Abstract
In order to elucidate the heat and flow characteristics of multiple impinging jet (MIJ), we conduct the DNS (direct numerical simulation) of four round impinging jet arranged at an inflow of flow field. To realize the high accurate computation, the discretization in space is performed with hybrid scheme in which sine or cosine series and 6th order compact scheme are used. For the surrounding boundary condition, in order to reduce the artificial noise due to the occurrence of vortex at the outflow boundary, a fringe technique is newly developed and introduced at the surroundings of computational volume. As a control parameters, a separation between each jet, i.e., jet-to-jet spacing is varied. From view of instantaneous and time-averaged flow field, it reveals that the generation of vortical structures are enhanced due to interactions between each jet, and that a large-scale upward flow, generally called as fountain is formed between each jet according to the jet-to-jet spacing. In addition it turns out that the both flow and heat transfer characteristic of each jet comes close to that of single impinging jet (SIJ) beyond a specified jet-to-jet spacing. Further the heat transfer performance in the interaction region between jets is evaluated compared to that of SIJ and the contribution of recirculation flow to the heat transfer is clarified.
