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Old   April 28, 2008, 02:35
Default A problem with combustion
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Hi all - i have problem with following situation (I use CFX) but suspect that this is not only about the code but with physics itself. I simulate non-premixed combustion in domain of sizes 3x3x12 m. The heated up air (1200C 5 m/s) and fuel (propane 20C 50 m/s) are injected through two inlets on the one side of 3 x 3 m wall. After that they create the flame sheet and follows along the long line of the arrangement. They forms the U-shape flow and are directed back to outlet which is in opposite side of the frontal 3 x 3 wall. My problem is, that despite the temperature in the flame seems to be right ~2100K in the closure to inlets, as the flame goes along the line the gases has temperature of only 20K and forces the flame up (there is buyonancy). The walls of the domain are set to 1400C and emissivity is 0.85. This is very strange - how the temperature drops in this matter? Can anyone help? The opening is in the outlet BC. The residuals and imbalances are both ok.
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Old   April 28, 2008, 09:55
Default Re: A problem with combustion
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Sorry - the temperature decreases to 20C not 20K. Anyway this is strange. I was trying to simplyfy this situation and cut a domain into a half - along long line as the flame goes straign to outlet. I noticed that approximately 2 m before outlet plane the temperature also decreases quite rapidely to 400K. I dont know why.

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