URGENT! My Archimedes Screw turbine is not turning properly

jassonsee · August 5, 2020, 10:29

Hello there everyone, I wanted to ask if anyone knows why this problem is happening in Flow3D.

Right now im trying to simulate water flow through an Archimedes Screw Turbine for my project (an electricity generation system that has a turbine connected to generator to charge a 12V lead acid battery that is to be used in emergency situations when there is no electricity) but i don't understand why my turbine is turning in one direction then it turns the other way again when the simulation starts (i attached a gif). The turbine is positioned at an incline of 40 degrees and the velocity of water is 2.84m/s. Anyone knows how to solve the turning of the screw to make it turn steadily in one direction and not have it oscillate?

Flow Science Australasia · August 5, 2020, 20:27

Hi Jason,

One possible workaround to this would be to set a constraint on the rotational angle to prevent it from moving in the undesired direction. Here is more detail about this from the user manual:

"Users can also set limits for the object’s rotational angle in both positive and negative directions. The rotational angle (i.e., angular displacement) is a vector and measured from the object’s initial orientation based on the right-hand rule. Its value is positive if it points in the positive direction of the coordinate axis which the rotational axis is parallel to. The object cannot rotate beyond these limits but can rotate back to the allowed angular range after it reaches a limit. To set the limits for rotation, in Motion Constraints→Limits for rotation, enter the Maximum rotational angle allowed in negative and positive directions in the corresponding input boxes, using absolute values in degrees. By default, these values are infinite."

jassonsee · August 6, 2020, 13:14

Thanks for replying Eric! I have actually tried this method in this simulation. I actually set the negative direction to 0 and the screw would not move pass 0. However, the screw turned for awhile in the positive direction and then after that it turned backwards, but this time it turned back not more than the initial turn. Somehow the screw can still turn backwards and I'm not sure why.

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August 5, 2020, 20:27		#2
Flow Science Australasia New Member Eric Lemont Join Date: Aug 2020 Location: Brisbane, Australia Posts: 23 Rep Power: 5	Hi Jason, One possible workaround to this would be to set a constraint on the rotational angle to prevent it from moving in the undesired direction. Here is more detail about this from the user manual: "Users can also set limits for the object’s rotational angle in both positive and negative directions. The rotational angle (i.e., angular displacement) is a vector and measured from the object’s initial orientation based on the right-hand rule. Its value is positive if it points in the positive direction of the coordinate axis which the rotational axis is parallel to. The object cannot rotate beyond these limits but can rotate back to the allowed angular range after it reaches a limit. To set the limits for rotation, in Motion Constraints→Limits for rotation, enter the Maximum rotational angle allowed in negative and positive directions in the corresponding input boxes, using absolute values in degrees. By default, these values are infinite."

August 6, 2020, 13:14		#3
jassonsee New Member Jason Join Date: Aug 2020 Posts: 2 Rep Power: 0	Thanks for replying Eric! I have actually tried this method in this simulation. I actually set the negative direction to 0 and the screw would not move pass 0. However, the screw turned for awhile in the positive direction and then after that it turned backwards, but this time it turned back not more than the initial turn. Somehow the screw can still turn backwards and I'm not sure why.