NUMERICAL ANALYSIS OF MULTIPLE JETS IMPINGING ON A MOVING SURFACE

Multiple jet impingement is an effective heat transfer process that enables uniformization of the cooling process. In addition to flow and geometry variables, the motion of the target plate is paramount to several applications, such as reflow soldering process, food processing, drying, and heat treatments, which increases the complexity of the flow over the surface. This work analyses numerically the effect of the target plate motion in multiple jet impingement performance and compares the results with a static plate case. To conduct this research, a widespread commercial software, the ANSYS FLUENT, is used. Between the different turbulence models available to conduct the numerical simulations, the SST k-omega model is implemented since it provides accurate predictions of impinging flows at reduced computational costs. From the numerical modeling, a detailed characterization of the flow is performed, and the heat transfer is analyzed at the vicinity of the target plate. Since a low nozzle-to-plate distance (H/D=2) and jet-to-jet spacing (S/D=3) are implemented, strong interactions between jets are identified. These interactions are well predicted in both static and moving plates. Jet's shear layer interactions are observed prior to the impingement as well as wall jets collisions over the surface. Moreover, the increased turbulence intensity of the flow, induced by the plate motion, is accurately predicted by the numerical model. Strong shear layers, generated in direction to the motion, are observed, which leads to a modification of the boundary layer compared with the static plate. This effect increases the local heat transfer rate over the moving plate as well as the complexity of the flow compared with the static plate.