# Wind turbine simulation

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 August 30, 2009, 07:23 #21 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144 Have you read through this? http://www.cfd-online.com/Wiki/Ansys...gence_criteria

April 23, 2010, 03:36
#22
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yashwant
Join Date: Apr 2010
Posts: 20
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Quote:
 Originally Posted by sivarama1 Hi all, i am simulating wind turbine ,but here converging problem,any body verify my boundary conditions,is it i was given correct or not. Setting up CFX Solver run ... +--------------------------------------------------------------------+ | | | CFX Command Language for Run | | | +--------------------------------------------------------------------+ LIBRARY: CEL: EXPRESSIONS: dt = 0.04 [s] END END MATERIAL: Air Ideal Gas Material Description = Air Ideal Gas (constant Cp) Material Group = Air Data, Calorically Perfect Ideal Gases Option = Pure Substance Thermodynamic State = Gas PROPERTIES: Option = General Material ABSORPTION COEFFICIENT: Absorption Coefficient = 0.01 [m^-1] Option = Value END DYNAMIC VISCOSITY: Dynamic Viscosity = 1.831E-05 [kg m^-1 s^-1] Option = Value END EQUATION OF STATE: Molar Mass = 28.96 [kg kmol^-1] Option = Ideal Gas END REFERENCE STATE: Option = Specified Point Reference Pressure = 1 [atm] Reference Specific Enthalpy = 0. [J/kg] Reference Specific Entropy = 0. [J/kg/K] Reference Temperature = 25 [C] END REFRACTIVE INDEX: Option = Value Refractive Index = 1.0 [m m^-1] END SCATTERING COEFFICIENT: Option = Value Scattering Coefficient = 0.0 [m^-1] END SPECIFIC HEAT CAPACITY: Option = Value Specific Heat Capacity = 1.0044E+03 [J kg^-1 K^-1] Specific Heat Type = Constant Pressure END THERMAL CONDUCTIVITY: Option = Value Thermal Conductivity = 2.61E-2 [W m^-1 K^-1] END END END END FLOW: SOLUTION UNITS: Angle Units = [rad] Length Units = [m] Mass Units = [kg] Solid Angle Units = [sr] Temperature Units = [K] Time Units = [s] END SIMULATION TYPE: Option = Transient EXTERNAL SOLVER COUPLING: Option = None END INITIAL TIME: Option = Automatic with Value Time = 0 [s] END TIME DURATION: Option = Total Time Total Time = 300.0*dt END TIME STEPS: Option = Timesteps Timesteps = dt END END DOMAIN: rotordisc Coord Frame = Coord 0 Domain Type = Fluid Fluids List = Air Ideal Gas Location = turbine Assembly,turbine Assembly 2 BOUNDARY: discback Side 1 Boundary Type = INTERFACE Location = DISKOUTLET,DISKOUTLET 2 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: frontdisc Side 2 Boundary Type = INTERFACE Location = DISKINLET,DISKINLET 2 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: outerdisc Side 1 Boundary Type = INTERFACE Location = SHROUD 2,SHROUD BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: per1 Side 1 Boundary Type = INTERFACE Location = PER1 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: per1 Side 2 Boundary Type = INTERFACE Location = PER2 2 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: per2 Side 1 Boundary Type = INTERFACE Location = PER1 2 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: per2 Side 2 Boundary Type = INTERFACE Location = PER2 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: rotordisc Default Boundary Type = WALL Frame Type = Rotating Location = BLADE,BLADE 2,HUB,HUB 2 BOUNDARY CONDITIONS: WALL INFLUENCE ON FLOW: Option = No Slip END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Alternate Rotation Model = On Angular Velocity = 71.9 [rev min^-1] Option = Rotating AXIS DEFINITION: Option = Coordinate Axis Rotation Axis = Coord 0.3 END END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Fluid Temperature = 283.15 [K] Option = Isothermal END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = SST END TURBULENT WALL FUNCTIONS: Option = Automatic END END INITIALISATION: Coord Frame = Coord 0 Frame Type = Rotating Option = Automatic INITIAL CONDITIONS: Velocity Type = Cylindrical CYLINDRICAL VELOCITY COMPONENTS: Option = Automatic with Value Velocity Axial Component = 10 [m s^-1] Velocity Theta Component = 0 [m s^-1] Velocity r Component = 0 [m s^-1] END K: Fractional Intensity = 0.05 Option = Automatic with Value END OMEGA: Option = Automatic END STATIC PRESSURE: Option = Automatic with Value Relative Pressure = 101325 [Pa] END END END END DOMAIN: tunnel Coord Frame = Coord 0 Domain Type = Fluid Fluids List = Air Ideal Gas Location = tunnel Assembly BOUNDARY: discback Side 2 Boundary Type = INTERFACE Location = F521.452,F519.452 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: frontdisc Side 1 Boundary Type = INTERFACE Location = F516.452,F518.452 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: inlet Boundary Type = INLET Location = inlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Normal Speed = 10 [m s^-1] Option = Normal Speed END TURBULENCE: Option = High Intensity and Eddy Viscosity Ratio END END END BOUNDARY: outerdisc Side 2 Boundary Type = INTERFACE Location = F515.452,F517.452 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: outlet Boundary Type = OUTLET Location = outlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Option = Average Static Pressure Relative Pressure = 0 [Pa] END PRESSURE AVERAGING: Option = Average Over Whole Outlet END END END BOUNDARY: tunnel Default Boundary Type = WALL Location = \ F522.452,F524.452,F525.452,F526.452,F527.452,F528. 