Multi-element fowler airfoil modelling

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arj1

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Hi, not sure if it was answered here, but is there any free tools that can assess CL, CM and CD of a multi-element Fowler airfoil and close to reality? The only one I know is OpenFoam. I've been told that Java Foil is not that accurate and rather, should I say, optimistic in determining lift at maximum AoA. 2D initially should OK. Thanks!
 

arj1

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Hi! "Enjoy the silence..."
Sorry, have I posted that in the right forum area?
Or is it that the question is wrong?
Thanks!
 

Aerowerx

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XFLR5???

Set it up with tandem wings closely spaced???

Don't know if it will work but you might look into it. XFLR5 works ok if you aren't too far into the Twilight Zone. Otherwise it can get a bit weird on you.

But remember it is a mathematical simulation, not reality.

BTW, you shouldn't expect instant answers. It can take a few days before someone with enough interest answers a post.
 

Aerowerx

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One further comment...

If you decide to try XFLR5 it can be quite intimidating at first, but once you figure it out it isn't that difficult.
 

ypsilon

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What exactly are you trying to achieve? Do you have an actual configuration in mind?
A good combination of high-lift devices (droop-nose/ slats/ slotted flaps etc), can get you cl-values well above 3. However they introduce all kinds of mechanical (aeroelastic) problems.
 

arj1

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What exactly are you trying to achieve? Do you have an actual configuration in mind?
A good combination of high-lift devices (droop-nose/ slats/ slotted flaps etc), can get you cl-values well above 3. However they introduce all kinds of mechanical (aeroelastic) problems.
Well, GA(W)-2 is 3.8 with just two elements (that is from NASA paper, experiment - 1.7 for flaps up, 3.8+ for flaps extended).
There is a 4 element modification of MDA 30P-30N which achieves 5.0, that is CFD, and NOT experiment data. Read an article somewhere that with five element version of Eppler 1230 even high CL was achieved... Just wanted to validate things like that.
 

ypsilon

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You can have (theoretical) multislot setups beyond a cl of 6.0. If you have blown surfaces even more, but in practice those are not useful since not only the drag increases disproportionately, but also the stall behaviour becomes quite problematic (not to speak of the mechanical challenges you'd face). Modern airliners in full high lift configuration reach about 3.5, which is already quite impressive.

As said 3D cl will be significantly lower than 2D cl, unless you have infinite A/R (which most can't afford).
 

arj1

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You can have (theoretical) multislot setups beyond a cl of 6.0. If you have blown surfaces even more, but in practice those are not useful since not only the drag increases disproportionately, but also the stall behaviour becomes quite problematic (not to speak of the mechanical challenges you'd face). Modern airliners in full high lift configuration reach about 3.5, which is already quite impressive.
Yep, abrupt stall etc... And for airliners - they all have swept wings, so their CL will be at least 0.85 of the max Wing CL.

As said 3D cl will be significantly lower than 2D cl, unless you have infinite A/R (which most can't afford).
That is true! Although on AR>10 it will be less pronounced.
 

Heliano

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ypsilon's question - "what exactly are you trying to achieve?" is important. The aerodynamic quality of a wing depends on several factors, not just the 2D-airfoil.
In some cases it is preferable to reduce wing loading instead of using sophisticated hi-lift devices. And stall propagation along the wing span is perhaps the most critical aspect, safetywise. My humble comment - may be you are well aware of it - is: be careful when you associate GA(W) airfoils with powerful high lift devices. There is no free lunch in aerodynamics: if you use a very efficient, laminar flow airfoil, the wing will be very sensitive to subtle shape changes, gap dimensions, etc. I remember having flown the Piper Tomahawk quite a few years ago (decades ago), which has a GA(W)-1 wing, practiced some stalls and I definitely did not like the aircraft behavior, perhaps due to minor differences in wing manufacturing.
 
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