Hello,
I'm trying to calculate the force that is acting on the shaft of a VAWT (to get the bending moment). I'm pretty sure that QBlade is giving me all the information I need for the calculation, but I'm stuck anyway. I need the information to dimension the shaft of a small 3D-printed VAWT. Since a thrust is a force, there must be a certain point on which it's act. Is it the center of the rotor? Thanks a lot!
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the thrust is the force acting on the rotor which does not cause the rotor to rotate. All blade stations contribute to the thrust with the force vector thats pointing outside the rotational path. Depending on the azimuthal position of the rotor the sum of all these vectors points in different directions. If you assume a rigid rotor the force will act on the connecting point between rotor and tower and it will also cause a moment acting at the connecting point.
Cheers,
David
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Anonymous
Anonymous
-
2019-10-15
Hello David and thanks for the discussion and the invaluable work at QBlade; so to summarize:
Which can we say is the point of application of the X,Y,Z Thurst given in output by QBlade?
Since for different points of application we should find different transport moments to a considered connection point, and therefore different bending effects on substructures.
So can we say the point of application is the centroid of the rotor?
In that case anyone could calculate bending effects to its substructures
Thank you again Tommaso
PS we will write soon to you from windcity.it
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the application point is currently not saved as an output in QBlade.
With the release of the next version the aerodynamic loads will be explicitly applied at their origin onto the structural model - so this will be talen care of automatically.
If you want to calculate the application point with the current version of QBlade you can do so by outputting the normal and tangential force distributions from blade graphs and the calculating the application point, and the total force vector, from the azimuthal positions of the blades.
Best,
David
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Hello,
I'm trying to calculate the force that is acting on the shaft of a VAWT (to get the bending moment). I'm pretty sure that QBlade is giving me all the information I need for the calculation, but I'm stuck anyway. I need the information to dimension the shaft of a small 3D-printed VAWT. Since a thrust is a force, there must be a certain point on which it's act. Is it the center of the rotor? Thanks a lot!
Hello,
the thrust is the force acting on the rotor which does not cause the rotor to rotate. All blade stations contribute to the thrust with the force vector thats pointing outside the rotational path. Depending on the azimuthal position of the rotor the sum of all these vectors points in different directions. If you assume a rigid rotor the force will act on the connecting point between rotor and tower and it will also cause a moment acting at the connecting point.
Cheers,
David
Hello David and thanks for the discussion and the invaluable work at QBlade; so to summarize:
Which can we say is the point of application of the X,Y,Z Thurst given in output by QBlade?
Since for different points of application we should find different transport moments to a considered connection point, and therefore different bending effects on substructures.
So can we say the point of application is the centroid of the rotor?
In that case anyone could calculate bending effects to its substructures
Thank you again Tommaso
PS we will write soon to you from windcity.it
Hi Tommasso,
the application point is currently not saved as an output in QBlade.
With the release of the next version the aerodynamic loads will be explicitly applied at their origin onto the structural model - so this will be talen care of automatically.
If you want to calculate the application point with the current version of QBlade you can do so by outputting the normal and tangential force distributions from blade graphs and the calculating the application point, and the total force vector, from the azimuthal positions of the blades.
Best,
David