Different results between old and new WT_perf

Wind & Water Computer-Aided Engineering Software Tools
1

Hello everyone:
I downloaded new WT_perf v.3.05.00a (09-November-2012), and i compared it with old version 3.10 (02-July-2004)
I compared the same CertTest file “Test05_WL8” but the results are different.
By analyzing .bed and .ech files, it seems that new WT_perf loads all airfoil-table but it uses only the first Re number.
Old and new airfoil-table differ only for “control setting” line; all lift and drug coefficient are the same. isn’t it?

What do you think about?
Did i do something wrong?

Thanks.
Best regards.
Gabriele Gambaretto

2

Hi Gambaretto,

I’m just now getting caught up with the forum after being away for over two weeks. I don’t have a quick answer for you, but I’ve added your issue to my list of things to worry about. I’m not sure when I will get to it.

One thing I would like to say is that the algorithm for iterating to a converged solution has been changed completely since 2004. The new version is more robust and we are working on an even better one that will be used for both WT_Perf and AeroDyn. If the problem is with interpolating the airfoil data, we’ll definitely have to tackle that.

Marshall

3

Dear Gabrielle and Marshall,

Please check GetAFTI subroutine in WTP_Subs.f90 as it seems that local variable Re has been declared but it never gets computed inside the subroutine.

Best regards,
Dragan

4

Dear Dragan,

I think you are right.
“SUBROUTINE GetCoefs” needs of local Re to compute local airfoil coefficients.
In this case it seems that the software used Re=0 and it satisfied the next command line

IF ( Re <= AF_Table%Tab(1)%Re ) THEN
ITabLo = 1
OneTable = .TRUE.

thank you for your research
i hope Marshall can check this problem in the next months

Best regards,
Gabriele

5

Dear Gabrielle and Marshall,

I hope that you can verify that solution to the problem would be just to add the line:

Re=VInd*Chord(Iseg)*RotorRad/KinVisc

in GEtAFTI subroutine just before the IF block (Line 1750) and two calls to GetCoefs routine.

Hopefully the code would run without problems and it would be safe in sense of any unwanted interactions with the rest of the code and other variables.

Best regards,
Dragan

6

Folks,

I’ve been distracted by other critical projects recently and have not have time to even read the forums–much less fix anything. I’m still in the middle of something, but I’ll try to fix this sometime soon.

I apologize for taking so long to respond.

Marshall

7

Hi,

There is no money to work on WT_Perf. This will have to wait until at least late in 2014. Sorry.

Marshall