# Contra-Rotating Windmill Simulation

#1

I’m planning to simulate Contra-rotating propellers for windmill and wanted to check how SimScale can be useful in this use case. Here are few questions before I start project.

1] Does SimScale Wind flow in tunnel rotate the propellers based on the wind speed as pressure is exerted on the blades automatically or I have to set the RPM values explicitly (don’t know the values from real world scenario)?
2] Would it provide how much torque/rpm being generated at give wind speed?
3] Would I get different power output, if we add some kind of load on the propellers e.g. generator or something similar?

Any guidance on this kind of simulation would be highly appreciated as I’m completely newbie here.

Thank you.

#2

Greetings,

SimScale has 2 different approaches for rotating zones, MRF (multi reference frame) and AMI (arbitrary mesh interface), both of which require an angular velocity as input, therefore:

• 1: You do have to explicitly set them as an input;
• 2: RPM values would be the ones that you input. As for torque, yes, you can calculate the value based on forces and moments. An interesting discussion is in this thread;
• 3: With these restrictions, I think the easiest way to do this would be to estimate the angular velocity of the propellers when generators or other equipment are attached.

SimScale released a webinar on propellers if you want to take a look.

/Ric

#3

Thank you for your response @RecardoPG
Unfortunately I do not have any values, which I can put in for simulation. My understanding was, If we place turbine in wind flow, it will automatically start rotating it based on the wind speed and give the values for torque and RPM, so power can be calculated.
If I give RPM values, then I’ll never be able to know how the Propeller will behave or respond to wind naturally and what power I’d be able to extract from the Wind.

My intention is to see how the Turbine behaves in the flow and what would be it’s output at particular wind speed. Is it possible?

#4

Sadly it wouldn’t be possible to transform wind’s kinetic energy into movement for the windmill . What kind of windmill exactly are you looking for? Is it like those from the Netherlands? Or those attached to electric generators?
Also, does this kind of windmill have speed limitations? Most of them have some sort of limitation because otherwise they end up collapsing. If this is the case and you can determine the velocity-span, you could try to run multiple simulations for the range of the angular speed.
Just a thought though.

#5

It’s new breed of Windmill and will be attached to Electric generators. These windmills extracts maximum energy from the wind up to Betz limit.
No they won’t topple/collapse and don’t have any upper limit on speed/rpm. Also they virtually don’t have Gearbox too. In short they are new Windmills, which solves all the issues faced by current production windmills.

#6

Have a look on these open articles, I think they might come in handy:

• Wind turbine control in computational fluid dynamics with OpenFOAM;
• 3D modelling of a wind turbine using CFD.

/Ric