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