo= r >> dummies - if you do please let me know. >> >> >> Dummy Ed >> >> Edward L. Anderson >> Anderson Electronic Enterprises LLC >> 305 Reefton Road >> Weddington, NC 28104 >> http://www.andersonee.com >> http://www.eicommander.com >> >> >> -------------------------------------------------- >> From: "Charlie England" >> Sent: Sunday, September 11, 2011 3:13 PM >> To: "Rotary motors in aircraft" >> Subject: [FlyRotary] K & W Konfusion >> >>> Anyone else having problems interpreting K & W's chapter 12 on cooling? >>> >>> I confess to only having available (downloaded) chapters on inlets & >>> cooling, but their use of terms is a bit hair-pulling for me. For >>> instance, VsubB is defined on the 1st page of the chapter as 'velocity = of >>> the air ahead of the block' & diagrammed that way in fig 12-1, then it'= s >>> apparently diagrammed as the velocity *leaving* the cooling block in fi= g >>> 12-6. And quite a few of the terms don't seem to be defined at all (thi= s >>> may be due to my failure to take a physics course in college, & the 30+ >>> year interval since my one semester of Calculus...). >>> >>> If there's a 'K&W for Dummies' book, please recommend a source... >>> >>> Charlie >>> >>> -- >>> Homepage: http://www.flyrotary.com/ >>> Archive and UnSub: >>> http://mail.lancaironline.net:81/lists/flyrotary/List.html >>> >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: >> http://mail.lancaironline.net:81/lists/flyrotary/List.html >> > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/Lis= t.html The contents of this email are confidential and intended only for the named= recipients of this e-mail. If you have received this e-mail in error, you = are hereby notified that any use, reproduction, disclosure or distribution = or the information contained in this e-mail is prohibited. 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