# 'New_geometry_VAWA' simulation project by Iria

#1

I created a new simulation project called 'New_geometry_VAWA':

Airflow around a VAWA

More of my public projects can be found here.

#2

@Iria, nice to see you doing some more vertical wind turbine analyses. Looking forward to seeing the results!

#3

Great sim project!

#4

Hi @dheiny!
I need some help with the project â€śVAWA_inlet_1â€ť. For studying the airflow around the turbine IÂ´m using the approach of doing different MRF Simulations all around the vertical turbine changing the flow direction every 30Â°. In this case IÂ´m using a airflow direction of +y and I want to study the possibilities of the** â€śResult controlâ€ť** in depth. And I did not found so much information about it in the documentation.

I think that the parameters of** â€śForces and momentsâ€ť** are ok:

But with the parameters for** â€śForces and moments coefficientsâ€ť** IÂ´m not sure:

Thank you very much for your help!
have a nice day!

#5

sorry, the second screenshot it is not right!

#6

Hi @dheiny! I forgot to ask you something else.
In the project â€śVAWA_inlet_1â€ť under MESH_Topological Entity Sets I select the 47 faces of the rotor and when I create the entity set from the selection in the left side where all the entities are listed, I only see 44 faces for the rotor:

Thank you again!
IÂ´m not asking anymore today

#7

@Iria, so for the last question: The meshed rotor indeed only has 44 faces, but the integer ID that is counted up is not continuous (e.g. 32 and 38 are missing). The CAD model initially had 47 but 3 of the faces are so small, that the coarse mesh does not resolve them, such that they are dropped. In general, this does not mean that the mesh is invalid so you might be able to simply go on. However from the CAD modeling perspective itâ€™s questionable if you want these super small and thin faces in the end of each wing (check out the screenshot below).

For the result control items @gholami and @psosnowski are the guys that might be able to answer this more in detail. @gholami, could you hint @Iria either to the proper part of the documentation or elaborate on them? Thanks!

#8

@Iria, on a related note - @asmauos is right now working on a water turbine concept in this project: https://www.simscale.com/projects/asmauos/turbine_uos where he shared thoughts on different turbine concepts for a water turbine inside a pipe flow. Seems like youâ€™re doing some intense work yourself on these models - maybe you have a hint? I ran a sim of it (fixed rotor) over here: https://www.simscale.com/projects/dheiny/turbine_uos

#9

Thank you @dheiny!
IÂ´m waiting impatient for the answers of your colleges @gholami and @psosnowski

#12

sorry @asmauos, are you talking with me?

#13

Sorry by mistake

#14

Hello lria,
How are you ?
Did you check my project?
As the engineer said, there is some problem in rotational of the turbine.
How can i fix it?
And i uplode a new project also maybe it can work.
Actually, this is my senior project and i have only two days for the final submission, and iâ€™m trying to finish it as soon as possible.
Could you help me please?
I will be thankfull for you.

#15

Hi @Iria, nice work with your setup!

Regarding Forces and moments coefficients, lift and drag are defined based on net flow direction, i.e. lift forces act across and drag forces act along the net flow direction. In your case, with an inlet flow in XY plane, the direction of inlet flow would be drag, lift would be normal to drag in XY plane. Pitch axis is the axis of net moment due to lift and drag forces on turbine and simply equals (0,0,1).

The reference length and area are used in moment calculations. For example, lift coefficient is calculated dividing the total force by the reference area and a calculated reference dynamic pressure. In your case, you could use

• sweeping area of the turbine for reference area, and
• rotor length as reference length (only used for the pitching moment calculation).

Iâ€™m not sure if I understand what you mean. This parameter defines how often you want the result of force and moment calculations to be written to log (and plotted). It is independent of what you specify in simulation control.

I hope this helps.

#16

@gholami - we could look into adding more such information to the documentation, what do you think?

#17

Hi @gholami,

thank you very much for your help! It is very useful.

Then in my case if the lift direction is normal to drag in the plane XY:

• in the case of flow direction (0,1,0), the lift direction would be (1,0,0)
The sweeping area is the area of the turbine blades and for rotor length do you mean the rotor diameter or the rotor height?

Another question: in the plot of the force coefficient, what are these values: Cl(f) and ClÂ® ???

One more thing: for the initial conditions I was managed to calculate the turbulent kinetic energy k with the formula: k=3/2(IU)2=0.9126* but I could not calculate the specific turbulence dissipation rate omega. Or better with the formula **omega=0.09k/betakinematic viscosity= 0.090.9126/0.1*0.0000155= 52989.67** I thought that this value could not be right, that is why I used a value of the bibliography omega=14.5. What do you think?

Thank you again!!!

#18

Hi @gholami!
I express myself wrong: the sweeping area is in this case:
** sweeping area = rotor height*rotor diameter**
And the rotor length is then the rotor height, right? that is to say the height of one blade.

@asmauos I will try to see your project today and try to help but IÂ´m not an expert!

#19

Sorry @gholami,
IÂ´m hesitating about the lift direction for flow direction +y (0,1,0). Of course it is in the x-axis but in which direction, positive or negative? +x or -x??
Thank you very much!

#20

Hi @gholami!
The lift direction is the direction of rotation and in this case for a airflow in the +Y direction the rotation direction is +X. Then the lift direction is +X. It is right?
Thank you very much!