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[70.196.196.50]) by mx.google.com with ESMTPS id ka4sm1117897pbc.61.2012.10.10.07.43.16 (version=TLSv1/SSLv3 cipher=OTHER); Wed, 10 Oct 2012 07:43:18 -0700 (PDT) Subject: Re: [FlyRotary] Re: cooling airflow concepts References: From: Tracy Content-Type: multipart/alternative; boundary=Apple-Mail-608F2EBC-EC9B-4290-A29F-DEE46E4E1BDE X-Mailer: iPad Mail (10A403) In-Reply-To: Message-Id: Date: Wed, 10 Oct 2012 08:43:15 -0600 To: Rotary motors in aircraft Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) --Apple-Mail-608F2EBC-EC9B-4290-A29F-DEE46E4E1BDE Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Steve, in the last iteration of my inlets, the water side is larger than 5 1= /4. Slightly less than 6" but can't recall the exact number now. Too far= away to measure. I think the Oil cooler inlet is now 5 1/4". =20 Tracy Sent from my iPad On Oct 9, 2012, at 6:39 PM, Stephen Izett wrote: > Thanks again Steve >=20 > My current snout looks similar to the attached image. > I'm considering going to the trouble of reworking the cowl into two circul= ar duct openings, keeping them as far from the centre of the prop as possibl= e. > Current opening is approx 7'' x 3'' - 21sqin. > Tracy I believe uses (Water Side) 5 1/4" so - 21sqin. > Multiply Tracy's by 2/3 (loose a rotor) + a bit for the extra side exhaust= energy (Renesis) going into the coolant - say 15sqin's or 4 1/2 inch diamet= er. > The other attached photos are modified Glasair snouts > What do you think I should consider given the amount of work involved and t= he possible improvement factored in? >=20 > Cheers > Steve Izett=20 > > > . > <9m.JPG> > =20 >=20 >=20 > On 09/10/2012, at 11:08 PM, Steven W. Boese wrote: >=20 >> Steve, >> =20 >> Specific details concerning Tracy's cooling setup and performance are bes= t obtained directly from him. >> =20 >> I can try to relate my take on the concepts that were discussed, though: >> =20 >> The area, cross sectional shape, location as far as practical from the ce= nter of the prop, and the location close behind the prop have combined to gi= ve good inlet characteristics under a wide range of conditions of airspeed a= nd angle of attack. >> =20 >> The construction of the diffuser should result in smooth walls and avoid s= udden changes in direction of the air flowing within it. Divergence angles g= reater than 7 degrees are not necessarily a pressure recovery killer. >> =20 >> Other than the exact inlet cross sectional shape and area, the concepts j= ust mentioned follow largely from common sense. >> =20 >> The concept that was surprising to me was that a large change in directio= n of air flow from the diffuser into the core right at the face of the core i= s not necessarily a bad thing. Since the flow of the air through the core i= s intended to be turbulent, the turbulence resulting from the rapid directio= n change at the core face may actually be a good thing. In Tracy's coolant e= xchanger arrangement, the core is almost at a right angle to the direction o= f air flow within most of the diffuser. The critical part appears to be the= shape of the interface between the core and the diffuser with the diffuser w= all distance from the core becoming very small at the downstream end. The g= oal is to provide consistent pressure across the whole face of the core and t= hus get uniform airflow through the whole core. Achieving this goal will pr= obably involve some experimentation and changes in the diffuser to core tran= sition shape for a particular installation. Making measurements of airflow t= hrough different parts of the core would be essential to asses the effect of= changes made. Although this all sounds daunting, the freedom resulting fro= m the ability to change the direction of airflow at the core face may allow g= reater emphasis on the construction of a diffuser with good pressure recover= y within the constraints of the under cowl space available. >> =20 >> That's just my interpretation of what I thought I heard. Someone please c= orrect me if I am mistaken. >> =20 >> Steve Boese >> RV6A, 1986 13B NA, RD1A, EC2 >> =20 >> =20 >> =20 >> =20 >> =20 >> From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf o= f Stephen Izett [steveizett@me.com] >> Sent: Monday, October 08, 2012 6:17 PM >> To: Rotary motors in aircraft >> Subject: [FlyRotary] Re: Rotorfest 2012 photos >>=20 >> Hi Steve >>=20 >> Thanks for the report from the flyin, always good to get feedback and pho= tos. >> Wish I could get to see some of the flying examples. Bit tricky being dow= n under. >> I've modelled my (Glasair SIIRG Renesis 4 port) cooling of Tracy's 8. Was= there any thoughts - pros and cons, improvements of his setup. >> It would seem to be functioning very well. >> He has spoken previously of the importance of the diffuser shape (I am ye= t to build it so am interested in his thoughts) and the difference his newer= inlets made. >>=20 >> Much appreciated >>=20 >> Steve Izett >> Perth Western Australia=20 >=20 --Apple-Mail-608F2EBC-EC9B-4290-A29F-DEE46E4E1BDE Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Steve,  in the last iteration of m= y inlets, the water side is larger than 5 1/4.  Slightly less than 6" &= nbsp;but can't recall the exact number now.   Too far away to measure. &= nbsp;I think the Oil cooler inlet is now 5 1/4".  