452,F529.452,F530.4\ 52,F531.452,F532.452,F541.452,F551.452 BOUNDARY CONDITIONS: WALL INFLUENCE ON FLOW: Option = No Slip END END END BOUNDARY: wall Boundary Type = WALL Location = wall BOUNDARY CONDITIONS: WALL INFLUENCE ON FLOW: Option = No Slip END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Fluid Temperature = 283.15 [K] Option = Isothermal END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = SST END TURBULENT WALL FUNCTIONS: Option = Automatic END END INITIALISATION: Coord Frame = Coord 0 Option = Automatic INITIAL CONDITIONS: Velocity Type = Cartesian CARTESIAN VELOCITY COMPONENTS: Option = Automatic with Value U = 10 [m s^-1] V = 0 [m s^-1] W = 0 [m s^-1] END K: Fractional Intensity = 0.05 Option = Automatic with Value END OMEGA: Option = Automatic END STATIC PRESSURE: Option = Automatic with Value Relative Pressure = 101325 [Pa] END END END END DOMAIN INTERFACE: discback Boundary List1 = discback Side 1 Boundary List2 = discback Side 2 Interface Type = Fluid Fluid INTERFACE MODELS: Option = General Connection FRAME CHANGE: Option = Transient Rotor Stator END PITCH CHANGE: Option = None END END MESH CONNECTION: Option = GGI END END DOMAIN INTERFACE: frontdisc Boundary List1 = frontdisc Side 1 Boundary List2 = frontdisc Side 2 Interface Type = Fluid Fluid INTERFACE MODELS: Option = General Connection FRAME CHANGE: Option = Transient Rotor Stator END PITCH CHANGE: Option = None END END MESH CONNECTION: Option = GGI END END DOMAIN INTERFACE: outerdisc Boundary List1 = outerdisc Side 1 Boundary List2 = outerdisc Side 2 Interface Type = Fluid Fluid INTERFACE MODELS: Option = General Connection FRAME CHANGE: Option = Transient Rotor Stator END PITCH CHANGE: Option = None END END MESH CONNECTION: Option = GGI END END DOMAIN INTERFACE: per1 Boundary List1 = per1 Side 1 Boundary List2 = per1 Side 2 Interface Type = Fluid Fluid INTERFACE MODELS: Option = General Connection FRAME CHANGE: Option = None END PITCH CHANGE: Option = None END END MESH CONNECTION: Option = Automatic END END DOMAIN INTERFACE: per2 Boundary List1 = per2 Side 1 Boundary List2 = per2 Side 2 Interface Type = Fluid Fluid INTERFACE MODELS: Option = General Connection FRAME CHANGE: Option = None END PITCH CHANGE: Option = None END END MESH CONNECTION: Option = GGI END END OUTPUT CONTROL: RESULTS: File Compression Level = Default Option = Standard END TRANSIENT RESULTS: Transient Results 1 File Compression Level = Default Option = Standard Output Boundary Flows = All OUTPUT FREQUENCY: Option = Timestep Interval Timestep Interval = 101 END END END SOLVER CONTROL: ADVECTION SCHEME: Option = High Resolution END CONVERGENCE CONTROL: Maximum Number of Coefficient Loops = 10 Minimum Number of Coefficient Loops = 3 Timescale Control = Coefficient Loops END CONVERGENCE CRITERIA: Conservation Target = 0.01 Residual Target = 1.E-4 Residual Type = RMS END TRANSIENT SCHEME: Option = Second Order Backward Euler TIMESTEP INITIALISATION: Option = Automatic END END END END COMMAND FILE: Results Version = 11.0 Version = 11.0 END EXECUTION CONTROL: INTERPOLATOR STEP CONTROL: Runtime Priority = Standard EXECUTABLE SELECTION: Double Precision = Off END MEMORY CONTROL: Memory Allocation Factor = 1.0 END END PARALLEL HOST LIBRARY: HOST DEFINITION: sivaram Installation Root = C:\Program Files\Ansys Inc\v%v\CFX Host Architecture String = amd_opteron.sse2_winnt5.1 END END PARTITIONER STEP CONTROL: Multidomain Option = Independent Partitioning Runtime Priority = Standard EXECUTABLE SELECTION: Use Large Problem Partitioner = Off END MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARTITIONING TYPE: MeTiS Type = k-way Option = MeTiS Partition Size Rule = Automatic END END RUN DEFINITION: Definition File = D:/tutorial/CFX/wind_3blade3_002_001.def Initial Values File = D:/tutorial/CFX/wind_3blade2_002_001.res Interpolate Initial Values = Off Run Mode = Full END SOLVER STEP CONTROL: Runtime Priority = Standard EXECUTABLE SELECTION: Double Precision = Off END MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARALLEL ENVIRONMENT: Number of Processes = 1 Start Method = Serial END END END

