OCR Text |
Show Analysis of System An analysis of FM control relative to AM control is initially performed by investigating the effects each control technique has on furnace enclosure recirculation rate. The hypothesis is that the control techniques which results in the greater rate of recirculation would also produce the greater convective heat transfer coefficient. The problem is therefore reduced to the selection of a suitable model or models which describe the hydrodynamic phenomena. The accepted practice in direct fired batch type heating processes is to locate burners on the sides of the furnace with their axis normal to the wall with center to center spacing being of the order of 2 feet. In this case, the flow is assumed to be similar to the axis symmetric circular jet as described in Schlichting"- *•*. The differential equations governing the flow, which is assumed turbulent, are identical to those for a laminar jet with the exception that the virtual kinematic viscosity replaces the kinimatic viscosity e , i.e., o du + v 3u = 1 _8_| 3u\ 9x 3y o y 9y I 3y / and 3x dy = 0 The boundary conditions are: v (x,y) = 0, 9u (x,y) = 0 and u(x,y) y = 0 8y »y = 0 7-6 |