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-   -   heat conduction in solid - mismatch to exp. res. (http://www.cfd-online.com/Forums/fluent/49984-heat-conduction-solid-mismatch-exp-res.html)

Ralf Schmidt December 5, 2008 12:56

heat conduction in solid - mismatch to exp. res.
 
Hello,

I simulate inst. cooling of a steel cylinder with fluent, but my results are far from matching with experimental data.

The situation is as follows:

- 2D simulation, axis symmetry

- 100 mm steel cylinder (diameter is 20 mm) starting temp. is ab 1023 K

- cooling from the front face with an impinging jet, almost 1D cooling, comparable with the Jominy end quench test, see http://info.lu.farmingdale.edu/depts...ominytest.html

- instead of water it is high pressure GAS => HTC is between 1500 and 2500 W/m2 K (that matches with data from literature)

- steel cylinder material data: -- heat conductivity temp. dependent, between 18 and 28 W /m K -- density 7900 kg/m3 -- heat capacity temp. dependent, between 450 and 630 J/ Kg K -- austenitic steel

Now, we are interested in the cooling rates at different distances from the frond face, as well as the cooling time from e.g. 800C to 500C (it is called "t800-500")

The simulation fits very well the measured data up to a frond face distance of ab 20 mm. BUT, the t800-500 data we simulate for higher frond face distance are more than twice as high as the experimental values!! (so the cooling is slower).

I have no idea, whats wrong. I tried a lot of different possibilities... like increasing the impinging jet turbulence, decreased the impinging jet temperature, changed the material parameters to maximum conductivity,....

Nothing helps. So there is maybe a principle problem with fluent???

Any Idea?

Ralf


mange December 9, 2008 09:34

Re: heat conduction in solid - mismatch to exp. re
 
What are your BC? can you be sure that energy is transported out of the domain in a satisfying way?


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