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Cylinder Baffles

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Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Mon Feb 29, 2016 9:05 pm Post subject: Cylinder Baffles

Hi Gary, 

The baffles you developed and got approved are very well done. I think they are resposible for a lot of the cooling improvement my Tiger has. I've been doing some reading lately and found a couple interesting studies that make me want to try a change to the baffles under the cylinder heads where the air exits. I'd like to try extending the curved down portion of the baffle by an inch or two. See Picture Below.

I was interested in Your opinion.



Two of the articles I was reading are:

http://www.dtic.mil/dtic/tr/fulltext/u2/a800800.pdf

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930081408.pdf

Regards, 

Ned

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Posted: Thu Mar 03, 2016 10:34 am Post subject: Cylinder Baffles

First of all, Hi.  How are you and Gina doing?  Well, I hope.



1.  The drawings you provided have nothing to do with our engines.  

2. There is no flat surface on top to make curved to do what the drawing shows.

3. You can do all you want with the bottom of the baffles.  It’s your time and your money.  You won’t see a significant change.

4. Do you have cooling problems?



What you want is pressure drop across the cylinders.  That creates the flow of air.  The baffles for the Jaguar cowling are the result of a lot of trial and error on stock baffles.  



I’d love to hear about your results of modifying the baffles.  



Gary

 	  Quote: 	
		   On Feb 29, 2016, at 9:05 PM, Discover <923te(at)att.net> wrote:

 

 

 

 The baffles you developed and got approved are very well done. I think they are resposible for a lot of the cooling improvement my Tiger has. I've been doing some reading lately and found a couple interesting studies that make me want to try a change to the baffles under the cylinder heads where the air exits. I'd like to try extending the curved down portion of the baffle by an inch or two. See Picture Below.

 I was interested in Your opinion.

 

 Two of the articles I was reading are:

 http://www.dtic.mil/dtic/tr/fulltext/u2/a800800.pdf

 http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930081408.pdf

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=453324#453324

 

 

 

 

 Attachments: 

 

 http://forums.matronics.com//files/image_861.jpeg

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Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Thu Mar 03, 2016 8:46 pm Post subject: Re: Cylinder Baffles

The articles are in depth studies of cylinders from the radial engine of 1930's vintage. They are very much like ours as you can see from the photos within the articles. 



The conclusions are quite interesting and address my interest where it says:

CONCLUSIONS 

1. A 20-percent increase in cooling was obtained by the use of a properly designed baffle exit. This gain corresponds to that which can be obtained when the standard baffle with a 65-percent increase in pressure drop across the baffle is used. 



2. The baffle-exit radius and width and exit-duct 

length were found to be the most critical parts of the 

baffle.



And from this article

http://www.dtic.mil/dtic/tr/fulltext/u2/b807149.pdf

"For the best arrangement tested in reference 8, 36 percent of the total pressure drop across the cylinder was shown to take place in the fins, 50 percent at the baffle exit, and 14 percent at the exit from the exit duct. Only the pressure drop that occurred in the fins was useful in cooling the cylinder. On many modern engines, the useful pressure drop is only about 20 percent of the total drop."



This along with the other articles findings seem to be telling me there may even be more significant improvement possible than we have gotten with the new baffles.  



The baffles that came with my Jaguar cowl are a vast improvement over the factory baffles even when the factory baffles are brand new. I have recommended them to several people. It is only my experimenter /racing demands that is at work here coupled with my engineering mind that is asking along the lines of a quote I first learned of from Gary's AUCountry website,

that cause me to continue to pursue and ask the question...

"Never leave well enough alone." Ramond Loewy



The air exiting the cylinders and heads must make a 90 degree turn and that is cause for a big loss of energy. This concept was recently pointed out to me in a discussion of the Tiger air box compared to the AG5B airbox. Turns out that there are several 90 degree turns with air in our Tigers...

Best,

Ned

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Last edited by Discover on Thu Mar 03, 2016 9:14 pm; edited 1 time in total

Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Thu Mar 03, 2016 8:57 pm Post subject: Re: Cylinder Baffles

If you think that adding diffusers to the air exits on the bottom of the heads and cylinders is just too far out there then try looking at it after seeing the extreme this guy went to improve cooling drag...

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Posted: Fri Mar 04, 2016 10:41 am Post subject: Cylinder Baffles

what about the added weight?

 	  Quote: 	
		   On Mar 3, 2016, at 8:57 PM, Discover <923te(at)att.net> wrote:

 

 

 

 If you think that adding diffusers to the air exits on the bottom of the heads and cylinders is just too far out there then try looking at it after seeing the extreme this guy went to improve cooling drag...

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=453405#453405

 

 

 

 

 Attachments: 

 

 http://forums.matronics.com//files/image_116.jpeg

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