Learning Forum

[fa-ri]

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

                               

[seeta gunti]

Hello Fari,

Regarding calculation of lift and drag, we have a tutorial in the youtube. Please watch the video as given below.

Make sure that you gave the correct input values for rotor axis direction, axis center and rotational speed ( RPM/ RPS).

Regards,

Seeta

 

 

 

[fa-ri]

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    

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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?

[seeta gunti]

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.

[Karthik R]

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

[fa-ri]

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