X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from poplet2.per.eftel.com ([203.24.100.45] verified) by logan.com (CommuniGate Pro SMTP 5.3.1) with ESMTP id 4085928 for flyrotary@lancaironline.net; Sun, 17 Jan 2010 16:30:01 -0500 Received-SPF: none receiver=logan.com; client-ip=203.24.100.45; envelope-from=lendich@aanet.com.au Received: from sv1-1.aanet.com.au (mail.aanet.com.au [203.24.100.34]) by poplet2.per.eftel.com (Postfix) with ESMTP id 75CBD173802 for ; Mon, 18 Jan 2010 05:29:23 +0800 (WST) Received: from ownerf1fc517b8 (203.171.92.134.static.rev.aanet.com.au [203.171.92.134]) by sv1-1.aanet.com.au (Postfix) with SMTP id 76DC1BEC012 for ; Mon, 18 Jan 2010 05:29:22 +0800 (WST) Message-ID: From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Inclined Radiators Date: Mon, 18 Jan 2010 07:29:20 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_008B_01CA980F.F35473D0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Antivirus: avast! (VPS 100117-1, 01/17/2010), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_008B_01CA980F.F35473D0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Al,=20 Point taken on flow testing. Tracy's duct seems to me to be a = combination of wedge and bell considering his use of roof ridge vent = material at the far end of the duct, as well you both had problems of = distribution because of the far end of the duct, which suggests that a = true wedge at the far end might be more appropriate. Seems counter = intuitive to me and you both it would seem. Might be, at the closer end = the air needs to turn more to enter the Rad and the far end needs to be = thinner to create enough pressure in the duct to make the air turn - = that now makes sense to me. George (down under) Good points & good pictures Al. I'd call your duct a curved bell. = Mine was even more distorted (pix of the mold form attached). The flow = distribution in mine was intended to be controlled by the contours of = the duct and that was mostly successful. It needed to be even thinner = than it is at the back and sides. The correct contour just didn't look = right when I was making it so I didn't pinch it down enough. I have a = temporary fix in place near the back consisting of some roof ridge vent = material to restrict the flow there and raise the pressure further = forward. Turning vanes would be a better fix (but more work). I'm = getting lazy. Tracy On Sun, Jan 17, 2010 at 10:51 AM, Al Gietzen = wrote: As I recall the article, they were measuring the angle from a line = perpendicular to the duct centerline; to the face of the core. There=92s a whole =91nuther factor to consider when shaping the duct = and placing a radiator at an angle; and that is the flow distribution = through the core. For maximum effectiveness, you want the distribution = to be at least fairly uniform so ever part of the core is doing an = effective job. Based on flow measurements that I have done, any time = you=92re expecting the air to turn, it=92s a good idea to do some flow = tests to see if you need to add turning vanes. When I designed the scoop for my main radiator, I chose to try and = follow a K&W profile, but it had to turn nearly 90o and be a bit = shortened (Photo 1). Then I rigged a flow test, and found the flow = velocity was much higher through the far end of the rad than the forward = end. I then did some trial and error placement of a couple turning = vanes (photo 2) until the flow was very uniform. Doing flow tests on the = rads and oil cooler was also allowed measure the pressure drops. Flow testing isn=92t so tough =96 you just need a big centrifugal = blower, some ducting, a small hand-held anemometer, and a water = monometer. And then you have to be inclined to want to do such a thingJ. Al -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of George Lendich Sent: Saturday, January 16, 2010 7:56 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Inclined Radiators was : [FlyRotary] Re: = Scoops Tracy, Ed &Al, I don't know if we are all talking about the same thing so to = clarify in my own mind, I would like to say my opinion on these notes I = have, suggest to me that the 55 degrees, is from the direction of the = air flow i.e. 55 degrees from the horizon or X axis. That would be only = 35 degrees from the Y axis or vertical. So 35 degrees inclined vertical = isn't too bad - in a bell shaped duct. However I could be wrong and the = original reference could have been 55 degrees inclined from vertical, = which also sounds plausible, seeing their talking inclined, one might = think inclined from vertical. Al what's your thoughts on this. However I believe Tracy, you are saying 80 degrees from vertical and = I believe he must be referring to a wedge shaped duct, as I don't think = you could fabricate a bell shaped duct to cope with that degree to the = duct walls. This brings me to the question on what angle is desirable in a wedge = shaped duct, if your unable to fit in a bell shaped duct or should I = merely be considering the size of the inlet opening. I believe I = remember in wedge shaped ducts they should be as high or as wide as the = Rad, considering the placement of rad i.e. under engine or side of cowl = with appropriate depth of the inlet opening. Comments please. George ( down under) =20 Well the basic idea has validity because I carried it to an = extream. My rad is inclined about 80 degrees to the 5" duct so flow = axis is almost perpendicular to the duct. A 5" rad would never cool = that 20B so inclining it radically was the only answer in my = configuration. Water cooling has never been my problem. Oil cooling is = working pretty good with the new oil cooler. It was the "30 row oil = cooler" from CXracing if anyone is curious. Tracy On Sat, Jan 16, 2010 at 4:18 PM, George Lendich = wrote: Ed,=20 I would like to see that again, as I believe would others, like = Al and Thomas. I'm hoping someone tries it in an aircraft to test the = theory. TIA George ( down under) I recall an article on some experiments done on inclined = radiators in race cars.=20 Basically the figures that George mentioned were quoted in the = source. However (big however) what may not have been clearly pointed = out was that the major part of the reason cooling effectiveness (not = efficiency) increased was that inclining the heat exchanger permitted = you to install ever larger area cores in the same size duct. So the = increase in cooling effectiveness by inclination was in large part due = to the larger size radiator permitted by inclined placement in the duct. For example take a duct that is 24=94 wide (X) and 12=94 high = (Y) at zero degree inclination. If you incline the radiator by 30 deg = and then increase its height to again fill the duct,. you can get an = approx 15% increase in the frontal size of the radiator (in the same = 24x12 duct). At 60 deg you could gain approx 100% increase in frontal = size by again increasing the height of the core to fill the duct. . = Naturally that aids in getting rid of the heat. They also point out the = larger core adds weight until you reach a point where the adverse effect = of the heavier radiator core offset its benefit (this was all addressing = their use in race cars). The source indicated that up to 30Deg the drag increases and = heat transfer goes down due to uneven air flow distribution and = disturbances =96 apparently above that angle this adverse effect = decreases and of course you have the much larger frontal area.. At least that is what I recall. If anyone is interested I=92ll = see if I can find the article in my files 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 Al Gietzen Sent: Friday, January 15, 2010 1:13 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Scoops Thomas, Nice research. I found my notes on inclined radiators, they state 1. 0-20/30* will decrease cooling and increase drag. 2. Over 30* things improve. 3. At approx 55* cooling effectiveness is 30% greater than = non-inclined rads=20 and drag is less by 20%. George; do you have the source for that info? It may be a good = idea to verify this information. I don=92t recall the specifics; but = what I do recall is that the conclusion was configuration dependant, and = should not be taken as generally applicable. Sorry, but I don=92t = remember what the factors were; maybe something about the configuration = of the core. Or maybe my memory just isn=92t right. Worth checking. All __________ 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 -------------------------------------------------------------------------= ----- -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_008B_01CA980F.F35473D0 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
 Al, 
Point taken on flow testing. Tracy's = duct seems to=20 me to be a combination of wedge and bell considering his use of roof = ridge vent=20 material at the far end of the duct, as well you both had problems of=20 distribution because of the far end of the duct, which = suggests that a=20 true wedge at the far end might be more appropriate. Seems counter = intuitive to=20 me and you both it would seem. Might be, at the closer end the = air needs to=20 turn more to enter the Rad and the far end needs to be thinner to create = enough=20 pressure in the duct to make the air turn - that now makes sense to = me.
George (down under)
Good=20 points & good pictures Al.  I'd call your duct a curved = bell. =20 Mine was even more distorted (pix of the mold form attached).  = The flow=20 distribution in mine was intended to be controlled by the contours of = the duct=20 and that was mostly successful.  It needed to be even thinner = than it is=20 at the back and sides.  The correct contour just didn't look = right when I=20 was making it so I didn't pinch it down enough.   I have a = temporary fix=20 in place near the back consisting of some roof ridge vent material to = restrict=20 the flow there and raise the pressure further forward.  Turning = vanes=20 would be a better fix (but more work).  I'm getting=20 lazy.

