# Negative moment while simulating wind turbine

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 October 19, 2016, 06:59 Negative moment while simulating wind turbine #1 New Member   Angelika Join Date: Jun 2016 Posts: 3 Rep Power: 3 Hi everyone, I'm simulating rotating wind turbine and my aim is to find maximum power. Specification: -rated power 6,150 kW, -rated wind speed (inlet) 14 m/s, -rated rotor speed 12,1 rpm (rigid body motion). I'm getting good thrust value (about 4300 kN), but torque value is negative (about -30 MNm) what is non acceptable, it should be about 5 MNm. I have tried many things (refine mesh, size domain etc). I think the problem may lie in wrong defining moment report. What should be my coordinate system for moment report? Local coordinate system which I have placed in the center of rotating plane? Please help me. domain.jpg Torque.jpg turbina wiatrowa 1 - nowy kat 1_Q Monitor Plot.png Thrust.jpg turbina wiatrowa 1 - nowy kat 1_Residuals.jpg

 October 19, 2016, 09:08 #2 Senior Member   Matt Join Date: Aug 2014 Posts: 608 Rep Power: 8 What does your residual plot look like?

 October 19, 2016, 09:24 #3 New Member   Angelika Join Date: Jun 2016 Posts: 3 Rep Power: 3 The first one with k-epsilon turbulence model, second with k-omega SST. On the second one, there is a change in values of residuals in 5s (one rotation). And the second one simulation has no tower, only rotor. turbina wiatrowa 1 - nowy kat 1_Residuals.jpg turbina wiatrowa 1 - unsteady - nowy kat 3 v=14 I=18_Residuals.jpg

 October 19, 2016, 09:26 #4 Senior Member   Matt Join Date: Aug 2014 Posts: 608 Rep Power: 8 Why are you plotting residuals against physical time? Can you share a screen shot of your physics continua?

 October 19, 2016, 09:33 #5 New Member   Angelika Join Date: Jun 2016 Posts: 3 Rep Power: 3 This is how it looks like. I have 5 mln cells in rotating region and 1,8 mln in stationary region. Time step 0,013(8) s, because 12 rpm, so takes 5 s to complete one full revolution. 5s/360 deg = 0,013(8) s. Don't know where is the problem, I'm beginner with cfd.. resiudua.jpg

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