Hi everyone how do you account the weight of turbine in flow simulation.

Basic setup for this type of problem:

Internal analysis

Add local rotation

Finding out what velocity it will rotate the turbine by applying a mass flow for the inlet flow and then iterate the flow until it will have a zero torque On the blades.

(I try to change the materials of the turbine so that the weight will change, basically if the turbine has a higher weight then the fluid should have a higher velocity to turn the turbine but based on my study weight does not affect the result, even if you do not assign materials to the turbine the calculation will still completed and give you a value. )

The material you choose for your solid geometry will never have any effect on your flow simulation. This software treats all solid geometry as FIXED and RIGID. There is no fluid-structure interaction and therefor no solid dynamics are calculated.

Your approach of trying to balance out the fluid pressure against the flow rate is interesting, I have no idea whether or not it is valid. It doesn't seem possible to me to have zero torque in this simulation, unless the flow rate is also zero.

Anyways in reality the weight of your turbine will mainly affect the frictional losses you have to overcome in your bearings, and the response time of your system to changes in wind speed. It should not ultimately determine the steady state angular velocity of your turbine, only the geometry of your blades will affect that.