[cheap_person]

Hi there!!!
Hope you are doing good today.

I'm trying to make a performance map by performing a cfd simulation of an impeller. it is performing using cfx, turbo mode.

A negative sign is used to change the direction of rotation of the impeller.
But, I am using an expression (speed, as an input parameter) to provide rpm. but i am keep failing to get similar result with negative sign.

I tried the following combinations with negative sign:
1. - speed , 60000 (negative sign with expression speed while putting boundary condition, keeping value positive in input parameter)
2. speed , -60000 (positive sign with expression speed while putting boundary condition, keeping value negative in input parameter)
But the arrow of the direction in pre-processing doesn't change.

Problem: Now I am unable to provide correct direction of rotation to my impeller. it is revolving in opposite direction.
what is the solution?

sending positive vibes...!
cheap person

[ghorrocks]

To do this you need to:
* In CFX-Pre define the rotor speed as a Workbench input variable. I think the speed is then defined along the rotation axis you define, so a negative speed should go the opposite way (but check this, I am not sure).
* In Workbench you need to define the value of the speed parameter. This should accept positive and negative values, and that should reverse the direction of rotation.

[Opaque]

Originally Posted by cheap_person

Hi there!!!
Hope you are doing good today.

I'm trying to make a performance map by performing a cfd simulation of an impeller. it is performing using cfx, turbo mode.

A negative sign is used to change the direction of rotation of the impeller.
But, I am using an expression (speed, as an input parameter) to provide rpm. but i am keep failing to get similar result with negative sign.

I tried the following combinations with negative sign:
1. - speed , 60000 (negative sign with expression speed while putting boundary condition, keeping value positive in input parameter)
2. speed , -60000 (positive sign with expression speed while putting boundary condition, keeping value negative in input parameter)
But the arrow of the direction in pre-processing doesn't change.

Problem: Now I am unable to provide correct direction of rotation to my impeller. it is revolving in opposite direction.
what is the solution?

sending positive vibes...!
cheap person

The "arrow" in the user interface is for the "axis definition", not the rotation direction.

On the creation of the performance map, have you tried the "operating points" functionality? Performance maps for turbomachinery models have been a built-in functionality for a few years.

[cheap_person]

Originally Posted by ghorrocks

To do this you need to:
* In CFX-Pre define the rotor speed as a Workbench input variable. I think the speed is then defined along the rotation axis you define, so a negative speed should go the opposite way (but check this, I am not sure).
* In Workbench you need to define the value of the speed parameter. This should accept positive and negative values, and that should reverse the direction of rotation.

problem solved using first point, warmly thank you so much sir Glenn!!! 😁

I don't know should I ask for it here or not.
"Do you have Instagram id" I want to connect to you there.
I will not ask any simulation related question or any question.
In future if I do, surely you can block me there.

sending warm regards...! ('◡' )
cheap person

[ghorrocks]

Feel free to PM me if you are sending me a message. Just put CFD questions on the forum, as my footer requests.

[cheap_person]

Originally Posted by Opaque

The "arrow" in the user interface is for the "axis definition", not the rotation direction.

On the creation of the performance map, have you tried the "operating points" functionality? Performance maps for turbomachinery models have been a built-in functionality for a few years.

However, the problem is solved.
But no, the arrow which I'm talking about it does tell the direction of rotation.

Here in following image, the white line shows direction, and black line shows the axis of rotation.

click here


Sorry not, I've not seen operating points in cfx yet! 😅

But I'm so amazed to know about it, I've just searched it on google.
Chapter 13: Operating Maps and Operating Point Cases

Thank you so much sir opaque for your reply.
I learned a new thing today!!! 😁

sending positive vibes...! (´◡` )
cheap person

[Opaque]

Originally Posted by cheap_person

However, the problem is solved.
But no, the arrow which I'm talking about it does tell the direction of rotation.

Here in following image, the white line shows direction, and black line shows the axis of rotation.

click here

I see, you are using the Turbo Mode in the pre-processor. I do not recall seeing that arrow in General Mode.