Hello guys, I am in real need, I am working on my diploma thesis and the deadline is really close. I am having a bit of trouble with getting correct results of CL and CD from simulation over a rotating airfoil.
This is what I did so far:
I followed this video on youtube: https://www.youtube.com/watch?v=G0zAHv0rEa8 to make the rotating aifoil by creating to interface zones one is fluid, and the other one is inside of it - rotating - and inside this one is my airfoil as a rotating wall... My airfoil´s chord line has 1 meter. I situated the airfoil in the middle of the rotating circle... I set the rotation of the rotating part -0,5 radians... time step is 0,005 and the number of timesteps is 200.. Simulation is fine just my values of CL and CD are crazy high, I dont know where I could make a mistake. Here is the picture of the lift curve generated by fluent in "report definitions"..
If there will be need to upload any other screenshots just let me know. If anyone would be able to get me out of this desperate situation I would be very grateful. Thank you :)
If all boundary conditions are set correctly, I would investigate if a finer mesh would generate better results. Second, try to increase the total time of the simulation and decrease the convergence error. Third, try to use different turbulence model, as SST for example.
Hello Willian, Thank you for you answer.
I set boundry condition for airfoil, inlet and outlet, just like it is in the video.... To be true I am not specialist, but the mesh looks fine enough to me... Do you have any idea how to improve it? I did 2nd and the 3rd point as you suggested but it didnt help.. I let it run fo 600 time steps and the time step size as 0,005, so the whole process was running 3 seconds instead of 1.. OR you think I should do more? Thank you again,
Best regards,
Kristian
Hello Muddasar, thank you for your response, Yes I am sure that I set the lift coeffcient in report definitions. here I cana ttach the picture... Okay I will try to run it without rottating mesh and I will see... Can I ask you what do you mean by "preview mesh motion only"? Thanks a lot for you advices I will try to run it without the motion and I will update here the results.
Hello Muddasar,
I tried to run it without rotating and the airfoil, and the rotating airfoil and the lift curve now looks like this...
When I go results ->reports ->forces and I put y=1 and x=0, which I found out on internet that should be a value for lift coeffcient is 2,7, which is still to high at 0 angle of attack
Could you maybe be please check the setting that are in video I posted at first, bcs I did everything in the same way I just used my airfoil.. the problem with the video is that he doesnt really show how to calculate lift and drag coeff...
Thank you
Hello Muddasar,
Thank your for coming back to me... I checked the link, and even if my version of ansys is a bit different I think I have set everything right, (I managed to find a proceedure how to set the force coefficent few days before) I checked everything twice and the value is still same...
I tried to copy your comand and paste to the console, but it was declared as an invalid comand.
Here is the whole file for the my airfoil, if you would be able to look at it I would be grateful, thank you so much, I already tried the CFD-forum online, but I didnt get so much responds there...
Hello Muddasar!
Thank you for your effort! You just made my day and enabled me to move finally forward! I did it as you and it worked! I cannot believe that one click took 2 days of my life :D I cannot express my grattitude by words...
Like I mentioned before I new to CFD simulation so I am not sure how I could improve the quality of mesh.. but the reults are good enough for me I think :) Thanks again for your guide throught this problem...
Have good one :)
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