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Chalghoum April 7, 2014 07:21

centrifugal pump
 
Dear all,





I Chalghoum Issa PhD student

I work on the study of transient flow in the inner centrifugal pump.
I make a design pump using the Vista CPD tool then I make a mesh of the volute automatically and make a mesh impeller by Turbogrid tool but when I make a Toy of the pump ansys cfx solver manager the results of the parameters displayed speed and pressure of the moment equations and mass are a dimensional .
when I try changing the pressure and velocity on the pump ( impeller and volute ) ansys cfx displays only the impeller and does not display the volute (in order turbo mode).

my questions are :

is that the mesh separate from the centrifugal pump ( the impeller with turbogrid ) and ( volute with control mesh ) causes problem for the results then displayed on ansys cfx if so what are the tools meshes of a centrifugal pump the most accurate .

shown how the evolution of the relative velocities and pressure of centrifugal pump ( impeller and volute ) and shown how the evolution of the height function of mass flow rate .

I needs these results as soon as possible.

please Help me

mail :chalghoumissa@yahoo.fr

brunoc April 7, 2014 09:26

Do you mean that the results are non-dimensional? Are you talking about the automatic report created by Post? If so, those reports do create some non-dimensional variables, but you can skip them and do your own post-processing.

Quote:

is that the mesh separate from the centrifugal pump ( the impeller with turbogrid ) and ( volute with control mesh ) causes problem for the results then displayed on ansys cfx if so what are the tools meshes of a centrifugal pump the most accurate
The only problem is if you try to enable Turbo-Post on the volute domain, since that won't have the regions expected by Post. If you want to use Turbo-Post, just uncheck the box for the volute domain.

The mesh created automatically by WB should be fine for a first run, but you should go back to it and check element sizes and boundary layer settings. From experience, that mesh tends to be a bit too coarse to detect fine details on the flow.

Quote:

shown how the evolution of the relative velocities and pressure of centrifugal pump ( impeller and volute ) and shown how the evolution of the height function of mass flow rate
Run different simulations changing the mass flow you're using as a boundary condition and measure the height for each result. Then plot the values on Excel.
Or use the built-in capabilities on WB to do those for your. Check the CFX tutorials to see how to do that.

Chalghoum April 7, 2014 14:12

Thank you Bruno

I use Turbopost and I deactivated the volute but when I posted the request destribution of pressure and velocity along the impeller and volute, CFD position displays only the destribution for the impeller.

what are the steps necessary for Ansys cfx shows the distribution of velocities and pressures in the centrifugal pump (impeller and volute)

what is the command to use to make my own post-processing.

Chalghoum April 7, 2014 14:19

you can contact me by email or skype to understand my problem and allows me to help find a solution

brunoc April 7, 2014 14:31

No, Turbo-Post is only for bladed machines, so you can't use it with your volute. If you want to plot distributions of anything in your volute, you're going to have to do that manually.

You should create planes going through the regions you want, then color them according to the variable you want to see. For things such as height/pressure variation, create expression to calculate them or use Post's built-in calculator.

This is all covered is the tutorials that come with the software. If you're in a hurry, you should invest your next few hours trying some of them. After just a few (which you can cover in an hour) you'll grasp the idea of how the software works and be able to do everything yourself (create planes, expressions, use the calculator, etc).

Chalghoum April 11, 2014 07:26

thank you

I make an example of a centrifugal pump with ansys cfx 14.5
. my question is how to vary the mass flow rate and height
formula for the mass flow rate and height in ansys cfx?
what is the command to the given destribution speeds and pressure in the centrifugal pump (impeller and volute).
because I use the turbo control and I watch destribution speeds and pressure alone in the impeller.

its main line of my programe on cfx solver please what are the errors that I can fix.
Option = Steady State
EXTERNAL SOLVER COUPLING:
Option = None
DOMAIN: Impeller
Coord Frame = Coord 0
Domain Type = Fluid
Location = Entire Passage
BOUNDARY: Impeller Blade
Boundary Type = WALL
Frame Type = Rotating
BOUNDARY CONDITIONS:
MASS AND MOMENTUM:
Option = No Slip Wall
END
WALL ROUGHNESS:
Option = Smooth Wall
BOUNDARY: Impeller Hub
Boundary Type = WALL
Frame Type = Rotating
BOUNDARY: Impeller Inlet
Boundary Type = INLET
Frame Type = Stationary
BOUNDARY: Impeller Shroud
Boundary Type = WALL
Frame Type = Rotating


BOUNDARY: Volute to Impeller Side 2
Boundary Type = INTERFACE
BOUNDARY: Volute Outlet
Boundary Type = OUTLET
Location = Outlet
BOUNDARY CONDITIONS:
FLOW REGIME:
Option = Subsonic
END
MASS AND MOMENTUM:
Mass Flow Rate = 36 [kg s^-1]
Option = Mass Flow Rate
TURBULENCE MODEL:
Option = k epsilon
END
DOMAIN INTERFACE: Volute to Impeller
Boundary List1 = Volute to Impeller Side 1
Boundary List2 = Volute to Impeller Side 2
Interface Type = Fluid Fluid
INTERFACE MODELS:
Option = General Connection
FRAME CHANGE:
Option = Frozen Rotor

What are the boundary conditions (impeller and volute) necessary for the centrifugal pump.
I have a problem cancerne option "pitch" I take it as "none" but an error massage appears.

