How to control RPM with torque values

sungkue · October 23, 2023, 23:47

A typical MRF will take an RPM and use a formula like torque_z()@Blade to get a torque or power value.

I want to do the opposite.
I want to fix the Torque value to 25 and have the RPM calculated at that time, but I don't know how.
What should I do?

ghorrocks · October 24, 2023, 01:02

Sweep a range of RPM values with a series of simulations and you will get a Torque versus RPM curve. Then interpolate on the curve to find the RPM which gives you the torque you want.

sungkue · October 24, 2023, 03:02

Quote:

Originally Posted by ghorrocks

Sweep a range of RPM values with a series of simulations and you will get a Torque versus RPM curve. Then interpolate on the curve to find the RPM which gives you the torque you want.

That's not what I want.
I want the CFX, which is being calculated like a dynamic program, to adjust the RPM to match the power.

Gert-Jan · October 24, 2023, 04:57

This has been asked very often and I have never seen a solution. CFX is not as dynamic as you expect. It has no control mechanism with a feedback loop from generated torque to input RPM. I think mainly since there not easy damping available like in a PID Controller.

Better follow Glenn's approach.

Opaque · October 25, 2023, 12:55

Quote:

Originally Posted by sungkue

That's not what I want.
I want the CFX, which is being calculated like a dynamic program, to adjust the RPM to match the power.

What is exactly what you want ? Ansys CFX is a tool for achieving a goal, what is that goal?

The tool should be irrelevant to your goal.

October 23, 2023, 23:47	How to control RPM with torque values	#1
sungkue New Member sungkue oh Join Date: Oct 2023 Posts: 2 Rep Power: 0	A typical MRF will take an RPM and use a formula like torque_z()@Blade to get a torque or power value. I want to do the opposite. I want to fix the Torque value to 25 and have the RPM calculated at that time, but I don't know how. What should I do?

October 24, 2023, 01:02		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,933 Rep Power: 145	Sweep a range of RPM values with a series of simulations and you will get a Torque versus RPM curve. Then interpolate on the curve to find the RPM which gives you the torque you want. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

October 24, 2023, 04:57		#4
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,952 Rep Power: 28	This has been asked very often and I have never seen a solution. CFX is not as dynamic as you expect. It has no control mechanism with a feedback loop from generated torque to input RPM. I think mainly since there not easy damping available like in a PID Controller. Better follow Glenn's approach. sungkue likes this. Last edited by Gert-Jan; October 24, 2023 at 08:15.

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