hi sir,
can u send me the boundary conditions which u applied in cfx so i can try the solution in cfx too.

April 16, 2011, 00:31
#23
Senior Member

Join Date: Dec 2010
Location: UK
Posts: 245
Rep Power: 16
Quote:
 Originally Posted by ghorrocks Hi, But assuming each blade is equally loaded then the total power is simply n times the power of one blade, regardless of how much power additional blades actually add. Also you may find the turbo machinery macro in CFD-Post useful in post-processing this. Glenn Horrocks
Dear Glenn,
Although the original thread looks outdated, but when I read your answer and Suraj's reasons, I became confused that Suraj is right somewhat, and you 100%. Because the blades will be equally loaded in axial steady case ,but the points that Suraj says also make sense.

Do you have any solution for this contradiction or you just say"REGARDLESS" what the real/theoretical results are... it will be "n" times the results of single blade. Then, if you confirm the previous answer what is the cause of this HUGE difference between this two...? and PLZ remember than Suraj's points are in contradiction with energy conservation law...

TNX

 April 16, 2011, 07:34 #24 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144 My point was simply that for even blade loading, each blade supplies 1/n of the torque. I said nothing about how much extra torque you get by adding more blades. That is a different question so don't get confused.

October 7, 2013, 13:54
5 MW offshore wind turbine
#25
New Member

sattar
Join Date: Dec 2011
Posts: 18
Rep Power: 14
Hi for all
I am trying to simulate 5 MW offshore wind turbine (aerodynamics study only) using CFX to validate my results which were coming from another solver, under these conditions
· Full scale of 5 MW offshore wind turbine dimensions
· transient analysis
· Inlet velocity = 9 m/sec
· 3 blade rotor + hub (rotating domain) with angular velocity =1.08 rad/sec
· Nacelle + tower (stationary domain)
· Then, three interfaces have been defined between the stationary domain and the rotating domain due to changes in reference frames. In order to rotate the rotor in ANSYS.
· I create appropriate and suitable meshes for all the parts in ICEM and CFX is specifying domains, boundary conditions, type of analysis, interfaces, etc.

But I always I find this error

First side of interface |
| Domain Interface 1 |
| seems to contain a vertex at R=0 (Rmin/Rrange < GGI ETA TOLERANCE).|
| This is not supported with |
| PITCH CHANGE/Option = Automatic |
| Please use |
| PITCH CHANGE/Option = None |
+--------------------------------------------------------------------+
+--------------------------------------------------------------------+
| ********* WARNING ********* |
| Coordinate transformation of interface |
| Domain Interface 2 |
| into a radial interface resulted in some faces with a very small |
| axial extent. There are two possible reasons for this: |
| 1. The interface contains axial faces (normal to the axis). |
| If this is the case, please split the interface into two parts, |
| so that the purely axial sections could be transformed |
| properly. The transformation type (axial or radial) is chosen |
| automatically based on the largest interface extent. |
| 2. This message may be generated because of a tolerancing issue |
| when the mesh resolution in the axial direction is very |
| small (e.g. at the hub or shroud). If this is the case, you |
| may ignore this message. |
+--------------------------------------------------------------------+
+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| ****** FATAL ERROR ****** The orthographic view transformation fa- |
| iled on domain interface "Domain Interface 2". Failure may be du- |
| e to r=0 included in transformed cylindrical coordinates of an in- |
| terface with rotational relative motion. Another reason could be |
| that the interface contains faces that are parallel and others t- |
| hat are perpendicular to the rotation axis. |
+--------------------------------------------------------------------+

</SPAN>

When I selected (PITCH CHANGE/Option = Automatic ) which I thought is correct chose but the above error will appear
And when I selected (PITCH CHANGE/Option = None) the run continue and complete, everything is ok, but the values of torque is negative ????
thanks
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 October 7, 2013, 17:42 #26 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144 It looks like you are modelling the whole thing so you are correct to use pitch change=none. As for the negative torque, have you checked the vector direction of the torque?

