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Show - 6- 4.1.4 Test measurements and main results Following burner characterization (see section 2) and taking into account the temperature constraints imposed by the probes used, we performed detailed flame analyses for the four operating points below : *version without staging, * version without staging, * version without staging, * version with staging, 200 kW, air at 25°C, 200 kW, air at 400°C, 100 kW, air at 400°C, 200 kW, air at 400°C. For each of the four operating cases above, an excess air of 10% and a furnace temperature of 1 ,280°C were applied. For each measurement technique, the mesh comprises approximately 150 points. The meshed zone extends longitudinally from z = 180 mm to z = 1,030 mm and laterally from x = 450 mm to x = 100 mm along the plane y = 0 mm. Geometric constraints prevented us from getting any closer to the quarl outlet. Figures 5, 6 and 7 show the mean temperature, axial velocity and CO concentration fields for the four operating cases studied. In the same way as with tests performed on a cold model, the different fields show good symmetry. The impact of preheated air, power and staged combustion air is clearly brought out : - preheating air creates a shorter flame and a higher mean local temperature at the quarl outlet ; - reduced power creates a smaller flame but the maximum value of the mean local temperature is close to the figure obtained at rated power ; - air staged combustion modifies the flow and creates a longer flame that is narrower close to the quarl and broader at a distance. The CO values recorded at the quarl outlet are low, regardless of operating conditions. Most of the combustion takes place inside the quarl or immediately downstream. A detailed analysis of all measurements gives us a better grasp of the mechanisms of NOx formation and notably shows the role played by the operating parameters of the 8SI-1 burner. 4.2 Numerical simulation 4.2.1 Introduction The simulation of non-reactive flows on the 8SI-1 burner described in section 3.2 served as a basis for the simulation of reactive flows. In the same way, meshing was performed in 20 or 30 according to whether combustion air was staged or not. ... 1 .. |