Tracy

On Sun, Jan 17, 2010 at 10:51 AM, Al Gietzen = <ALVentures@cox.net> = wrote:

As I = recall the=20 article, they were measuring the angle from a line perpendicular to = the duct=20 centerline; to the face of the core.

 

There=92s a whole=20 =91nuther factor to consider when shaping the duct and placing a = radiator at=20 an angle; and that is the flow distribution through the core.  = For=20 maximum effectiveness, you want the distribution to be at least = fairly=20 uniform so ever part of the core is doing an effective job. Based on = flow=20 measurements that I have done, any time you=92re expecting the air = to turn,=20 it=92s a good idea to do some flow tests to see if you need to add = turning=20 vanes.

 

When I = designed=20 the scoop for my main radiator, I chose to try and follow a K&W = profile,=20 but it had to turn nearly 90o and be = a bit=20 shortened (Photo 1). Then I rigged a flow test, and found the flow = velocity=20 was much higher through the far end of the rad than the forward = end.  I=20 then did some trial and error placement of a couple turning vanes = (photo 2)=20 until the flow was very uniform. Doing flow tests on the rads and = oil cooler=20 was also allowed measure the pressure drops.

 

Flow = testing=20 isn=92t so tough =96 you just need a big centrifugal blower, some = ducting, a=20 small hand-held anemometer, and a water monometer. And then you have = to be=20 inclined to want to do such a thingJ.