Chalghoum April 11, 2014 07:28

please can you help me

ghorrocks April 11, 2014 08:03

Making functions of flow rate and other stuff is very simple - as Bruno said it is covered in the tutorials and you would be wise to do them.

Regarding boundary condition choice: Read the best practises guide on turbomachinery in the CFX documentation. It has a discussion on boundary condition choice.

Chalghoum April 11, 2014 08:33

thank you my freind

I do all my efforts and I read the documentation of ansys cfx but I can not find an example that addressed the centrifugal pump (impeller and volute).
I find an example of interrese simulation of a centrifugal pump to help me in my project.

please sent me an example of a centrifugal pump.

ghorrocks April 11, 2014 08:47

I do not have any examples of centrifugal pumps and I do not have time to do one for you.

Of course you will not find an example of your exact case in the CFX examples. But some examples use functions to make boundary conditions variable, even if they are not exactly what you are trying to do. They introduce the general concept and you have to adapt it for your case.

Abou ali April 11, 2014 08:51

Quote:

Originally Posted by Chalghoum (Post 485423)
my question is how to vary the mass flow rate and height
formula for the mass flow rate and height in ansys cfx?

Hi;
The easiest way to get the pump characteristic H=(Qv) is to change manually the value of the masse flow rate in the CFX-Pre then calculate the total head in CFX-Post.
If you want to do it automatically, you can use the ANSYS DesignXplorer.

brunoc April 11, 2014 08:53

Quote:

Originally Posted by Chalghoum (Post 485439)
thank you my freind

I do all my efforts and I read the documentation of ansys cfx but I can not find an example that addressed the centrifugal pump (impeller and volute).
I find an example of interrese simulation of a centrifugal pump to help me in my project.

please sent me an example of a centrifugal pump.

Your problem is not related to simulating a centrifugal pump, your problem is related to using the software. The tutorials will help you on that. So study the tutorials. They are there for a reason.

Start on the first one (static mixer) and keep doing each one of them until you reach the one about the axial turbine (#14 on CFX 15). This one will show you how to work with Turbo-Pre and Turbo-Post. Only skip the ones that talk about multiphase or reactions if you don't have a license to run cases like that. And if you can, keep doing the other ones too.

Even if they don't seem related to exactly what you're doing, the tutorials will teach you the best ways to work with CFX and also give you some best practices, including post-processing your results.

Chalghoum April 11, 2014 09:11

thank you very much my friends for the best answers

I do not ask of my project work centrifugal pump but I asked to help by a month tutorial to guide me everything.

if you have a tutorial or idea, thank you, if not yet, thank you for your help
good luck to everybody

brunoc April 11, 2014 09:17

Quote:

Originally Posted by Chalghoum (Post 485455)
I do not ask of my project work centrifugal pump but I asked to help by a month tutorial to guide me everything.

Quote:

Originally Posted by ghorrocks (Post 485444)
Of course you will not find an example of your exact case in the CFX examples. But some examples use functions to make boundary conditions variable, even if they are not exactly what you are trying to do. They introduce the general concept and you have to adapt it for your case.

Quote:

Originally Posted by brunoc (Post 485449)
Even if they don't seem related to exactly what you're doing, the tutorials will teach you the best ways to work with CFX and also give you some best practices, including post-processing your results.

There isn't much I can add.

Chalghoum April 11, 2014 09:26

thanks brunoc

Chalghoum April 12, 2014 06:40

centrifugal pump
 
I make a simulation of a centrifugal pump in ansys 14.5 and when I run the configuration table of the mesh is shown in (out.file)

a parameter in this table (Exp.Factor) appear with an exclamation point.
please help me to correct this factor

ghorrocks April 12, 2014 06:53

The output file is not attached. But the table you are referring to is looking at the mesh quality. Note that it is just a guide, your simulation might be more or less sensitive to mesh quality.

To improve mesh quality you need to be more careful in your meshing package.

Chalghoum April 16, 2014 04:22

Thinks friend

I have a message containing errors in Pitch change option
"In Analysis 'Flow Analysis 1' - Domain Interface 'S1 to R1': Pitch Change option 'Automatic' is not valid if side 1 or 2 of the interface has a 360 degree or greater pitch angle, zero radius, mesh faces normal and parallel to the rotation axis, or mesh faces at the hub curve (low radial or axial position) which are thin in the radial or axial direction"

how can fix in ansys cfx because I automatically maillaige using ANSYS ICEM CFD.
what are the technique maillaige a centrifugal pump the more precise

ghorrocks April 16, 2014 07:37

The error message is very clear. One of the problems it discusses is happening, so you have to work out which one and fix it.


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