Wind Turbine Simulation
 

Hi, I am working on wind turbine simulation using a rotating reference frame. My aim is to calculate the power generated by the designed turbine. Here is what I have so far.

I have created a fluid domain with the rotor in the middle and a cylinder to simulate the rotating domain. Right now the rotor is subtracted from the domain while the cylinder is whole.

https://i.imgur.com/YZbXX8m.png

https://i.imgur.com/kZ5Z8EO.png

My first question is whether it is fine the way I have it currently configured or should it be some other combination?

Should I subtract the cylinder from the fluid domain and then the rotor from the cylinder?

Any help would be appreciated, Thank You.

Looks fine, you can indeed subtract the rotor from the cylinder. The cylinder and bulk domain should be separate bodies that do not overlap; is that currently the case?

Currently they overlap as I wasn't sure. I will fix that.

Furthermore as I understand to calculate power I will multiply the rotational velocity given to the moving frame with the torque that is felt on the rotor. Is that correct?

Ok, if you subtract the cylinder from the box, and keep the cylindrical body with the rotor, all should be fine.

You can calculate the torque using reports > forces and then select moments, setting the right axis origin and direction, and then calculate the torque on the turbine indeed. After that, indeed multiply by the 2*pi*N (rps), and you have the power.

Good luck! Cees

Just an update. I made the mesh shown below, used sphere of influence in body sizing so that most of the elements are in the middle.

https://i.imgur.com/sSJhXOo.png

https://i.imgur.com/m9Ovswe.png

I feel that the elements might not enough but considering the computer I have access to currently this is the best I can do. I hope to make a finer mesh once I have access to a more powerful computer.

In fluent I set the time to transient, k-w SST for turbulence, frame motion to the cylinder about x-axis at 37.5 rad/s. Inlet velocity set to 5 m/s and pressure outlet. Set the flow time to 5s with 50 intervals each 0.1s. The solution is being calculated as we speak. Hope it works out.

why is there a very dense mesh region far away from the cylinder? I understand you are limited in the mesh size, so it seems to me it is important to be efficient in refinement - that clump of cells on the upper right does not look very efficient to me. Maybe you can improve the mesh, making sure:

1) the mesh is fine close the the blades, and cruder far away
2) the domain is predominantly filled with hexahedral/polyhedral elements (hexahedral will be though/impossible near the impeller, but surely applicable to the bulk of the domain)

I changed the mesh to be a bit more concentrated around the cylinder.

A view of the new mesh
https://i.imgur.com/hSS2OxO.png

Sliced View Along the XZ Plane

https://i.imgur.com/cW75g0U.png

Sliced View Along the YZ Plane

https://i.imgur.com/D8NXjt1.png

Afterwards I ran the calculations and it came with the following moment report.
https://i.imgur.com/CkpciZ1.png

But according to this the turbine would generate only 0.090707897*37.5 = 3.40 W
Power available = 0.5*3.1415*(0.4^2)*(5^3)*1.225 ( 1/2 * pi * r^2 * v^3 * rho) = 38.48
Which would correspond to a coefficient of performance of 8.839% which seems quite low. Is this right considering the blade shape and the small size and speed or am I doing something wrong?

Looking at the results in CFD-Post I think I might have screwed up the mesh interfacing. I am going to try again this time interfacing each face individually.

https://i.imgur.com/jy0hYPS.png

Similar Problem
 

I am doing my final year project (Mechanical engineering, be Hons) on ducted wind tubines. I am mainly interested in increasing the power generation (obviously). I have got also some data from an actual turbine built by a company;such as power generated at each wind speed in the venturi.

I managed to run a cfd model on this and got pretty close results to what the company achieved. Using their data (power generated and power coefficient) and my cfd results, I managed to find the pressure difference caused by the turbine.

The study is a 2d study at first which later on i will be doing also a 3d and instead of the turbine i set a porous region.

My question is even if i do get this right, and lets say i change geometry or some other stuff to increase the mass flow rate, how can I know the new pressure difference caused by the turbine? Because, Based on what I think, turbines would obviously give different pressure difference at different rotational speed (that is how it generates different power at different speed).

Pretty much, I am interested to say that the power generated is increased by certain percentage etc.

Any guides ?

hammar, why the fluid not flow indeed rotating body or blade ?