Polars and Reynold’s number  
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Polars and Reynold’s number - 7/2/2003 7:20:04 PM   
yclui


 

Posts: 43
Joined: 10/13/2002
From: Hongkong,
Status: offline 		Hello,

I would like to get some understanding on how the polars of airfoils change with Reynold’s number. May I know whether there are any internet resources on this subject ?

Thanks,

Y C Lui
       Post #: 1

Polars and Reynold’s number - 7/2/2003 10:36:19 PM   
Montague



Posts: 4653
Joined: 4/19/2002
From: Laurel, MD,
Status: offline 		"depends on the airfoil"

Get Profili (what I use) or other airfoil analysis software, and play around with it and see. Re can be a huge factor for some airfoils, less of one for others.


_____________________________

Kirk Montague Adams
RCCA 560

(in reply to yclui)
       Post #: 2

Re: Polars and Reynold’s number - 7/3/2003 6:59:41 AM   
PhatVu


 

Posts: 10
Joined: 5/7/2003
From: Huntington Beach, CA,
Status: offline 		A good web site is:
http://www.mh-aerotools.de/airfoils/foil_gliders.htm

These airfoil data should show the drag polar with respect to different Re. I downloaded "Xfoil", a free airfoil analysis software developed by Dr. Drela. You can get more info about Xfoil here:
http://groups.yahoo.com/group/xfoil/

There is a learning curve for the Xfoil program. I would just use the example files in the download and start from there. Since most people have super-fast PCs, I would bump up the iteration value to make the analysis faster. You will find out. The Profili software mentioned by Montague has also integrated Xfoil into its software suite. So using Xfoil is much easier that way but you have to pay a nominal license fee. I always prefer the "free" product.

Phat Vu


[QUOTE]Originally posted by yclui
Hello,

I would like to get some understanding on how the polars of airfoils change with Reynold’s number. May I know whether there are any internet resources on this subject ?

Thanks,

Y C Lui [/QUOTE]

(in reply to yclui)
       Post #: 3

Polars and Reynold’s number - 7/3/2003 11:07:08 AM   
yclui


 

Posts: 43
Joined: 10/13/2002
From: Hongkong,
Status: offline 		Many Thanks to Kirk and Phat ! May I know where I can get Profili ?

(in reply to yclui)
       Post #: 4

Polars and Reynold’s number - 7/3/2003 5:51:52 PM   
Oryx


 

Posts: 198
Joined: 6/17/2002
From: Pretoria, SOUTH AFRICA
Status: offline 		[QUOTE]Originally posted by yclui
Many Thanks to Kirk and Phat ! May I know where I can get Profili ? [/QUOTE]

http://www.profili2.com/

Stefano only asks $10 for registering the program (you can get an evaluation copy with some features locked out for free). I think it is a bargain, considering the amount of time that went into writing a program such as that. Profili is basically a user friendly interface to XFOIL. I still use XFOIL directly for some purposes (in my research), but Profili certainly makes it much easier to get started, and it has a very good database of airfoils and pre-analyzed polars. If you are interested in aerodynamics at all, I think it is more than worth it.

(in reply to yclui)
       Post #: 5

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