Pic from yesterday

[snowracer69]

Wind tunnel project I'm working on...



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[Mike Ellis]

Give us some details, is that the result of green laser scanning the eddies over a wing leading edge or a pylon in the wind tunnel? Thought you might be using a laser due to the saturation of color in the image.



What kind of flow regime - subsonic?



And most importantly, where the heck are the AirTabs???

 

[HoleshotHolset]

Cool!



About all I did in college was make videos and record/mix music...



Matt

 

[snowracer69]

Added the middle image to explain this...



We're trying to improve the high angle-of-attack characteristics of a super-critical airfoil (what most airliners use, especially Boeing... we actually tried to model it after the 777). The fluid is just UV dye mixed in transmission fluid (won't flow as fast that way) and put under a black light. Pics range from I believe 5* aoa to 17. 5*. Stall actually occurs between pics 2 and 3. If anyone wants one for a desktop I can email bigger pics.



We really didn't come up with anything today. Today was mostly about trying to find out where the flow would start seperating (which you can see in the second pic above, at the rear of the wing, where it starts to bubble and reverse it's flow) and where it actually stalls out. We figure out where it stalls from force measurements and look for the seperation and other factors using the flow-viz stuff.



The test we're actually doing is to put a "wing fence" at 45% of the span to stop the outward flow down the wing (which you can also see in the second pic, w/ the lines heading towards the top) and also we're going to put "vortex generators" on the wing to try and energize the boundary layer right next to the wing so it'll stay attached longer at higher aoa's.



Basically, we're not trying to come up with anything new, just prove how/why stuff works. The class is mostly about learning how to take and interpret data... useable results don't really mean anything. Pretty pictures are a bonus though!



Oh, and in the first pic you can clearly see the transition from laminar (Smooth streamlines) flow to turbulent flow... it occurs at the obvious line that is just back from the leading edge. I believe the airfoil we used is a NACA-64012. The wing is built from a solid piece of mahogoney with about 40 hours of one of my partenrs and my sweat in it... . lot more work building it than we expected.



And yes, it's subsonic, probably around 125-150 ft/s.



Josh

 

[klenger]

Cool pics. If you can make it fly, I can get it to navigate