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Show v : kinematic viscosity ~ dimension of the mesh following the normal to the wall Radiative fluxes - The net radiative fluxes are calculated as part of DE MARCO and LOCKWOOD's model. For a wall normal to the x axis (20) 3k ox THE COMPUTER PROGRAM - The computer program was written in FORTRAN. It reads in a file the input data which includes that of the space meshing. It restitutes, as the calculation is being performed, at adjustable frequency, the fields of temperature, pressure and velocity and the heat fluxes at the outside walls. Using these discrete values it is possible to plot the isotherms, isobars and velocity vectors in each volume. NUMERICAL APPLICATION OBJECTIVES - The immersion tube is intended to replace the radiant roofs mounted above galvanization baths. Equipment of this type records losses through the combustion products of around 50%. Given the technicoeconomic context of intense competition between the different energy forms in France, GAZ DE FRANCE sought to develop an immersion tube operating at 65kW (ncv) with maximum losses through the combustion products of 20%. The desired optimum was to produce a heat transfer in the bath of 70kW/m2 and a temperature which was acceptable for the material used to make the internal recirculating tube (type AISI 310 refractory stainless steel). The association between a high velocity burner and a recirculating tube is already used in a radiant tube developed by GAZ DE FRANCE for controlled atmosphere heat treatment furnaces. However, the geometric conditions and the temperature and flux levels are different. A new design was therefore required. The program described in the previous paragraph was thus applied to this equipment. Only the part situated beyond the self-recuperative burner was modelized, as indicated in figure 2. A version adapted to the presence of a solid wall within the physical domain under study (the recirculation tube) was produced. The conduction across this wall in steady flow conditions was taken into account. The symmetry chosen was axisymmetric, which corresponded exactly to the Physical domain modelized Axis of symmetry Recirculating tube BURNER IV 1000 Fig. 2 - Geometry of single-ended immersion tube 130 |