 October 7, 2013, 17:55 #27 New Member   sattar Join Date: Dec 2011 Posts: 18 Rep Power: 14 hi do you means that, by using the right hand rule can i find the torque direction thanks

 October 7, 2013, 18:08 #28 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144 Just had a look at the torque function in the CFX reference manual. If you use the torque_x, torque_y, torque_z functions it returns the torque about the X, Y and Z coordinate axis respectively (and yes you can use the RH rule to get the direction). But the axis specification is optional and it is not clear what axis it uses if you just use the torque function with no axis defined. Does anybody know what axis the torque function uses if no axis is defined? To get around this I would just use the torque_x/y/z functions so you know exactly what axis it is using.

 October 8, 2013, 05:45 #29 New Member   sattar Join Date: Dec 2011 Posts: 18 Rep Power: 14 thanks for your answer but I calculate the torque of the rotor on the rotation axis torque_x()@BLADE +torque_x()@BLADE1 +torque_x()@BLADE2 which appear for me negative despite of the rotation of the blades counter-clockwise

 October 8, 2013, 05:48 #30 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144 To get the correct result in a rotating machine simulation, you need to not only get the numerics correct, but you also need to get the operating point correct. This means that the rotation speed might be a little faster or slower. So negative torque means the rotation speed is slower - assuming your simulation is accurate. sagarmore likes this.

 October 8, 2013, 06:55 #31 New Member   sattar Join Date: Dec 2011 Posts: 18 Rep Power: 14 can I give a negative value for the rotation speed for the rotational domain and I checked some of paper that use the same rotational speed with the same dimension of my wind turbine and got a positive value of torque

October 8, 2013, 07:45
#32
Senior Member

Join Date: Dec 2010
Location: UK
Posts: 245
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Quote:
 Originally Posted by drsattar can I give a negative value for the rotation speed for the rotational domain and I checked some of paper that use the same rotational speed with the same dimension of my wind turbine and got a positive value of torque
Yeah, you can do it In CFX

 October 8, 2013, 07:53 #33 New Member   sattar Join Date: Dec 2011 Posts: 18 Rep Power: 14 thanks again you are so helpful and I will try to do simulation with -1.08 rad/s

 October 16, 2014, 03:08 3 d simulation of helicel turbine in cfx #34 New Member   rajendra singh Join Date: Jul 2013 Posts: 11 Rep Power: 13 hi, i m trying to simulate a helical turbine but i only know the inlet velocity.so how to perform transient analysis? of it.Do i need to take two domain one stationary and one rotating?plz suggest something

 October 16, 2014, 05:27 #35 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144 You will need to know a pressure somewhere to set the pressure level. Look at the CFX tutorials for how to run simulations. And in future, if you have a new question start a new thread rather than hijacking an old thread.

 February 1, 2016, 07:51 inquiry about wind power using ansys fluent 15 #36 New Member   hossam elbakry Join Date: Apr 2015 Posts: 7 Rep Power: 11 hello, i am using fluent 15, after i draw the horizontal turbine using solidworks, i made a run of fluent with omega and input wind speed, using k-omega sst model, the resultant torque multiplied with the omega to get the power. the question is: the calculated power using ansys can be compared with the net power of commercial turbine directly, " or should be multiplied to rotor efficiency first before comparing with net power of commercial turbine?

 February 1, 2016, 15:54 #37 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144 The power at the rotor shaft (torque x omega) should match the torque at the rotor shaft of the turbine.

 February 1, 2016, 16:59 #38 New Member   hossam elbakry Join Date: Apr 2015 Posts: 7 Rep Power: 11 but i am not comparing with torque at the rotor shaft of the turbine,,, i am comparing power from ansys ( omega x torque) with the net producing power from the generator where the commercial turbine connected to. so i think that a parameter of efficiency of rotor and generator and inverter should be included.

 February 1, 2016, 17:35 #39 New Member   Kyriakos Vafiadis Join Date: Feb 2011 Location: Kozani, Greece Posts: 29 Rep Power: 15 You can only compare the CFD computed rotor power to the rotor power of the real machine. If it's not possible to find the real rotor's power, you may need to find it by either experiment (if it's possible) or by asking the manufacturer. If you know the efficiency of the generator, etc, you should try to use it to make an approximation of the net aerodynamic rotor power. __________________ -- Kyriakos Vafiadis Mechanical Engineer, PhD candidate

 February 1, 2016, 18:56 #40 New Member   hossam elbakry Join Date: Apr 2015 Posts: 7 Rep Power: 11 you are correct,,,i am trying to compare the ansys power (torque x omega) with the generator power ,,,,but i think the rotor efficicency and inverter efficiency and generator efficiency should be included,, am i right?

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