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Show 0 50 100 150 200 250 300 Distance from Air Inlet [mm] Figure 5 Profiles of temperature uniformity along furnace height : Upa u»a*r> P i * * * fill t :Ugfc «ww)u i Figure 6 Visible light intensity profile [1] (a) L o w temperature / normal oxygen (b) High temperature / low oxygen To validate our simulations, some experimental results provided by Hasegawa et al. [1] are also given here in Fig 6 and Fig 7. From both the measured visible light intensity and the calculated temperature distribution, the flame shape can be clearly observed, and the consistence of the flame shape appears between the experiments and the simulations. Comparing the flame temperature, it is found that the calculated temperature is higher than the measured one. As mentioned above, a zero heat flux thermal boundary condition was assumed on the furnace walls because of lack of experimental data, which resulted in the over predicted flame ::f:f»| temperature. «K* *ot iso tee 520 t<» *;* 225 40 &0 SO iK> (10 i#i ni w/ mm NOx emission. The N Ox emission in the gas combustion mainly depends on the flame temperature. The high level flame temperature in the highly preheated air combustion must W?M§ Jmt.JL.L M i l l resu^ m tne m £ h N O x emission, M m m which has also been verified in Figure 7 Measured temperature distributions [1] (a) L o w temperature / normal oxygen (b) High temperature / low oxygen our simulations. Figure 8 shows the NOx concentration distributions in the central |