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nomad May 9, 2011 12:18

Propeller Validation Case
Has anybody looked at a propeller validation case in STAR CCM+?
In particular, I'm interested in Re<1e6 cases. In this regime, XROTOR gives way better results than CFD.

I've heard that torque and thrust results are typically 20%-50% off experimental results due to high dissipation in the code.

I'm running cases with both the unsteady Rigid Body Motion and steady state Moving Reference Frame solvers and different turbulence models, and none of them seem to work well. They do better at Re>1e6. I am also following the the best practice meshing guidlines (wall y+<1, stetching factor<1.25, LE/TE refinement, in-place interface >99% intersecting faces, and so on), and a small enough time step.

Thank you.

jenny425 February 14, 2012 21:00

Have you found a propeller to validate your simulation? What did you find out with your code? I'm in the same situation. Thanks!

nomad February 14, 2012 22:05

I haven't found a commercial code that correctly predicts propeller thrust and torque. I have worked with the technical support guys at FLUENT, CFX and STAR CCM+ and although the thrust prediction comes to within 5%, the torque prediction is way off.

I have found however that OVERFLOW (NASA structured code) gives the right results for both thrust and torque to within 1-2% of experimental data. The learning curve is steep but manageable, although you have to be a US citizen in order to use the code.

Unfortunately, at this point in time, the excessive artificial dissipation in commercial codes prevents their use in rotorcraft performance prediction.

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