In this study, the effects of having a pulsative inflow to a wall jet within a 2-D enclosure are investigated using both (Particle Image Velocimetry (PIV) measurements and Computational Fluid Dynamics (CFD) simulations. The main hypothesis of the study is that the pulsation can improve the mixing performance of the wall jet into the small-scale 2-Droom model. Both CFD and PIV experiments focused on comparison of downstream flow-field of a wall-jet with constant and pulsative inflow modes.
Obtained results have proved that the pulsation has the ability to improve mixing thorough generating secondary vortices in the downstream of the wall-jet, and same global airflow pattern exists for both of the cases but with generation of more eddies and local periodical velocity variations for pulsation mode. This periodic generation of turbulence with pulsative inflo9w has happened despite the relatively low Reynolds numbers. The bigger size of boundary layer and higher turbulent kinetic energy for the pulsative inflow in comparison with the same flow rate in constant flow mode could result in more ventilation effectiveness without the need to increase flow rate. When itcomes to real-scale ventilation applications, a lower pulsated inflow could produce the same acceptable results in terms of mixing efficiency as a higher constant flow rate, which results in a more energy-efficient ventilation strategy with lower risk of draught and thus better thermal comfort. The computational is done thorough grid independency study.
The study is therefore done with 3D SST-kΩ which yielded good prediction of velocity profiles near walls. For predicting turbulence parameters in the center of the domain SAS has been used which has been successful to get close toreality results.