X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 6.0c1) with ESMTP id 5732125 for flyrotary@lancaironline.net; Tue, 28 Aug 2012 08:27:22 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=eanderson@carolina.rr.com Return-Path: X-Authority-Analysis: v=2.0 cv=QrvcLCOd c=1 sm=0 a=g3L/TDsr+eNLfIieSKfGkw==:17 a=AHkS0RJitIMA:10 a=Dsx-g_URPcMA:10 a=05ChyHeVI94A:10 a=ib9MlSP14YoA:10 a=ayC55rCoAAAA:8 a=S9F906fiAAAA:8 a=Ia-xEzejAAAA:8 a=oCcaPWc0AAAA:8 a=33frofYzfVslbtDPG7QA:9 a=wPNLvfGTeEIA:10 a=EzXvWhQp4_cA:10 a=AbYz9SnhSDqFEdq1:21 a=hqcf4Dy29xBQFt5q:21 a=on22okXAAAAA:8 a=irEETfHLc9CF5jjXlh4A:9 a=UiCQ7L4-1S4A:10 a=_W_S_7VecoQA:10 a=frz4AuCg-hUA:10 a=tXsnliwV7b4A:10 a=at0Q5_2dr5wA:10 a=lps9KRSiZ4cu3DKk:21 a=iO0LesE3wJDAZPiR:21 a=ZHUsY8zHUz0Vp2Os_2YA:9 a=1Vq_FK4TplAA:10 a=g3L/TDsr+eNLfIieSKfGkw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 174.110.170.10 Received: from [174.110.170.10] ([174.110.170.10:49461] helo=EdPC) by cdptpa-oedge04.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 35/AA-28917-709BC305; Tue, 28 Aug 2012 12:26:47 +0000 Message-ID: From: "Ed Anderson" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Spreadsheet Cooling Section Date: Tue, 28 Aug 2012 08:26:48 -0400 MIME-Version: 1.0 Content-Type: multipart/related; type="multipart/alternative"; boundary="----=_NextPart_000_0009_01CD84F6.DE3F6410" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8117.416 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416 This is a multi-part message in MIME format. ------=_NextPart_000_0009_01CD84F6.DE3F6410 Content-Type: multipart/alternative; boundary="----=_NextPart_001_000A_01CD84F6.DE3F6410" ------=_NextPart_001_000A_01CD84F6.DE3F6410 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I understand, Jeff. The equations are seldom the problem, the problem = is how to apply them and the initial conditions. I'll check out the = link and see what I can gleen from it. Ok, read the paper. Basically it's the same equations I am using (basic = heat transfer equation). The difference is they derive DT from DT =3D = coolant Temp - Ambient Temp rather than the unilateral choice I made of = DT =3D 70F. What might be useful would be the equation for the curve = for the non-linear curve showing cfm airflow required vs DT. I will look into it some more and see what makes sense. Thanks Ed From: Jeff Whaley=20 Sent: Tuesday, August 28, 2012 8:06 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Spreadsheet Cooling Section Ed, I don't claim to know how to the fix the equations, was just = pointing out what I encountered when using the spreadsheet. The following link provides some equations and graphs for the effects of = OAT on required airflow; it's mostly about designing with fans but = principle is the same. http://www.flexxaire.com/documentation/modern_cooling_system_theory.pdf I think your initial thoughts of picking a mid-point temperature then = apply the DT above/below that point will help the cooling section - HP = section looks very good! Jeff : "Ed Anderson" =20 Subject: Re: [FlyRotary] Re: [flyRotary] Spreadsheet Cooling = Section =20 Date: Fri, 24 Aug 2012 18:48:53 -0400 =20 To: "Rotary motors in aircraft" = =20 =20 =20 =20 No doubt it could stand improvements for sure, Jeff. There are four DT's I employ in the cooling equations. Change = in air temperature across the radiator, change in air temperature = across the oil cooler and change in fluid temperature of the coolant and = oil as they flow through their heat exchanger. I have heard of Air DT = across the radiator ranging from 50-100F, I am currently using a DT of = 70F , but I know that Tracy has reported a DT of 100F. I am also = using DT of 70F for the oil cooler and that is probably too high. For = both fluid DTs, I am using 16F. IF anyone has reference material or sources that could help me = refine those figures - it would undoubtedly improve the cooling section. As Jeff pointed out for the cooling section there is no input for = OAT although there is for the power section. My initial thoughts would = be to pick=20 some OAT and I'm thinking of 59F (SL standard day temp) as a = nominal mid point of DT. Then if OAT is above that DT, then to simply = subtract the difference between OAT and 59F and reduce the air DT across = the radiator by that amount. Conversely if OAT is below 59F then to add = that DT to the 70F I am currently using.=20 By increasing the DT factor more heat is transferred (better = cooling) by reducing the DT factor less heat is transferred (worst = cooling) IF anyone has reference material or sources that could help me = refine those figures - it would undoubtedly improve the cooling section. Ed Edward L. Anderson Anderson Electronic Enterprises LLC 305 Reefton Road Weddington, NC 28104 =20 This message, and the documents attached hereto, is intended only for = the addressee and may contain privileged or confidential information. = Any unauthorized disclosure is strictly prohibited. If you have received = this message in error, please notify us immediately so that we may = correct our internal records. Please then delete the original message. = Thank you.=20 No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2197 / Virus Database: 2437/5227 - Release Date: = 08/27/12 ------=_NextPart_001_000A_01CD84F6.DE3F6410 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I understand, Jeff.   The equations = are seldom=20 the problem, the problem is how to apply them and the initial = conditions. =20 I'll check out the link and see what I can gleen from it.
 
