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While running a CFD simulation comparison of 2 vs 3 blade propeller versions (48" diameter, 23" pitch, 3570RPM), I've come up with:

  • 2-blade: 347N of static thrust @ 110Nm Torque
  • 3-blade: 220N of static thrust @ 108Nm of Torque

What is the main destructive force seen in the 3-blade propeller particle flow?

Are these "not so tippy" blade tip losses, happening even 60% radius?

The number of particles shown is the same, but in the 3-blade version the same particles are being sucked-back into the flow, which explains the drop in the propeller performance.

2 blade CFD simulation

3 blade CFD simulation

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    $\begingroup$ are the propellers standing still w.r.t. the air mass or is there relative motion? $\endgroup$ – Federico Dec 5 '16 at 11:29
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    $\begingroup$ It looks like your three blade propeller creates a vortex ring state. What is the forward speed of the propeller w.r.t the undisturbed air mass? It seems the propeller is static. $\endgroup$ – DeltaLima Dec 5 '16 at 13:12
  • $\begingroup$ It is a static flow simulation with the dynamic airspeed = 0 m/s. Atmospheric conditions are 101325Pa. I thought Vortex Ring state is only possible with the negative airspeed? $\endgroup$ – FlegmatoidZoid Dec 6 '16 at 10:44
  • $\begingroup$ From the picture it looks like the angle of attack of the 3-blade is much higher than the 2-blade? $\endgroup$ – Koyovis May 6 '17 at 17:32

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