topic Re: Torque calculated by different ways shows zero value in CFD Forum

Torque calculated by different ways shows zero value

Atheel.Jameel — Thu, 24 May 2018 13:54:59 GMT

Hi All,

I started to face a physical problem in CFD modelling with inventor 2018.2, and appreciate any help from you.

Regarding the torque calculation, I wanted to ask you about my problem. I am running a simulation for an impeller to drive air (suck it) and discharge it through air ventilation unit. I use rotating region material type with RPM. the problem is i don't get the torque calculated and it gives me values zero when I try to calculate it using wall calculator or reviewing the rotating region results or even by using the API tool using Add-Ins. Any help would be appreciated please...

Many Regards,

Re: Torque calculated by different ways shows zero value

Jon.Wilde — Thu, 24 May 2018 14:02:13 GMT

Hi,

Thanks for creating a new thread for this, much appreciated 🙂

To start from the beginning, have you seen this article and did you follow it? Rotating Regions

Reading it now, it looks like a lot of text, although I would say that every point is important.

If you are confident that you have it set up properly, feel free to share a CFZ (support file) and we can take a look.

Just an FYI - the pump API is not doing anything that you cannot do manually, let's get the basics working first.

Thanks,

Jon

Re: Torque calculated by different ways shows zero value

Atheel.Jameel — Thu, 24 May 2018 14:21:28 GMT

Hi Jon
Thanks for your help. Unfortunately I cant share the CFZ file as the design is not mine. however I am not completely depending on API as I used other ways to present the torque and still shows zero value. I went through the Rotating Regions long time ago and following it thoroughly. The only thing is I am not using high adequate mesh (I know that) because I just want to get some preliminary results to start from which I not consider it a reason for not calculating the torque in my case.
Any help please or idea would be appreciated..
Regards,
Atheel,

Re: Torque calculated by different ways shows zero value

Jon.Wilde — Thu, 24 May 2018 16:40:23 GMT

Hi Atheel,

A small suggestion - unless a post provides you with a solution, don't mark it as solved. We might not check in on it again 😉

From looking in our database, although your account is not connected, I am pretty sure you have a subscription with us, is that correct?

How about we have your contract manager set your account up properly and we can move this to a 1:1 case for you to share the CFZ with us privately?

Otherwise it is pretty impossible to help.

Thanks!

Jon

Re: Torque calculated by different ways shows zero value

Atheel.Jameel — Fri, 25 May 2018 08:01:33 GMT

Dear Jon,

Thanks for trying to help me. Actually you are totally right. I need to post the file with the results and I am working on that right now. Just one question... I did not do such a thing before, but how I can attach and post it here?

Regards,

Atheel,

Re: Torque calculated by different ways shows zero value

Jon.Wilde — Fri, 25 May 2018 08:34:29 GMT

When you reply, scroll down a little and you will see the attach option 😉

If it fails, this is because it is too large (a support file should be OK though). If this happens, maybe use Dropbox/WeTransfer etc...

If you can get me (or others!) the file today we can take a look. I should have time for you I think, so get uploading 😄

Re: Torque calculated by different ways shows zero value

Atheel.Jameel — Fri, 25 May 2018 13:20:07 GMT

Dear Jon,

Please find attached my CFD file and the Excel sheet. I tried to run the problem with a flow rate in GPM near to what I expect to get in m3/s. The expected flow rate in my problem is 2.41 m3/s. when I ran it before starting from random flow rate, I got results, but not this time with the expected one.... no sure whats going wrong... Any help or thoughts?

Re: Torque calculated by different ways shows zero value

Jon.Wilde — Fri, 25 May 2018 15:44:34 GMT

Hi,

Please could you share the CFZ file? We can't do anything with just the cfdst.

The CFZ is like a zip that contains the cfdst and all the others we need 🙂

Thank you!

Re: Torque calculated by different ways shows zero value

Atheel.Jameel — Tue, 29 May 2018 09:14:32 GMT

Hi Jon,
Sorry for the late response. Please find attached the CFZ support file for my case and the Excel file showing the performance curve. As you can see, no torque values. Could you please give me any hint?
Regards,
Atheel,

Re: Torque calculated by different ways shows zero value

Atheel.Jameel — Tue, 29 May 2018 09:20:21 GMT

Hi Jon,
I could not upload the CFZ as it is, therefore, please find attached the CFZ support (compressed rar) file for my case.
Atheel,

Re: Torque calculated by different ways shows zero value

Jon.Wilde — Thu, 07 Jun 2018 11:20:18 GMT

OK, thanks for sharing. I see it and I see the issue.

You have a coarse mesh and no rotating region.

Please refer to the article I attached in my first post and watch the hangout session that is linked at the bottom of it 🙂

Let me know how you get on!

Thanks,

Jon

Re: Torque calculated by different ways shows zero value

Jon.Wilde — Thu, 21 Jun 2018 07:34:51 GMT

Hi,

How did this work out in the end, all solved?

Thanks,

Jon

Re: Torque calculated by different ways shows zero value

Atheel.Jameel — Thu, 21 Jun 2018 08:05:11 GMT

hi Jon,

I am still running on a high resolution mesh for multiple points, my PC is not any good for 2018 version. I will inform you once I get final results.

Regards,

Atheel,

Re: Torque calculated by different ways shows zero value

Atheel.Jameel — Wed, 27 Jun 2018 09:15:59 GMT

Hi Jon,

Thanks a lot, high mesh definitely helps as it working now with adding RR. Just one more question regarding the RR in Axial fan application, I am trying to design an new Axial fan just by using RPM value with out giving any flow rate. I had a success using Autodesk CFD to model couple of designs with out building RR and just making the solid fan rotates with specific RPM, however I am still not sure about the flow rate outcome values. The reason not using RR cause I think RR would affect on the velocity profile and/or its trend when the air touching the blades naturally in case of no RR... Correct me please if I am wrong...

Regards,

Atheel,

Re: Torque calculated by different ways shows zero value

Jon.Wilde — Wed, 27 Jun 2018 11:10:58 GMT

I would just stick to using the RR, this is exactly what it was designed for 😉

You might also like to test P=0 at the inlet and either a P=0 at the outlet or some with a flow rate at the outlet (let CFD predict the pressure for you).

This way you can build up a performance curve.

Re: Torque calculated by different ways shows zero value

Atheel.Jameel — Wed, 27 Jun 2018 11:31:58 GMT

Hi Jon,

Actually, yes I am using P inlet and P outlet=0. No Flow rate as I want to predict it based on the RPM. But, regarding how the air reacting with the geometrical shape of any Fan or Impeller... is it correct and not artificial due to using the RR in this setup?

I know it gives me the needed flow rate when I test an existed design with known flow rate data. But, does it show or present the real aerodynamic configuration or air trend when we use RR?

If not!!! what is the solution then?

Why we don't get the flow rated naturally build up (with no RR) by making the just the Axial fan running with RPM and zero pressure Inlet Outlet? so we wont get any artificial aerodynamic configuration pre and after the Fan. Any other BC set up known to do so if this make sense?

Regards,

Atheel,