| T O P I C R E V I E W |
| gotwind |
Posted - 30/03/2008 : 12:36:15
Might be worth a try on a set of PVC blades...
http://www.gizmag.com/bumpy-whale-fins-set-to-spark-a-revolution-in-aerodynamics/9020/
The Futures Green - Getwind of it. |
| 6 L A T E S T R E P L I E S (Newest First) |
| gholt |
Posted - 01/04/2008 : 05:19:36
An explanation of the vortex function:
http://www.aircraftspruce.com/pdf/2008Individual/Cat08190.pdf
As applied to propellers:
http://www.aircraftspruce.com/catalog/appages/vortelator_kit.php
G. |
| MattM |
Posted - 01/04/2008 : 02:20:41
# = diameter
24" @ 500 rpm = 36 mph
24" @ 750 rpm = 54 mph
24" @ 1000 rpm = 71 mph
36" @ 500 rpm = 54 mph
36" @ 750 rpm = 80 mph
36" @ 1000 rpm = 107 mph
48" @ 500 rpm = 71 mph
48" @ 750 rpm = 107 mph
48" @ 1000 rpm = 143 mph
Someone else can recheck my math... ;)
Go Huskers! |
| gholt |
Posted - 31/03/2008 : 20:01:05
The principles of the "vortex generator" have been studied and applied to low speed aircraft for some time and from appearances at a handsome profit to those in the biz.
http://www.microaero.com/
Making your own vortex generators is pretty straight forward with pliers and thin sheet aluminum. From my limited understanding they don't offer much assistance in high speed applications however. Low speed refers to aircraft flying in the 40-80 mph range ... how fast is the tip speed of that set of blades turning at 500-1,000 RPM on a 24-48 inch [610mm - 1220mm] diameter prop? Or are we talking efficient kite flying ?
G. |
| BushWhacker |
Posted - 31/03/2008 : 05:45:31
I brought this up some time ago...
http://gotwind.forumco.com/topic~TOPIC_ID~180~SearchTerms~,blades.asp
Interesting concept though.
Everything should be made as simple as possible, but not one bit simpler. - Albert Einstein |
| MattM |
Posted - 30/03/2008 : 14:25:47
Key points:
* "It seems despite man's endless ingenuity and the incredible modeling power available to inventors through CAD systems, we keep looking to nature to find ever more effective ways of doing things."
* "Turbines fitted with tubercles to the leading edges of each blade are able to produce more power at low fluid speeds, are quieter, and perform much better in turbulent fluid streams."
* "It seems the bumps have the effect of channeling air into smaller areas of the blade, resulting in a higher wind speed through the channels and a number of rotating airflows on top of the blade which increase lift."
* "Furthermore, the bumps eliminate the tendency of air to run down the length of the blade's edge and fly off at the tip, causing noise, instability and a loss of efficiency."
* "After discovering the Tubercle effect, Fish worked with Phil Watts to invent and patent a new type of leading edge for airfoils and hydrofoils."
I don't get how they can patent something like this when mother nature owns prior art. Just seems so wrong to allow patents on this idea. You could easily make channels on your pvc blades using pl400 glue and a notched scraper, you know the common every day one you'd use to mount tile on the floor or walls.
edit: prior art? http://www.pratt.duke.edu/news/?id=101
Go Huskers! |
| Tim L |
Posted - 30/03/2008 : 13:49:44
Wouldn't be at all surprised. Nature has had millions of years to try everything, no matter how nuts it looks to us. Our own vaunted finite element analysis and CAD-CAM systems can optimise things to hellandgone but it's all reliant on their basic mathematical assumptions built into the computer models of aero- and hydrodynamics being 100% accurate. |
