Questions about Cl,Cd of naca0012

darenyang · May 20, 2009, 08:26

hello all,
i am new on OF1.5,i want to simulate the naca 0012 wing , i have found experimental results in internet http://www.cyberiad.net/foildata.htm , also i found the parameter of the model, the chord length is 15.24cm, span length 0.91m . i have set my controlDict with forces and forceCoeffs. but i get wrong results , i dont know why ,could anyone help me check my functions _??
functions
(
forces
{
type forces;

// Where to load it from (if not already in solver)
functionObjectLibs ("libforces.so");

patches ( wall );
rhoInf 1.0;
CofR (0 0 0);

}

forceCoeffs
{
type forceCoeffs;

// Where to load it from (if not already in solver)
functionObjectLibs ("libforces.so");

patches ( wall );
rhoInf 1.0;
CofR (0 0 0);
liftDir (0 1 0);
dragDir (1 0 0);
pitchAxis (0 0 0);
magUInf 10;
lRef 0.1524;
Aref 0.1387;

}

dani · May 20, 2009, 10:53

Hi!

You can try to set pitchAxis to

pitchAxis (0 0 1);

Other parts seem to be correct.
(To tell you all the truth, I'm not sure of the value of Aref, but I think it's ok.)

dani

cwang5 · May 26, 2009, 08:34

Maybe it's caused by the difference in rho?

I use 1.225 for my calculations...

wikstrom · May 26, 2009, 15:48

Mabe it's caused by a bad solution?

darenyang · June 1, 2009, 05:47

thx for all reply,

i used SimpleFoam to simulate ,maybe the slover is not very sufficient
Now i know there is a separation of flow on the chord ,maybe that is why my Cl are lower than the experiment data.
but i need some experiment data for airfoil without separation or reattachment ,just laminar flow over airfoil .

does anyone know where i can find such data ? or could anyone tell me under which conditions is fulfilled for the laminar flow over airfoil?

May 20, 2009, 08:26	Questions about Cl,Cd of naca0012	#1
darenyang New Member yang qing Join Date: Apr 2009 Posts: 10 Rep Power: 17	hello all, i am new on OF1.5,i want to simulate the naca 0012 wing , i have found experimental results in internet http://www.cyberiad.net/foildata.htm , also i found the parameter of the model, the chord length is 15.24cm, span length 0.91m . i have set my controlDict with forces and forceCoeffs. but i get wrong results , i dont know why ,could anyone help me check my functions _?? functions ( forces { type forces; // Where to load it from (if not already in solver) functionObjectLibs ("libforces.so"); patches ( wall ); rhoInf 1.0; CofR (0 0 0); } forceCoeffs { type forceCoeffs; // Where to load it from (if not already in solver) functionObjectLibs ("libforces.so"); patches ( wall ); rhoInf 1.0; CofR (0 0 0); liftDir (0 1 0); dragDir (1 0 0); pitchAxis (0 0 0); magUInf 10; lRef 0.1524; Aref 0.1387; }

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May 20, 2009, 10:53		#2
dani New Member Daniele Join Date: May 2009 Location: Rome, Italy Posts: 7 Rep Power: 17	Hi! You can try to set pitchAxis to pitchAxis (0 0 1); Other parts seem to be correct. (To tell you all the truth, I'm not sure of the value of Aref, but I think it's ok.) dani

May 26, 2009, 08:34		#3
cwang5 Member John Wang Join Date: Mar 2009 Location: Singapore Posts: 73 Rep Power: 17	Maybe it's caused by the difference in rho? I use 1.225 for my calculations...

May 26, 2009, 15:48		#4
wikstrom Member Niklas Wikstrom Join Date: Mar 2009 Posts: 86 Rep Power: 17	Mabe it's caused by a bad solution?

June 1, 2009, 05:47		#5
darenyang New Member yang qing Join Date: Apr 2009 Posts: 10 Rep Power: 17	thx for all reply, i used SimpleFoam to simulate ,maybe the slover is not very sufficient Now i know there is a separation of flow on the chord ,maybe that is why my Cl are lower than the experiment data. but i need some experiment data for airfoil without separation or reattachment ,just laminar flow over airfoil . does anyone know where i can find such data ? or could anyone tell me under which conditions is fulfilled for the laminar flow over airfoil?