Propeller Forces CFX

newcon · April 15, 2015, 10:46

Dear All,
I've looked through these forums and I cannot find a definate answer for my particular set-up:
I've set up my assembly and assigned the propeller to 1000 rpm.
From the monitors I have acquired the mass flow at the outlet (small side) as well as pressures on the propeller's blades in results.
Assembly.jpg

However I am trying to attain the thrust generated on the propeller itself, I have selected in this case the normal force in the fluid in the x axis and achieved a result of -0.93. Is this the value I am looking for? screenshot of the monitor and selection below:
Forces moniter.jpg

Thanks In advance,
Emric

ghorrocks · April 15, 2015, 19:24

You appear to have modelled the impeller and the duct as a solid. Unless you are modelling FSI or thermal fields you do not do this. You only model the fluid domains.

newcon · April 16, 2015, 09:26

Thank you for the reply,

I had added the impeller as an immersed solid as I thought this would apply sorry my screenshots didn't show, there is a fluid domain within the solid shell.
CFX-Pre.jpg

So do you mean I should change the impeller to be a fluid domain?
Or should I set the impeller wall as an interface.
If so how can I assign rpm and find the torque?

Sorry about what I'm sure are such basic questions.

Regards,
Emric

ghorrocks · April 16, 2015, 19:37

Do the rotating machinery examples in the CFX tutorials. There are quite a few. That will show you how to do it.

sohrabmajd · July 1, 2015, 18:13

Hi to all
I modelled a ducted propeller and want to anlysis ansys cfx and defined main domain and propeller as wall in rotating domain but I don't know that how define the duct? When I run solver, it show error.
Help me please?
Tnx

.

ghorrocks · July 4, 2015, 09:32

Showing what you have modelled, the CCL and the error message would help.

sohrabmajd · July 5, 2015, 00:38

Quote:

Originally Posted by ghorrocks

Showing what you have modelled, the CCL and the error message would help.

here is my model file and ccl file.

http://www.2shared.com/file/kygPxAmL/ducted_kaplan.html

the error just show that '' Ansys CFX can't run for your solver"
when i run solver for propeller without Duct it show results.

ghorrocks · July 5, 2015, 07:17

Can you

The error sounds like you have a fundamental setup problem, and possibly your installation of ANSYS. I have no idea what. I would just start the problem simulation again, making sure you do all the steps correctly.

sohrabmajd · July 5, 2015, 10:20

Quote:

Originally Posted by ghorrocks

Can you

The error sounds like you have a fundamental setup problem, and possibly your installation of ANSYS. I have no idea what. I would just start the problem simulation again, making sure you do all the steps correctly.

Did you check my model domains and boundaries?
Are thoses correct? Is The ccl file correct?
I run it again but it show warning thay " return value c0000005>ffff in parse_rv, treating as not run."
"An error has occured in cfx5solve that cd2flow.exe aborted for unknown reasons."
And another error show that " the cfx solver for system fluid flow(cfx) did not produce a result file. Detailed information can be found in the output file for the run."
Mr.ghorrocks
Can you say me that how define my model parts (propeller, duct, ... ) as domains(inlet, outlet, opening, ... ) ?

ghorrocks · July 5, 2015, 19:30

No, I did not check your file. I do not download large files and I do not have time to load up your configuration and debug it for you. I can have a look at your configuration if you post the CCL by itself. My comment was based on the strange error message you reported seeing - I have only seen error messages like that when the CPU type selection for the CFX executable is wrong. This is an installation/computer setup problem.

The error messages you report now are more normal. These error messages are usually generated when the simulation has invalid CCL.

sohrabmajd · July 5, 2015, 19:47

Thanks because of your answers.
It's not large file.(1.19 mb)
The zip file has my ccl file .
When I run a prop. Without duct, it run solver and show me results. But when ducted propeller runs, show errors.
I think that my problem is in define domains with duct.but I don't know that how solve it.

ghorrocks · July 6, 2015, 01:46

You are modelling the solid as a CHT solid (which means heat transfer), yet your fluid is isothermal (which means no heat transfer). This will cause a problem.

There is no need to model the solid as a CHT solid. Just leave it as a cut-out in the mesh.

sohrabmajd · July 6, 2015, 01:55

But how can I change the solid type?
I just modelled it in solidworks and import it into ansys as a frozen.
Is there any way to change solid type?

ghorrocks · July 6, 2015, 07:18

No, you don't change the solid type. You remove it completely. There is no need to model it. In designmodeller or ANSYS mesh just suppress the solid part.

sohrabmajd · July 6, 2015, 08:04

Quote:

Originally Posted by ghorrocks

No, you don't change the solid type. You remove it completely. There is no need to model it. In designmodeller or ANSYS mesh just suppress the solid part.

