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Propeller free spinning RPM estimation
Dear all,
I am trying to use Qblade to estimate what speed would a given propeller connected to a BLDC motor spin at a given strictly due to windspeed (windmilling propeller)
So far I have created a 2-blade UAV propeller following the propeller data found in https://m-selig.ae.illinois.edu/props/volume-2/propDB-volume-2.html#NR640
I then scaled it according to my required measurement specification and ran BEM Analysis for ROTOR at a given wind speed(eg. 30m/s)
From the simulation I am able to obtained the Torque-RPM curve of the propeller and compared it to the motor’s Torque-RPM curve to obtain the equilibrium RPM the propeller will spin at.
May I ask if my approach is correct or is there a method to test this out — to find out the propeller/motor RPM at a given wind speed
My apologies for any inconvenience caused
Best regards,
QJ
I manage to browse upon this post which seems to be able to help me out.
https://qblade.org/qblade-forum/topic/how-to-predict-rotor-rotational-speed/
However, I am unsure on how to do that simulate as seen in his Fig.1 & 2 as well as including a generator for my case.
This is my first time using this and would appreciate any help
Hi QJ,
the approach that you have outlined, based on the rpm/torque curves for a specific windspeed, should work.
If you want to test this out in a time domain simulation you need to:
- setup the LLFVW aerodynamic modelling for the propeller
- define a structural model for the rotor so that mass/inertia information is available, you can set the tower height to zero and not use a tower file
- provide the generator torque, for examle by using an External Loading File (using HUB as the sensor name)
By carrying out the time domain simulation you can then observe at which equilibrium RPM the proepeller will operate for a given motor torque and how much thrust is generated.
BR,
David
