Flow dynamics of a plane jet impinging on a slotted plate: Large eddy simulation

A turbulent plane jet impinging on a slotted surface is simulated using Large Eddy Simulation LES. The Reynolds number, based on the jet-exit velocity and width, is equal to 5435. The slotted surface is placed at a distance equal to four times the jet-exit width. Three computational grids were used to assess the accuracy of the LES simulations conducted. The interaction effects of the jet with the slot propagate away from the slot region and manifest into pressure perturbations. Interesting phenomena were observed when linking the dynamic flow features upstream and downstream of the slotted surface. LES predicted three dominant frequencies at different points from time signals of velocities and pressure. The dominant frequency of the pressure field, away from the slot, corresponds to that of coherent vortices which follow a trajectory that is far from being deviated towards the wall jet or into the slot of the impingement wall completely. Among these turbulent structures of interest, pairs of opposite, but in phase, vortices are responsible for promoting the occurrence of the throttling phenomenon. The characteristic frequencies of the pressure field are similar upstream and downstream of the impingement wall. The peaks of the fluctuating pressures, away from the slot, correlate well with the minimum flow rate through the slot which correspond to the throttling phenomenon.