Oh...I understand.
But I just did suppress body for propeller. I saw it at thread "underwater propeller cfd analysis with ansys cfx" tutorial.swf file that Mr. Alaeddine sent its link for download.
So now, should I suppress propeller and duct together??

ghorrocks · July 6, 2015, 08:13

If you don't care about the temperature field inside the duct then yes, you suppress that too.

April 15, 2015, 10:46	Propeller Forces CFX	#1
newcon New Member Emric E Join Date: Apr 2015 Posts: 2 Rep Power: 0	Dear All, I've looked through these forums and I cannot find a definate answer for my particular set-up: I've set up my assembly and assigned the propeller to 1000 rpm. From the monitors I have acquired the mass flow at the outlet (small side) as well as pressures on the propeller's blades in results. Assembly.jpg However I am trying to attain the thrust generated on the propeller itself, I have selected in this case the normal force in the fluid in the x axis and achieved a result of -0.93. Is this the value I am looking for? screenshot of the monitor and selection below: Forces moniter.jpg Thanks In advance, Emric

July 1, 2015, 18:13	ducted prop. analysis with cfx	#5
sohrabmajd New Member Join Date: Jun 2015 Posts: 29 Rep Power: 11	Hi to all I modelled a ducted propeller and want to anlysis ansys cfx and defined main domain and propeller as wall in rotating domain but I don't know that how define the duct? When I run solver, it show error. Help me please? Tnx.

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April 15, 2015, 19:24		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	You appear to have modelled the impeller and the duct as a solid. Unless you are modelling FSI or thermal fields you do not do this. You only model the fluid domains.

April 16, 2015, 09:26		#3
newcon New Member Emric E Join Date: Apr 2015 Posts: 2 Rep Power: 0	Thank you for the reply, I had added the impeller as an immersed solid as I thought this would apply sorry my screenshots didn't show, there is a fluid domain within the solid shell. CFX-Pre.jpg So do you mean I should change the impeller to be a fluid domain? Or should I set the impeller wall as an interface. If so how can I assign rpm and find the torque? Sorry about what I'm sure are such basic questions. Regards, Emric

April 16, 2015, 19:37		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Do the rotating machinery examples in the CFX tutorials. There are quite a few. That will show you how to do it.

July 4, 2015, 09:32		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Showing what you have modelled, the CCL and the error message would help.

July 5, 2015, 07:17		#8
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Can you The error sounds like you have a fundamental setup problem, and possibly your installation of ANSYS. I have no idea what. I would just start the problem simulation again, making sure you do all the steps correctly.

July 5, 2015, 19:30		#10
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	No, I did not check your file. I do not download large files and I do not have time to load up your configuration and debug it for you. I can have a look at your configuration if you post the CCL by itself. My comment was based on the strange error message you reported seeing - I have only seen error messages like that when the CPU type selection for the CFX executable is wrong. This is an installation/computer setup problem. The error messages you report now are more normal. These error messages are usually generated when the simulation has invalid CCL.

July 5, 2015, 19:47		#11
sohrabmajd New Member Join Date: Jun 2015 Posts: 29 Rep Power: 11	Thanks because of your answers. It's not large file.(1.19 mb) The zip file has my ccl file . When I run a prop. Without duct, it run solver and show me results. But when ducted propeller runs, show errors. I think that my problem is in define domains with duct.but I don't know that how solve it.

July 6, 2015, 01:46		#12
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	You are modelling the solid as a CHT solid (which means heat transfer), yet your fluid is isothermal (which means no heat transfer). This will cause a problem. There is no need to model the solid as a CHT solid. Just leave it as a cut-out in the mesh.

July 6, 2015, 01:55		#13
sohrabmajd New Member Join Date: Jun 2015 Posts: 29 Rep Power: 11	But how can I change the solid type? I just modelled it in solidworks and import it into ansys as a frozen. Is there any way to change solid type?

July 6, 2015, 07:18		#14
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	No, you don't change the solid type. You remove it completely. There is no need to model it. In designmodeller or ANSYS mesh just suppress the solid part.

July 6, 2015, 08:13		#16
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	If you don't care about the temperature field inside the duct then yes, you suppress that too.