# Wind turbine torque calculation is less than expected

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February 20, 2015, 08:21
Wind turbine torque calculation is less than expected
#1
New Member

Ahmed
Join Date: Dec 2014
Posts: 2
Rep Power: 0
Hi !! help is needed
I am simulating a HAWT but the tesults seems to deviate from the experimental results ( Torque and drag are the main focus of my study)

The case is as follows
Velocity inlet, Pressure outlet
the control volume consists of three zones upper-stream, Moving Zone and Down-stream
V=-10 m/s in the x direction
Moving Zone is MRF around x axis X=1 , Y=0, Z=0 and
w= -133 rad/s which corresponds to the optimum tip speed ratio of 6.
CFD algorithm SIMPLE (default option)
Turbulent model K-epsilon standard near wall function
Interpolating scheme for the first 10 iteration 1st order upwind were used then for 1000 iteration followed 2nd order were used
Pressure (Standard)
Density (Second Order Upwind)
Momentum (Second Order Upwind)
Modified Turbulent Viscosity (Second Order Upwind)
can anyone tells me why the torque value is very low its 13 N.M while in real case its around 85 N.M
Attached Images
 FFF 5.jpg (27.2 KB, 36 views) streamlines.jpg (36.3 KB, 39 views) case.jpg (25.8 KB, 35 views) case2.jpg (24.2 KB, 30 views) casesetup.jpg (59.0 KB, 33 views)

February 20, 2015, 14:56
#2
New Member

Ahmed
Join Date: Dec 2014
Posts: 2
Rep Power: 0
I did something that seems to enhance the torque but it is still lower than expected what i did is as described in the thread (Impact of pressure on the blades with MRF?) @maverick90 which i recommend you to read its very helpful i the case as @ghost82 stated to set the walls of the zones as absolute with 0 rad/s but he also stated to take into account the boundary condition at the inlet which i think is the problem here because when i set the velocity to be normal to boundary condition it gives me components value in all direction in x, y, z
that`s why i choose the velocity in absolute in x-components to be 10 m/sec i don`t whats wrong but when i computed the maximum velocity from the gradient and it reached only 3.6 m/sec.
can anyone tells me what to do to solve this problem.

Attached Images
 trial withno interfaces.jpg (38.0 KB, 21 views) blade.jpg (26.3 KB, 12 views)

 Tags case set-up, drag force, hawt wind turbine, mrf. moving wall, torque