Abstract
The general context of the present study is the design of high induction HVAC air diffusers by means of passive jet control. When the diffuser is a perforated panel with lobed orifices (Meslem et al. 2010), the optimization of jet induction consists in improving the orifice's geometry, the spacing between orifices and their arrangement on the panel. In this study, the flow field of a turbulent twin cross-shaped jet is investigated numerically using the standard k-epsilon model, the Shear Stress Transport (SST) k-omega model and the Reynolds Stress Model (RSM). The results are compared with PIV measurements. The objective is to assess their capability and limitations to predict the significant features of twin jet flow when the flow is numerically resolved through a lobed diffuser. It is shown that the k-epsilon and RSM models are more appropriate for predicting potential jet core length, the change in jet centreline streamwise velocity, and flow expansion in the symmetry plane of the twin jet flow. However, these models overestimate the overall flow expansion and the jet volumetric flow rate. The SST k-omega model seems more appropriate for the prediction of such dynamic integral quantities. A high level of turbulent kinetic energy predicted by the k-epsilon and RSM models in the near field of jets is probably the reason for this overestimation of jet induction. The SST k-omega model would appear to be the most appropriate tool for optimizing orifice design, orifice to orifice spacing and relative orifice orientation on a perforated panel diffuser. (C) 2011 Elsevier Ltd. All rights reserved.