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Cut in wind speed and power rated
Hello, I’m a rookie in Qblade.
I attempted to simulate HAWT with the goal of determining the value of cut in speed and power rate based on my design
Can somebody here tell me how to find the result of the aim?
Hello FCMega,
there is no single answer to what rated power and cut-in wind speeds are working for a particular wind turbine rotor.
Both, cut-in and rated power, are design choices and also depend on the specific wind conditions at the turbine site, and other parameters, such as generator choice etc…
To get started you can run a few steady-state BEM simulations. The Turbine BEM Module allows you to create power curves for your rotor design by setting cut-in, cut-out and the rpm curves.
BR,
David
Thank you for your response. I have tried the steady-state BEM simulation. The Cp graph obtained decreases with TSR. Please correct me, which parameter might have caused the error?
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Hi,
from the negative cp curve that you are showing it seems like your rotor blade design operates more as a propeller that is adding energy to the flow rather than extracting it.
The blade design module includes functionality for optimizing the chord and twist distribution of a rotor blade. Try to optimize your design and you should obtain positive power output!
BR,
David
Alright David, I’ll try to iterate again. Do you have any recommendations for the chord and twist of a rotor blade for a 2-meter diameter rotor?
Hi,
there is a blade chord and twist optimization feature included with the blade design module which can automatically set the values for you, given a design tip speed ratio.
See the attached image.
BR,
David
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Dear David,
Need help, in the RPM setting, only fixed RPM is possible (as seen in Figure 1). Consequently, for the aero Power vs RPM graph, only values at the same RPM are obtained (Figure 2). What is your advice for this issue, David?”
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Hello,
for turbines that dont have a structural model defined only a constant rpm can be prescribed, since no controller can be included due to a lack of inertia properties for the rotor.
If you want to generate a power curve you can do so by creating a simulation for each operating point, where an operating point is defined by a combination of windspeed, rpm and collective pitch angle.
Alternatively, if you want to simulate a variable rpm during a single simulation with an aerodynamics-only definition of a turbine you can use a “Simulation Input File” to prescribe rpm over time. See the secttion Turbine Behavior in the documentation.
BR,
David
Thank you for the guide, David.
I also have a question: why does changing the angle of attack, produce the same torque vs wind speed value? Is my understanding of the angle of attack correct? angle of attack is a twist at the root. whereas the root area uses a circular cross-sectional profile.
Hello,
the angle of attack is the local angle between the chord of an airfoil cross section and the incoming wind vector, this is the alpha angle the image below:
The beta angle in this image is the local twist (or build) angle of the airfoil section.
The pitch angle of a rotor rotates the whole blade (all airfoil sections) by this angle.
BR,
David