Ok, read the paper.  Basically it's the = same=20 equations I am using (basic heat transfer equation).  The = difference is=20 they derive DT from DT =3D=20 coolant Temp - Ambient Temp rather than the unilateral choice I made of = DT =3D 70F.    What might be useful = would be the=20 equation for the curve for the non-linear curve showing cfm airflow = required vs DT.
 
I will look into it some more and see what makes = sense.
 
 
Thanks
 
Ed

Sent: Tuesday, August 28, 2012 8:06 AM
Subject: [FlyRotary] Re: Spreadsheet Cooling=20 Section

Ed, I don=92t claim to know how to the fix the = equations, was=20 just pointing out what I encountered when using the spreadsheet.

The following link provides some equations and = graphs for the=20 effects of OAT on required airflow; it=92s mostly about designing with = fans but=20 principle is the same.

http://www.flexxaire.com/documentation/modern_cooling_system_theo= ry.pdf

I think your initial thoughts of picking a = mid-point=20 temperature then apply the DT = above/below=20 that point will help the cooling section =96 HP section looks very = good!

Jeff

 

:

"Ed=20 Anderson" = <eanderson@carolina.rr.com>

Subject:

Re:=20 [FlyRotary] Re: [flyRotary] Spreadsheet Cooling=20 Section

Date:

Fri,=20 24 Aug 2012 18:48:53 -0400

To:

"Rotary=20 motors in aircraft"=20 = <flyrotary@lancaironline.net>

<= /TD>



No = doubt it=20 could stand improvements for sure, Jeff.

 

  = There are=20 four DT's I = employ in=20 the cooling equations.  Change in  air temperature = across the=20 radiator, change in air temperature across the oil cooler and = change in=20 fluid temperature of the coolant and oil as they flow through = their=20 heat exchanger.    I have heard of Air = DT = across the=20 radiator ranging from 50-100F,  I am currently using a=20 DT of = 70F ,=20 but I know that Tracy has reported a DT = of =20 100F.   I am also using DT of = 70F for the=20 oil cooler and that is probably too high.   =  For both=20 fluid DTs, I = am using=20 16F.

 

IF = anyone has=20 reference material or sources that could help me refine those = figures - it=20 would undoubtedly improve the cooling section.

 

As = Jeff pointed=20 out for the cooling section there is no input for OAT although = there is=20 for the power section.  My initial thoughts would be to pick=20

 

some OAT and=20 I'm thinking of 59F (SL standard day temp) as a nominal mid point=20 of =20 DT.  Then if=20 OAT is above that DT, = then to=20 simply subtract the difference between OAT and 59F and reduce the = air=20 DT = across the=20 radiator by that amount.  Conversely if OAT is below 59F then = to add=20 that DT to=20 the 70F I am currently using. 

 

By = increasing=20 the DT = factor more=20 heat is transferred (better cooling) by reducing the = DT = factor less=20 heat is transferred (worst cooling)

 

IF = anyone has=20 reference material or sources that could help me refine those = figures - it=20 would undoubtedly improve the cooling section.


Ed

 

Edward = L.=20 Anderson
Anderson Electronic Enterprises LLC
305 Reefton=20 Road
Weddington, NC 28104

 

This message, and the documents = attached=20 hereto, is intended only for the addressee and may contain privileged or = confidential information. Any unauthorized disclosure is strictly = prohibited. If=20 you have received this message in error, please notify us immediately so = that we=20 may correct our internal records. Please then delete the original = message. Thank=20 you.

No virus found in this=20 message.
Checked by AVG - www.avg.com
Version: 2012.0.2197 / = Virus=20 Database: 2437/5227 - Release Date: 08/27/12

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