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-   -   Pitching moment at the quarter chord in CFX (http://www.cfd-online.com/Forums/cfx/87544-pitching-moment-quarter-chord-cfx.html)

 k.vimalakanthan April 22, 2011 13:44

Pitching moment at the quarter chord in CFX

Could someone please tell me how to calculate pitching moment at the quarter-cord location of an airfoil in CFX, as in the CCL expression?

I have been using this equation,
Cm = torque_y()@Airfoil/(Q*c)

Q and c are the dynamic head and chord respectively. This equation seems to give a very different value to my comparison, this is may be due to the fact in CFX the force and the moments are defined at the global coordinate origin, in my case this is the leading edge of the airfoil.
Any help is greatly appreciated,
Thank you.

 siw April 24, 2011 13:59

I think you are missing a reference area in your expression e.g. wing planform area (see http://en.wikipedia.org/wiki/Pitching_moment).

 dae4god July 15, 2011 23:25

Hi k.vimalakanthan,

I was having the same problem as you and the CEL I used to find the moment was:

moment = torque_y_Axis Name()@Airfoil

Axis Name is the axis that you want the pitching moment to be calculated, in your case, an axis at the quarter chord location.

To find the pitching moment coefficient, as siw said, you need to include the reference area so:

CM = moment/(Q*S*c)

Hope that helps :)

 crusen mind April 8, 2016 09:28

constant pitching moment

hello all
so pitching moment is calculated about y axis what is the location of y axis with respect to x and z

 mortazavi April 9, 2016 19:02

Hi all,
this is my question too. Any suggestion for CL and CD and also the location of centre of pressure?
many many thanks

 crusen mind April 10, 2016 06:38

centre of pressure

hello mortazavi,

u can create a local coordinate in cfx post and using function u can estimate moment about local coordinate. where ever u want.

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