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Show ~irst, the effect of gas and oxygen velocity on total radiative flux was tested. -- he experiments selected flames B, E and l! maintaining the peD of oxygen nozzles at 200 mm. Figure 12 shows the effect of gas and oxygen velocity on the total radiative flux. A lower gas and oxygen velocity resulted in a higher total radiative flux. Figure 13 shows the effect of peD of oxygen nozzles. The experiments selected flames D, E and F, while maintaining the velocity of gas and oxygen constant at 48 and 58 mls respectively. The peD of oxygen nozzles was varied from 100 to 300 mm. Smaller peD of oxygen nozzles, that is, a narrower gap between the two oxygen nozzles, resulted in higher total radiative flux. The total radiative flux from the FDI flames was generally low compared with that from the co-axial conventional burners previously tested. Since it maximizes the self-induced EGR effect, the FDI combustion appeared to create a rather flat distribution of total radiative flux. Figure 14 shows the effect of gas and oxygen velocity and the peD on NOx emission. Higher gas and oxygen velocity or wider peD of oxygen nozzles resulted in lower NOx emission. The effect of gas and oxygen velocity became marginal with the peD wider than 200 mm. EFFECT OF MOMENTUM ON HEAT FLUX AND NOx Figure 15 shows the effect of total momentum of gas and oxygen at the burner on the mean total radiative flux. The total momentum is the summation of momenta of fuel gas and oxygen through the burner as shown in Tables 1 and 2. The mean total radiative flux is the average of six radiative heat fluxes measured. Figure 14 includes all the results in this study. Lower momentum or lower velocity generally resulted in higher radiative heat flux. The total momentum appears to control the radiative heat flux. Figure 16 shows the effect of total momentum of gas and oxygen at the |