Integral Force calculation in CFX 12 - wind blade case
I'm solving wind blade case as part of my HAWT analysis. I have geometry of a blade+nacelle-like body+ cylindrical far field (120 degree part).
BCs - top and bottom of the cylindrical FF as Inlet and Outlet
external surface as Wall
+ interface BCs for Fluid/Solid interfaces
Details - 10 m/s flow for Inlet
1 atm static pressure for Outlet
Rotated reference frame is specified for inlet velocity to simulate rotation of the wind turbine rotor.
Task - to evaluate torque of the rotor in steady state (with constant rotational velocity) - shaft torque
I've performed this analysis for different angles of attack of the blade but the result Torque_X (rotor is X oriented) was very small - 0.02 Nm or smth around.
Then I've tried to calculate overall force on the blade. I've used areaInt(Force)@ on the surface of the blade (2D region). But the results are still not logical - couple of Ns or even negative values.
What I'm doing wrong? And how to calculate torques and integral values correctly?
Here some pics (whole rotor is made by using mirroring function of CFD Post)
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