Forum
Important Notice for New User Registrations
To combat an increasing number of spam and bot registrations, we now manually approve all new user registrations. While this may cause a delay until your account is approved, this step is essential to ensure the quality and security of this forum.
To help us verify your registration as legitimate, please use a clear name as user name or an official email address (such as a work, university, or similar address). If you’re concerned that we may not recognize your registration as non-spam, feel free to email us at with a request to approve your username.
Blade position setting
Dear David,
I noticed that in the .bld file, I can adjust the physical rotation center of the VAWT blade by setting P_AXIS_[-]. I also observed that in the blade.str file, I can specify XCM_[-], YCM_[-], XCE_[-], YCE_[-], XCS_[-], and YCS_[-]. Using ANSYS, I obtained the shear center and mass center of the blade cross-section, and I assumed that the elastic center coincides with the shear center. Therefore, I made the following settings.
P_AXIS_[-] = 0.3446
XCM_[-] = 0.4138
XCE_[-] = 0.3446
XCS_[-] = 0.3446
YCM_[-] = 0.0
YCE_[-] = 0.0
YCS_[-] = 0.0
However, I later found that the definition of XCE_[-] causes the blade position to shift further relative to the P_AXIS_[-] setting. This left me puzzled about the exact relationship between P_AXIS_[-] and the six other parameters, and how they are interrelated. I could not find a detailed explanation of their connection in the QBlade documentation, which added to my confusion.
Thanks,
Fawei
Hi Fawei,
the P_AXIS, that you choose also defines the reference coordinate system from which the centers (CM, CE and CS) are defined within the cross section.
For a P_AXIS of 0.0 the reference coordinate system would be located at the leading edge, for a P_AXIS of 1.0 at the trailing edge.
After you have set the centers the beam is then automatically positioned at the elastic center (CE) within each cross section.
Positioning the beam at the elastic center (CE) is crucial because it ensures a proper representation of the coupling between bending and torsion in structural and aeroelastic analyses. The elastic center is the point in the cross section through which the line of action of the resultant elastic forces passes when the beam is subjected to bending or torsion.
See the below figure for reference…
Best regards,
David
