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Modelling and Simulation of a H-shaped VAWT
Dear reader,
Is it possible to design a H-shaped VAWT using QBlade? For my assignment, I need to design a H-shaped VAWT. Therefore, I need to choose/design an airfoil first, and thereafter design a H-shaped VAWT. I also need to model and simulate this design, as I need to meet some requirements, such as a power output of 500W.
I only can find information and guidelines regarding HAWT, helical shaped VAWT and troposkien shaped VAWT… So, is it actually possible to model and simulate a H-shaped VAWT?
Kind regards,
Tim
Hi Tim,
H-shaped VAWTs can of course be modeled, just create a blade design with a straight blade.
BR,
David
I have a question regarding the tutorial described in “Qblade Guidelines v0.6”. Obviously this is the older version, as I’m using the newest QBlade version, 2.0.5.2a. Somehow, I’m doing something wrong as I don’t get any results for the Power graph and Thrust graph.
I’m wondering where to find and change the Weibull Settings within the “Turbine BEM simulation” submodule. This is shown in figure 3.7 of the PDF file “Qblade Guidelines v0.6”.
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Hi,
to enable output in the graphs simply double click on them and choose parameters to plot. The “Cruise Velocity” variable shown in your screenshot is only avaliable for propeller simulations and thus not output is plotted.
Regarding the “Weibull Graphs”, these are not part of the newest QBlade release.
BR,
David
Dear David,
As I’m trying to design a VAWT for Mars, the following parameters are set:
Re = 7500
M = 0
NACA 0002.
No other parameters are touched.
However, when I’m about the extrapolate it to 360, and analyse the lift-drag ratio, it becomes zero. Which in the end produces a negative power coefficient. Why is it zero? If I use other symmetrical airfoils, for example NACA 0018, the ratio becomes zero as well. I’m using the Viterna method.
Best,
Tim
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Hi Tim,
the glide ratio is not zero, it only appear so in the graph. The issue is that for the AoA’s in the region of 180° the drag coefficient approaches zero so the glide ratio tends towards infinity. This is why the glide ratio appears to be zero in the plot. This is btw. fixed in the upcoming release where the minimum drag at 180° AoA is limited to not approach zero as much.
In your project file it seems that the rotor you are simulating has a very high solidity and the DMST algorithm often has problems correctly predicting performance for high solidity rotors. So I would suggest to use time domain LLFVW simulation to evaluate the rotor performance.
But anyways, with a RE of 6500 the glide ratio will be quite small so the maximum CP is expected to relatively low.
BR,
David
Dear David,
I’m working on my project. However, I still didn’t manage to obtain a proper power coefficient. I reviewed your tutorial, described in “Qblade Guidelines v0.6”. I wanted to look after what went wrong with my simulations. However, if I’m doing your tutorial, I didn’t manage to get any power output and thrust. See for picture “No Power and No Thrust”, which is my simulation. But in the end should look like the picture “What it should look like”, which is from the QBlade guidelines v0.6.
What am I doing wrong?
Kind regards,
Tim
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Hi,
I think you still have the issue of the variables shown in the graphs to which I commented already above:
to enable output in the graphs simply double click on them and choose parameters to plot. The “Cruise Velocity” variable shown in your screenshot is only avaliable for propeller simulations and thus not output is plotted.
Regarding your turbine simulation with a fixed rpm of 200 you are operating at tip speed ratios between >200 and 10, so youre most likely operating in the negative power coefficient range. Try settng the transmission to “optimal” and/or change the rpm range.
Best,
David
Dear David,
Of course. Sorry, I missed your answer.
I have a new question. Is there any chance to calculate the annual energy production (in kWh/year) in QBlade based on Weibull parameters (or on a different way)? You said that the “Weibull Graphs” are not possible anymore, but is it still possible to fill in the weibull parameters somewhere?
Kind regards,
Tim
Hi Tim,
no, unfortunately not. But the AEP assessment can easily be ontained from a spreadsheet based on the power curve (power vs windspeed) obtained from QBlade, and the wind probability distribution (probability vs windspeed) calculated from the Weibull distribution.
The probabilities can be obtained from this website or you can also calculate the yourself with the formula shown there.
BR,
David
