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Old   June 15, 2016, 00:57
Default Impeller is not rotating
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junwee
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Reference pressure: 1 atm
Inlet pressure: 4360 Pa (Hydrostatic pressure)
Outlet pressure: 2657 Pa
Interface: Frozen Rotor
Impeller: 2656rpm

Hi guys,I am fresh to CFX but I have went through tutorials before carry out my project. The flow pattern is incorrect(should be looks like vortex) and I've found out the impeller is not rotating when i set it to stationary (0 rpm) and i get same result. May I know which part I did wrongly?

In fact, the outlet pressure should be higher than inlet.
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Old   June 15, 2016, 02:07
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Quote:
Originally Posted by kumar93 View Post
Interface: Frozen Rotor
I've found out the impeller is not rotating
If you want your impeller to rotate, you need to do a transient simulation.
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Old   June 15, 2016, 03:07
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Hi Maxim,I am sorry if my statement is not clear enough. What I mean is although I defined impeller as solid domain and 2656 rpm, it didn't shows the correct streamline and result. Regardless of what RPM i defined, the result is still the same. In other word, the impeller is not 'rotating' to generate higher pressure and velocity.

I don't really need the impeller to rotate in animation.
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Old   June 15, 2016, 03:22
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Are you drawing streamlines on Velocity? That may well show no twist. If you draw them on "Velocity in stationary frame" that might show what you are thinking of.

And: why have you defined the rotor as a solid domain? It should be a region cut out of the fluid domain as there is no need to model the rotor as a solid for most cases. Have a look at the CFX tutorial examples on rotating machinery.

Finally: As your volute design appears to be poor (there is a large gap between the impeller and volute casing) I would not expect much pressure rise in this design.
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Old   June 15, 2016, 03:37
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Hi ghorrocks. Thanks for your reply.

what do you mean by drawing streamlines on velocity? the inlet piping is close to the eye of impeller in order to ensure the water is fully absorbed by the eye.

Do you mind sharing the tutorial examples you mentioned above? Because tutorials i went through, impeller are usually defined as a solid domain.

I am sorry to have a such poor design as this is the only educational pump that I have.
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Old   June 15, 2016, 05:07
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Maybe these two threads could help you.
They deal with similar problems:
Simulation by ansys cfx for a ceilng fan balde
Axial Fan Timestepsize
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Old   June 15, 2016, 07:41
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Quote:
what do you mean by drawing streamlines on velocity?
You can choose which variable the streamline is integrated on. The default is velocity but sometimes Velocity in stn frame is appropriate.

Quote:
Do you mind sharing the tutorial examples you mentioned above? Because tutorials i went through, impeller are usually defined as a solid domain.
I have never seen a tutorial example where the impeller is a solid domain. They are always regions cut out of the fluid domain. Have a look at the CFX tutorials or the links Monkey1 quoted.
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