Can OpenVSP Calculate Propeller with Vx inflow and Vz inflow?

[赵天铭]

Hello everyone,
I'm currently working on unsteady propeller simulations in OpenVSP. While attempting to define angles of attack (alpha) and sideslip angles (beta) for the propeller disk, I noticed that the results only show axial freestream flow.

However, my goal is to compute the three-axis thrust forces (Fx, Fy, Fz) and moments (Mx, My, Mz) with both Vx inflow and Vz inflow about 10m/s.

Does OpenVSP support the situation like this?

Thanks in advance for your help!

[Rob McDonald]

This shouldn't be a problem.  Can you post a file with your attempt that is not giving expected results?

Rob

[zepp Zhao]

Sorry for the late reply. After receiving your response last time, I kept trying to solve the problem, but unfortunately, I failed.

The file I attempted is below. The screenshot shows my simulation results: the trailing wakes are still axial, and the output data only contains axial thrust

Could you please advise on how to resolve this?

[Brandon Litherland]

What version of OpenVSP are you using? I ran this in 3.44 and got similar behavior. Again, what kind of behavior are you expecting?

Your example model is 30 length units in diameter spinning at 2000 RPM for only 5 revolutions, matching essentially the default geometry and settings. This is not a particularly realistic configuration so I have to wonder what led you to run this particular case.  Have you tried running the example prop.vsp3 that is distributed with the software?

Incidentally, the Cartesian forces and moments are in the *.group file written after the run completes.

[zepp Zhao]

Thank you for your reply. I used 3.26.1 OpenVSP. I will try the example prop.vsps to learn more.

I want to run a calculation for a propeller rotating around the Z-axis under incoming flow conditions with Vx=10m/s and Vz=10m/s at same time, and then calculate its three-directional forces and three-directional moments. I expect that the trailing wakes are not only below the propeller, but due to the existence of Vx, to be blown towards the side-lower region of the blade.

[Brandon Litherland]

You should update to the latest OpenVSP for starters but that isn't the main issue.

I understand what you are trying to do but your model in no way reflects those conditions.  If your model is in meters then the rotor is 30 meters in diameter. You have it set to turning at 2000 RPM.

By comparison, the UH-60 has roughly 18 m diameter rotors which turn less than 300 RPM.  Let's take that as an example and set alpha so you have 10 m/s Vx (U) and 10 m/s Vz (W).  I assume this corresponds to 10 m/s forward and up for the aircraft.  Approximating the UH-60 rotor, the simulation behaves exactly as one would expect. The viewer shows the rotor wakes traveling primarily down and somewhat aft.

Take some time to refine your model, size the rotor/propeller appropriately, and determine what conditions might be feasible for your aircraft.