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.
VAWT Struct Cross-Section
Hi,
I am trying to recreate a VAWT model within QBlade, but I am having trouble recreating the cross-section of the strut.
From the CAD model I have been given I have exported the coordinates of the struct geometry, normalised and translated them as required. I have also successfully imported them within QBlade’s aerofoil design module (see screenshot). My issue is creating the required polars for this cross-section to be used within the VAWT model for simulations. I have some understanding of the trailing edge gap required for the software to complete the analysis of aerofoils. I have tried implementing this gap with no success for the analysis. I am able to create a new polar for the strut cross-section start the analysis, however it produces no output.
Is there something I am overlooking? Or is it simply that the software is unable to generate the polar for the given geometry?
(Currently, these struts have been replicated as cylinders within the VAWT model. I used the circular aerofoil generator for this)
Thanks,
Luke
Uploaded files:- You need to login to have access to uploads.
Hi Luke,
XFoil can struggle with such “thick” cross sections. I managed to simulate a similar, although slightly lower thickness, cross section for a strut in XFoil, see the attached image. However in my case the trailing edge opening was much wider.
You can try playing around with the cross section geometry to see if this also works for you. If not, I would consider just using the circular foils generated in QBlade. During the generation of the circular foil you can set a custom drag coefficient that will be used for the circular airfoil. By simply reducing this coefficient slightly you can mimic the behavior of the slightly more aerodynamic cross section you are trying to simulate.
BR,
David
Uploaded files:- You need to login to have access to uploads.
Hi David,
Thank you for the help. As it turns out I stopped just shy of getting it to work before starting this thread. I’ve managed to play around with the TE gap on the struct cross-section and find one that works, so I’ve been able to generate the necessary polar data to use it within my simulation.
Many thanks,
Luke
Uploaded files:- You need to login to have access to uploads.
Hi Luke,
great to hear that it works! The polar looks reasonable, although the boundary layer appears a bit suspicious. It’s important to approach such results with caution, even when you achieve convergence with XFoil. That said, for the strut, this polar data will likely be less critical compared to the polar used for the blade sections.
Best,
David
