how to Analyze and simulate 4-rotor UAV (simulation results)

- October 6, 2018 at 1:29 pm
  
  fa-ri
  Subscriber
  
  Hello all,
  
  I'm working with ANSYS 18.2 version,
  
  I'm doing a 3d simulation of flow field for a 4-rotor UAV.
  
  I have a transient state case.
  
  The steps I did:
  
  1.used (realizable.k-e.scalable wall fn)
  
  2.turn on mesh motion for each blade
  
  3.used 2 pressure outlet
  
  4.time step size :0.01
  
  The lift values obtained for each rotor are small and negative and The flow lines are not symmetric
  
  please help me:
  
  1. How do I know that my simulation is correct?
  
  2. How to calculate the total lift and thrust values
  
  Thank you
  
  With regards
  
  fa-ri
- October 8, 2018 at 5:36 am
  
  seeta gunti
  Ansys Employee
  
  Hello Fari,
  
  Regarding calculation of lift and drag, we have a tutorial in the youtube. Please watch the video as given below.
  
  https://www.youtube.com/watch?v=gB33UcgKG3c
  
  Make sure that you gave the correct input values for rotor axis direction, axis center and rotational speed ( RPM/ RPS).
  
  Regards,
  
  Seeta
- October 8, 2018 at 7:46 am
  
  fa-ri
  Subscriber
  
  Hello Seeta
  
  Thank you for your response.
  
  here is my data
  
  Forces - Direction Vector (0 1 0)
  
  Forces (n) Coefficients
  
  Zone Pressure Viscous Total Pressure Viscous Total
  
  prop_1 0.017310849 -9.460496e-05 0.017216244 0.028262611 -0.00015445708 0.028108154
  
  Net 0.017310849 -9.460496e-05 0.017216244 0.028262611 -0.00015445708 0.028108154
  
  But the result is not correct by comparing values with experimental values.
  
  and about the steamlinesThere is a lot of Wake streams.
  
  how can i khow that my simulation is correct?
- October 8, 2018 at 10:45 am
  
  seeta gunti
  Ansys Employee
  
  Hello Fari,
  
  Please make sure that you give the right boundary conditions and right axis rotation and center of axis of the rotor. Sometimes, the speed will be given wrong. Please check you use the right units.
  
  Refer some tutorials on mesh motion with some rotational speed in Youtube to check your settings.
- October 8, 2018 at 10:53 am
  
  Karthik Remella
  Administrator
  
  Hello,
  
  Just to add to Seeta's comments, if you are seeing discrepancies only in the coefficients (and your forces seem correct), you might want to take a look at your reference values).
  
  Thank you.
  
  Best Regards,
  
  Karthik
- October 8, 2018 at 12:10 pm
  
  fa-ri
  Subscriber
  
  Hello Karthik,
  
  Thank you for your response.
  
  I've checked the values (both) and the amount is too much lower than reality
  
  With regards
  
  fa-ri