=
Tracy

Sent from my iPad

On Oct 9, 2012, at 6:39 PM= , Stephen Izett <steveizett@me.com> wrote:

=


On 09/10/2012, at 11:08 P= M, Steven W. Boese wrote:

Steve,

=  

Specific deta= ils concerning Tracy's cooling setup and performance are best obtained d= irectly from him.

&n= bsp;

I can try to re= late my take on the concepts that were discussed, though:

 

The area, cross sectional shape, location as far as=  practical from the center of the prop, and the location close behind t= he prop have combined to give good inlet characteristics under a wide range o= f conditions of airspeed and angle of attack.

 

 

Other than the exact inlet c= ross sectional shape and area, the concepts just mentioned follow largely fr= om common sense.

&nb= sp;

The concept that= was surprising to me was that a large change in direction of air flow from t= he diffuser into the core right at the face of the core is not necessar= ily a bad thing.&nb= sp; Since the flow of the air through the core is intended to be turbulent, t= he turbulence resulting from the rapid direction change at the core face may= actually be a good thing.  In Tracy's coolant exchanger arrangement, t= he core is almost at a right angle to the direction of air flow within most o= f the diffuser.  The critical part appears to be the shape of the inter= face between the core and the diffuser with the diffuser wall distance from t= he core becoming very small at the downstream end.  The goal is to prov= ide consistent pressure across the whole face of the core and thus get unifo= rm airflow through the whole core.  Achieving this goal will probably i= nvolve some experimentation and changes in the diffuser to core tr= ansition shape for a particular installation.  Making measurements= of airflow through different parts of the core would be essential= to asses the effect of changes made.  Although this all sounds da= unting, the freedom resulting from the ability to change the direction&= nbsp;of airflow at the core face may allow greater emphasis on the construct= ion of a diffuser with good pressure recovery within the constraints of the u= nder cowl space available.

 

That's j= ust my interpretation of what I thought I heard.  Someone please correc= t me if I am mistaken.

Steve Bo= ese
RV6A, 1986 13B NA, RD1A, EC2

 

 

 

 

 

From:=  Rotary motors in airc= raft [flyrotary@lancaironline= .net] on behalf of Stephen Izett [s= teveizett@me.com]
Sent:&= nbsp;Monday, October 08, 2012 6:17 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Rotorfes= t 2012 photos

Hi Steve

Thanks for the report from the flyin, always good to get feedback and phot= os.
Wish I could get to see some of the flying examples. Bit trick= y being down under.
I've modelled my (Glasair SIIRG Renesis 4 port= ) cooling of Tracy's 8. Was there any thoughts - pros and cons, improvements= of his setup.
It would seem to be functioning very well.
He has spoken previously of the importance of the diffuser shape (I am yet= to build it so am interested in his thoughts) and the difference his newer i= nlets made.

Much appreciated

Steve Izett
Perth Western Australia 

<= div>

 
= --Apple-Mail-608F2EBC-EC9B-4290-A29F-DEE46E4E1BDE--