Hello OpenAFPM community!
First, I would like to thank all the OpenAFPM team for these amazing tools !!
I am currently simulating a generator for a 0.8m diameter small wind turbine for an educational wind tunnel. The wind turbine has been constructed already.
I would like to simulate the generator to get its theoritical parameters, however, the openafpm tools have a limitation for the rotor diameter (1m20).
At the moment, i bypassed the limitation by giving biased Cp and Lambda to compensate the smaller radius of my wind turbine in terms of power and rotational speed according to the following formulas :
Simulated Turbine Radius : R=0.6m
Real (') Turbine Radius : R'=0.4m
Cp=Cp'/K (to compensate the smaller area of the equivalent rotor radius R'=0.4m )
(K=(R^2)/(R'^2)=2.25)
Omega'=(Lambda'*Vw)/R'
Lambda=(Omega'*R/Vw)
Which theoritically gives a 0.8m_equivalent_power 1.2m rotor spinning at the same speed as the 0.8m (so with a higher TSR).
To match the Cp/Lambda curve, I divided the CP values by K.
According to you, are these tricks enough to bypass the limitation or are there other factors playing that makes the corresponding generator senseless?
Would it be possible to move the rotor radius limitation to 0.4m ?
Many thanks for your help and feedback,
Adrien
PS : it would be great to be able to insert LaTex equations via the text editor
Hi Adrien
I'm sorry that I can't confirm that your workaround is valid - I don't have the aeronautical engineering knowledge to do so, and I suspect that you have moved forward since your post was from 2020, but I wanted to mention that I have a requirement to model a Vertical Axis Wind Turbine that I would like to be able to use the tools as the generator design is taken from Hugh Piggott. Again, I cannot do so because the tools are setup to assume a horizontal wind turbine.
I think that it might be sensible to change the tools to allow the power characteristics of a generic turbine as the input parameter rather than aaerodynamic parameters for a horizontal wind turbine. This would make the tools useful for Vertical Axis Wind Turbines and Hydro-power Turbines. Such a change could allow designers to make use of these excellent tools to design generators for novel turbines.
I also have a requirement to model a very small generator (60-100w). Again, removing any limits at the lower end of the scale would be useful. Someone might say that for small generators it would not be necessary to build a generator to Hugh Piggott's designs because there are many commercially available motors and generator that might be used, but in my case I have limited space and a small flat generator would be more suitable. While such items are available to purchase, it is certain that their outputs will not be as their manufacturer claims, and so I might need to buy two or three items before finding one that does meet the required output.
I hope you made progress with your project.