[crixman]

Hi all,
as I am experiencing several difficulties in simulating wind turbines:
1) with SimpleFoam + fvOptions, I get unrealistic torque values;
2) with pimpleDyMFoam, with accurate meshes the running time is incredibly long;

I think it could be interesting to propose different default settings for different types of simulations, tips and tricks, etc...
I think the turbomachinery Sig could be an interesting place where to share this informations or a specific page could be setup.
What do you think?

[thg]

Hi Christian,

did you tried MRF?
Of course also in this case you should be extremely aware of the mesh
(especially y+).

We validated a propeller test case against measurements
and got excellent results with MRF approach in a reasonable time.

The key is the mesh and the simulation setup.

regards
ThG

[Sachin m]

Has anyone tried the propeller tutorial in openFoam??
If yes let me know how to go about it.
My allrun file is not working. So iam trying to run it manually.
Can anyone help me out with the steps???

Thanks in advance.

[fertinaz]

Can you post the error msg you have? It should be working without any problems.

[Sachin m]

the thing is the terminal opens and closes all of a sudden when I use allrun.

I run all my cases manually

so I wud lyk to know how to go about with this case.How shall I begin???

[Tobias Adam]

Hello Thorsten Grahs

I did a MRFSimple simulation about a whole Windturbine too.
But my results weren´t excellent.
For example: the simulated torque is 15% lower than the experimental results.
My explanation for this is the fact, that parts of my numerical schemes are first order schemes, because of a lack of stability with high order schemes.

What is your setup like, as you mention it as the key of your simulation.

Furthermore i have the same problem as crixman with pimpledym. The running time is incredibly long and even worse, the torque increases more and more ( 5 times as high as the experimental results and still increasing) but the residuals keep low and look good.

@ Sachin m

read the allrun file, orthe allrun.pre file first and copy the commands. The results of the commands are explained.
e.g.
# - meshing

runApplication blockMesh ---> so you run blockMesh

runApplication surfaceFeatureExtract ---> ...

runApplication snappyHexMesh -overwrite --->

# force removal of fields generated by snappy
\rm -rf 0
cp -rf 0.org 0

Of course you have to wait for the first job to finish before starting the next one.

I hope this helps a bit. And I hope I did not misunderstand your question.

Best Tobi

[kiddmax]

Originally Posted by maddalena

Hi hm86,
I am interested in that paper, but the link does not work. Could you upload the paper here? --> edited: solved, I have downloaded the paper using your link.
Thanks,

mad

Dear maddalena,

Would you please also send me this paper? I can not download it through this link!
Thank you so much!

my email : dlutyezhang@gmail.com

Best regards,
Ye

[be_inspired]

Originally Posted by crixman

Hi all,
as I am experiencing several difficulties in simulating wind turbines:
1) with SimpleFoam + fvOptions, I get unrealistic torque values;
2) with pimpleDyMFoam, with accurate meshes the running time is incredibly long;

I think it could be interesting to propose different default settings for different types of simulations, tips and tricks, etc...
I think the turbomachinery Sig could be an interesting place where to share this informations or a specific page could be setup.
What do you think?

I agree with you.

I am trying right now transientSimpleDyMFoam because as you say, pimpleDyMFoam requires a low CFL number around 1 I think, but when working with airfoils, boundary layer refinement and so, the simulation time is huge.

Any advance in unsteady simulations?

[crixman]

Hi there,
@Thorsten: yeah I tried MRF but I am not getting proper results. I am trying the simulation similar to a centrifugal industrial fan but neither torque nor pressure drop are realistic. For MRF, how many turbine angles and tip-speed ratio simulations did you perform? Any tips on number of cells, boundary layer and type of mesh?

@be_inspired: unfortunately no advances in unsteady simulations! Did you get any better performance with transientSimpleDyMFoam?

Do you guys know if it's possible to use the turbomachinery solvers in foam-extend-3.1?

[taxalian]

Hi everyone whoever is contributing to this interesting thread, may i ask some questions to assist you guys in solving your problem:

a.) are you guys trying to simulate the HAWT? when yes then did you try to simulate only the single turbine blade or the whole turbine?

b.) what type of boundary conditions you use and are the turbulence variables defined properly i.e. based on the flow conditions

c.) how do you define your moving region and what moving parts are taken into account i.e. if their is non-rotating parts involved in your region or not?

d.) which OF version you are using in conjunction with which turbulence model and the numerical schemes?

I think first of all the MRFsimpleFoam is a steady state solver and once you get good covergence of your residuals, one should also have a look on to the convergence behavior of wind turbine power and other flow quantities, may be they are still not converged yet.

The choice of turbulence model is quite decisive in these cases, i would go for Menter SST k-omega turbulence model at least for moving wind turbine cases.

The mesh quality i.e. (the mesh density and the boundary layer) is really the core of your computed results.

Best Regards,
Taxalian

[be_inspired]

Hi Taxalian,

a) whole turbine
b) BC for wall is fixedValue in U when dealing with MRF and movingWallVelocity when simulating using sliding mesh approach. Up to now, KEpsilon turbulence model has been used.
c)Sure. There are non-rotating parts ( nacelle + tower). The moving region is defined by a cellZone while the rest of domain is fixed.
d) OF2.3.x because in my case there were some bugs in OF2.3.0 when dealing with AMI interfaces (weight=0 when it is not).
Numerical Schemes for me has been the key at least for MRF simulation.

In relation to MRF, I have obtained qualitative good results over blades surface and now I have moved the results to pimpleDyMFoam.

In relation to pimpleDyMFoam, I have increased the nOuterCorrectors as a way to couple U-p while obtained high CFL values.

Threequestion:
1.- PIMPLE control. correctPhi yes or no?
2.- Any idea about maximum CFL that can be achieved using higher nOuterCorrectors with pimpleDyMFoam?

Best Regards

[mohsen.boojari]

sorry but it seems your link doesn't exist or work properly !

[mspranavmn]

Hello, I am trying actuator line method for the first time. Can someone guide me with the criteria /conditions for the design? As in, are the lines with a circular cross-section or same cross-section as the blade profile.

Thank you.

Originally Posted by ibrhmbysl

ı need a 3D analysis but ı have not been able to generate the mesh yet, please help me