I have the same question.
I appreciate that this original post is 3 years old, but I have been unable to find the solution to how to find the resistant force of the fluid (air in my case) as the propeller starts to rotate.
With my propeller being more of a turbo-fan style (with 10 blades making up the fan assembly), I thought I could model a single blade, get the drag force value, then multiply by 10... But this would not account for the effect of the airflow from the preceding blade upon the following blade whilst is rotates.
So, I am left in the same situation as you....
"The goal of my analysis is to determine to the torque on the fan blade as a result of it coming in contact with the air around it. In other words, the fan is rotating due to the torque provided by the motor, but there must be a resistance from the air it contacts while rotating...this resistance should provide a somewhat negative torque to the torque provided by the fan motor.
I'm trying to determine this negative/retarding torque..."
Did you find the solution? and could you share, or if anyone else can help?
David (same name)
You are looking for cyclic symmetry. Flow sim has this but it has some restrictions due to the nature of the code - I would say more but I have not used it so the nature of the restrictions I am not familiar with. However, I suspect it would be only available on a 1/4 symmetric segment of the rotor and the cut planes sections would need to be the same but maybe not. You can use global rotation. What is the solidity of your rotor? Maybe an image? I would call what you are looking for the "no load fixed loss".