flyrotary@lancaironline.net Mailing List Archive

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 = Vi +Vt with Vt the component tangential to the face of the > 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 = > vi with vt = 0 probably means maximum cooling effect from the air flow which > (one reason) is why straight in flowing ducts (where Vb = Vi) cool better > than one with twists and turns. > > Ed > -------------------------------------------------- > From: "Ed Anderson" <eanderson@carolina.rr.com> > Sent: Sunday, September 11, 2011 6:08 PM > To: "Rotary motors in aircraft" <flyrotary@lancaironline.net> > 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 = 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 = 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 = Vi because Vt = 0, straight duct >> condition only. >> >> Now in figure 12.6 the incoming oblique air flow does have two components >> (Vi and Vt) relative to the orientation of the block - Vt is not zero here >> and of course neither is Vi. So Vb = Vi + Vt. If you have a good copy >> 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 = 0 and Vb = 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 expression >> 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 much >> smaller or zero and Vb = 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 vector >> 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 for >> 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" <ceengland@bellsouth.net> >> Sent: Sunday, September 11, 2011 3:13 PM >> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net> >> 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 fig >>> 12-6. And quite a few of the terms don't seem to be defined at all (this >>> 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/List.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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