Calculation of a cooling

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ThomasK96 posted this 27 February 2018

Hello everybody,

 

I'm pretty new to using Ansys AIM and need a little help.

I would like to calculate a cooling, for that I used Fluid-Solid Heat Transfer.

I came across the problem that I do not know how to enter the temperature in the roller bearing (see figure no. 2) correctly. With the "Temperature" command, the cooling (see Figure # 1) has no effect on the temperature, but I only have information about the bearing that it heats up to 55 ° C.

 

Can you help me?

 

Many Thanks

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peteroznewman posted this 27 February 2018

Hello Thomas,

The one attached image is not enough to help. 

What version of AIM are you running?

Please do File, Archive and save a .wbpz file that you can attach to your post.

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ThomasK96 posted this 28 February 2018

Hello,

thanks for your quick reply. I running the version "ANSYS AIM ACADEMIC STUDENT Release 18.2".

I assumed a heat flow in the example attached. I can not substantiate this value. I accepted the value to get a result in the structural burden.

Thank you

Attached Files

peteroznewman posted this 28 February 2018

 This model looks like a 15 degree slice out of a 360 degree model.  That means on the cut faces, there should be a Periodic Rotational boundary condition.

 

    

I have to study this some more and will post again later.

peteroznewman posted this 28 February 2018

Thomas, if you want to download and install ANSYS Student 18.2 to have as well as AIM Student 18.2, you will be able to open the attached archive. I made a 2D axisymmetric model of your geometry. It has a Steady State Thermal model to calculate temperature, and a Static Structural model to calculate thermal expansion.

I just made up numbers for the Film coefficient for the surfaces in contact with water or air at 25 C and applied a temperature of 55 C to the bearings.

There is bonded contact between all the parts, so I don't know if that is a correct assumption, and if some parts can slide, then the stress result below would not be correct.  Since all the materials are steel, there is not much stress due to thermal expansion, however, I left the base of this assembly free to expand in the X direction, which may not be a correct assumption either.

Let me know if you have questions.

Regards,

Peter

 

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ThomasK96 posted this 01 March 2018

Hi Peter,

thank you for your effort. I'm about to download Ansys 18.2 Student to follow your steps. Your assumption with the 15° Model is correct, your hint is very helpful.

In your Steady-State Thermal model, the rolling elements and the outer ring have a temperature of 55 ° C. I was hoping that I can see through the calculations, what influence the cooling line has on the rolling bearing. I have a second model, which has only two instead of three cooling pipe. For this I would like to make a comparison.

Is there a way to see how much the cooling line cools the bearing? In reality, a thermometer sits on the outer ring. The value at this point is important for me. In your calculation this is 55 ° C.

 

Kind regards,

Thomas

 

peteroznewman posted this 01 March 2018

Hi Thomas,

I had two models, the one above where the temperature is set to 55° C and the one attached to this post where the bearing is assigned an Internal Heat Generation value.

You should use the second model to study the effect of two versus three cooling lines. The model that sets 55° C on the bearing will put more heat into the bearing to achieve that temperature with three cooling lines and less heat with two cooling lines.  The model that has a fixed Internal Heat Generation will show how the temperature can be reduced by using three cooling lines instead of two. Below is an illustrative example. Note: I made up film coefficients and internal heat generation for this illustration. You should adjust them to match your data. In the top figure, the temperature on the inner ring is 55.3 C while the bearing is 52.8 C.  In the bottom figure, one cooling line has been removed and the bearing temperature increases to 58 C and the inner ring temperature increases to 60.8 C.

Regards,

Peter

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ThomasK96 posted this 01 March 2018

Hi Peter,

Unfortunately I could not see the attached file yet. I'm currently at work and do not have the right to download programs here. I will look at the file when I am at home.

Thank you for your help.

Regards,

Thomas

peteroznewman posted this 01 March 2018

Hi Thomas,

I was perfecting my post and improving the model. Please reread the above post and download the attachment when you can. Let me know if you have questions.

Regards,

Peter

ThomasK96 posted this 01 March 2018

Hello Peter,

thanks for the model, it helped a lot. I just have no questions. I'll get in touch when new questions arise.

Thank you

Thomas

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