 

Al

 

-----Original=20 Message-----
From: Rotary=20 motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of George = Lendich
Sent: Saturday, January=20 16, 2010 7:56=20 PM
To: Rotary motors in=20 aircraft
Subject: = [FlyRotary] Re: Inclined Radiators was : [FlyRotary] Re:=20 Scoops

 

Tracy, Ed=20 &Al,

I don't know if we are = all=20 talking about the same thing so to clarify in my own mind,  I = would=20 like to say my opinion on these notes I have, suggest to me that the = 55=20 degrees, is from the direction of the air flow i.e. 55 degrees from = the=20 horizon or X axis. That would be only 35 degrees from the Y axis = or =20 vertical. So 35 degrees inclined vertical isn't too bad - in a bell = shaped=20 duct. However I could be wrong and the original reference could have = been 55=20 degrees inclined from vertical, which also sounds plausible, seeing = their=20 talking inclined, one might think inclined from vertical.  Al = what's=20 your thoughts on this.

 

However I believe=20 Tracy, you=20 are saying 80 degrees from vertical and  I believe he must be = referring=20 to a wedge shaped duct, as I don't think you could fabricate a bell = shaped=20 duct to cope with that degree to the duct = walls.

 

This brings me to the = question=20 on what angle is desirable in a wedge shaped duct, if your unable to = fit in=20 a bell shaped duct or should I merely be considering the size of the = inlet=20 opening. I believe I remember in wedge shaped ducts they should be = as high=20 or as wide as the Rad, considering the placement of rad = i.e. under=20 engine or side of cowl with appropriate depth of the inlet=20 opening.

Comments=20 please.

George ( down=20 under)  

 

Well the basic=20 idea has validity because I carried it to an extream.  My rad = is=20 inclined about 80 degrees to the 5" duct so flow axis is almost=20 perpendicular to the duct.  A 5" rad would never cool that = 20B so=20 inclining it radically was the only answer in my = configuration. =20 Water cooling has never been my problem.  Oil cooling is = working=20 pretty good with the new oil cooler.  It was the "30 row oil = cooler"=20 from CXracing if anyone is curious.

Tracy

On Sat, Jan = 16, 2010 at=20 4:18 PM, George Lendich <lendich@aanet.com.au> wrote:

Ed,=20

I = would like to=20 see that again, as I believe would others,  like Al and = Thomas. I'm=20 hoping someone tries it in an aircraft to test the=20 theory.

TIA

George ( down=20 under)

I = recall an=20 article on some experiments done on inclined radiators in race = cars.=20

 

Basically the=20 figures that George mentioned were quoted in the source.  = However=20 (big however) what may not have been clearly pointed out was = that the=20 major part of the reason cooling effectiveness (not efficiency)=20 increased was that inclining the heat exchanger permitted you to = install=20 ever larger area cores in the same size duct.  So the = increase in=20 cooling effectiveness by inclination was in large part due to = the larger=20 size radiator permitted by inclined placement in the=20 duct.

 

For = example=20 take a duct that is 24=94 wide (X) and 12=94 high (Y) at zero = degree=20 inclination.  If you incline the radiator by 30 deg and = then=20 increase its height to again fill the duct,. you can get an = approx 15%=20 increase in the frontal size of the radiator (in the same 24x12=20 duct).  At 60 deg you could gain approx 100% increase in = frontal=20 size by again increasing the height of the core to fill the = duct. =20 . Naturally that aids in getting rid of the heat.  They = also point=20 out the larger core adds weight until you reach a point where = the=20 adverse effect of the heavier radiator core offset its benefit = (this was=20 all addressing their use in race cars).

 

The = source=20 indicated that up to 30Deg the drag increases and heat transfer = goes=20 down due to uneven air flow distribution and disturbances =96 = apparently=20 above that angle this adverse effect decreases and of course you = have=20 the much larger frontal area..

 

At = least that=20 is what I recall.  If anyone is interested I=92ll see if I = can find=20 the article in my files

 

Ed

Ed=20 Anderson

Rv-6A=20 N494BW Rotary Powered

Matthews,=20 NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html<= /P>

http://www.flyrotary.com/

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

http://www.rotaryaviation.com/Rotorhead%20Truth.htm

From:=20 Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Al = Gietzen
Sent: Friday, January = 15,=20 2010 = 1:13 = AM
To: Rotary motors in=20 aircraft
Subject:=20 [FlyRotary] Re: Scoops

 

 

Thomas,

Nice=20 research.

I found my notes = on=20 inclined radiators, they state

1. 0-20/30* will = decrease=20 cooling and increase drag.

2. Over 30* = things=20 improve.

3. At approx 55* = cooling=20 effectiveness is 30% greater than non-inclined rads =

and drag is less = by=20 20%.

 

George; do=20 you have the source for that info? It may be a good idea to = verify this=20 information.  I don=92t recall the specifics; but what I do = recall is=20 that the conclusion was configuration dependant, and should not = be taken=20 as generally applicable.  Sorry, but I don=92t remember = what the=20 factors were; maybe something about the configuration of the=20 core.

Or = maybe my=20 memory just isn=92t right.  Worth = checking.

All



__________ Information from = ESET NOD32=20 Antivirus, version of virus signature database 3267 (20080714)=20 __________

The message was checked by ESET NOD32=20 Antivirus.

http://www.eset.com

 


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