[mrshives]

Ansys will give you the shaft power. This is the mechanical power at the rotor shaft before any gearboxes, generators etc. Some power is lost in each of those components. Obviously, you need to include the efficiency of each of those components if you want to compare to the generator output power. Just draw a diagram of the rotor and power take-off components and this will become really clear really quickly for you.

[hossam elbakry]

thanks for your reply,
and in addition to your words, an efficiency of the turbine rotor as mentioned in the

following equation:
The rotor efficiency is divided into three parts
ηrotor =ηwake x ηtip x ηprofile
where “wake” indicates the loss because of rotation of the wake, “tip” the tip loss and “profile” the profile losses.

should be included with the generator, invert-er and gearbox efficiency.

an i right?

[hossam elbakry]

hi all,
is there any way to design the twisting and the chord of wind turbine rotor?, by excel file or something similar.

[ghorrocks]

That sounds like basic turbomachinery design question, not a CFX question. Try a turbomachinery textbook or training course, or turbomachinery design software (like turbogrid).

[hossam elbakry]

but the required not to know how to design it or how to draw it,
the required is to know what is the effect of tip speed ratio variation on the twist angle and chord length.

[ghorrocks]

Twist angle and chord length are blade design parameters - so please refer to post #44.

If I have misunderstood your question then please explain it more.

[Dickzperm]

hii cfd master in here

i got the problem about wind turbine simulation with horizontal axis, three blade rotor, with wind speed 5 m/s, the variation of rpm from 1500-2500 rpm (refered from the curve of cp), the simulation is converged BUT the fail is the result of torque is increasing during the rpm is increasing,
can you help me, i have already change every boundary condition but the result is same.

[Dickzperm]

could you give me the detailed about CEL ?
i have problem with the result of torque, that is increasing during increasing angular velocity...

[ghorrocks]

The torque increasing with speed could be real or it could be numerical error.

If it is real it is saying the maximum torque point is at a faster speed than you are currently modelling. This is quite possible.

If it is numerical error then you need to do validation and verification checks on your simulation. Here is a starting point: https://www.cfd-online.com/Wiki/Ansy..._inaccurate.3F

[RAKESH KUMAR]

Hi,
I want to simulate a model of Darrieus turbine with 3 helical blade using airfoil profile of NACA 4415 in Ansys CFX. I want to calculate torque of turbine with respect to angle of rotation and power with respect to torque. Also want to calculate lift coefficient and drag coefficient vs angle of attack.
Please any help me...

[ghorrocks]

Quoting the FAQ (https://www.cfd-online.com/Wiki/Ansy...ible_answer.3F) - "Dont ask over broad questions e.g. "How do I simulate a 4-stroke engine". Nobody is going to type out fifty pages of guidance. They have better things to do."

Do the tutorials, do some training, use the software and get familiar with it, do some benchmark cases to check you can get accurate results.

[Aye Mya Moh]

Hi Guys,

I am CFD beginner.I have a problem about the simulation of hydro kinetic axial flow turbine which is similar to horizontal axis wind turbine.My problem is error in result file that I cannot calculate the value forces, torque of the blades.
The error massage box is " Force of fluid 'Fluid1' is not available in the file and cannot be calculated on geometry' / DATA READER/CASE:Case CFX/BOUNDARY:Rotor Blade Default.

How do I calculate the results of blade and then help me to find my errors.

Thanks!

[ghorrocks]

To calculate torque the results needs pressure, wall shear stress and the mesh. If any of these are missing from your results file you will not be able to calculate the force (or torque). They are in a results file by default, but might not be in a transient results file (.trn file) - you will have to add them.

[urosgrivc]

hy Aye Mya Maw:

Very common beginers mistake is also to include the solid wind turbine in the CFD simulation (it is not needed if you are not doing a coupled cfd-structural analisiys) if you did include it make sure to look at torque (on the FLUID side of the conection) as the solid side doesent contain the fluid data which Glenn mentioned which is needed for the calculation of torque

[Aye Mya Moh]

Hi
Ghorrocks,

Thanks for your reply and next time I will post CFD questions on the forum.Sorry for my mistakes.

Thanks
Aye Mya Moh

[Aye Mya Moh]

Hi
urosgrivc,

Thanks for your suggestions and I am doing flow analysis of hydrokinetic turbine which has three blades and power output is 200W.And then I am trying to compare theoritical and numerical analysis of hydrokinetic turbine.So in my simulation contain two domains; rotating domain and stationary domain and three interfaces.I set fluid to fluid domain.It is correct or not. Now I am trying my simulation by watching tutorials.Please suggest me and point out my error. Can you show me the links or tutorial files.

Thanks
Aye Mya Moh

[urosgrivc]

ok so that sounds about wright, but you should be able to get torque from the simulation by default, I dont know much about your setup so cant help at this point some figures ans seting would help

[Gert-Jan]

You get a message like: "Force of fluid 'Fluid1' is not available in the file and cannot be calculated on geometry' / DATA READER/CASE:Case CFX/BOUNDARY:Rotor Blade Default."

I get messages like these when something is missing, names have changed, or whatsoever. So, my questions are:
- what file is loaded? Is it a .res-file or a temporarily .bak-file that has been deleted?
- did you read a .cst-file to automatically create a report? If so, are the names of Fluid1 or the boundaries (e.g. Rotor Blade Default) in the -cst-file exactly the same as in your setup?
- how do you calculate the force? Do you use the calculator? That would be the most easy way:

1) Load your .res file in Post and open the calculator .
2) select the torque you need
3) select the blades
4) press calculate, et voila.

If that doesn't work, then your file is corrupt.

[hellboy]

hey, did you got your solution for your wind turbine problem , because i also want to do a analysis of a wind turbine rotating at different wind speed but wind rotates the blades can you help me