Optimization of a Lobed Perforated Panel Diffuser - A Numerical Study of Orifice Arrangement

Heating Ventilating and Air Conditioning (HVAC) systems are primarily designed for ensuring good indoor air quality and thermal comfort. However, building energy requirements tend to put demand on reducing air change rates. Passive control of jet flows in order to enhance mixing and entrainment may be a solution to this problem. Our purpose is to develop new air diffusers, in order to ameliorate the users’ thermal comfort and air quality. When the diffuser is a lobed perforated panel (Meslem et al, 2010), the optimization of jet entrainment consists of optimizing the spacing between neighboring orifices and their relative arrangement on the panel. The objective is to conceive a perforated panel diffuser with high entrainment and high perforation rate. In a recent study (Meslem et al, 2011) the flow field of a turbulent twin cross-shaped jet was investigated experimentally and numerically using different turbulence models. In comparison to Particle Image Velocimetry (PIV) measurements, it was shown that among the investigated turbulence models, the SST k-w model is capable of reproducing reasonably well jet interaction, global expansion and ambient air entrainment when the flow is numerically resolved through the lobed diffuser. Based on the previous experimental validation of the SST k-w turbulence model, in this work, numerical simulations of parallel cross-shaped jets in different flow configurations are analysed using this model. This study deals with the effect of orifice arrangement and spacing on jet entrainment. The parametric study put into evidence an optimal configuration which will be transferred to the scale of a real air diffuser.