Lobed jets for improving air diffusion performance in buildings

A new innovative design concept for the indoorair conditioning systems is proposed. Thisconcept uses passive control and modularly airdiffusion devices and aims complying with boththernial conifort and energy efficiencyobjectives. Passive control aspect is studiedthrough the comparison between a circularreference jet and a lobed jet having the sameexit area and initial flow rate. It is shown that across-shaped lobed orifice allows a consequentincrease of the entrainment within a large rageof initial Reynolds numbers. Moreover the jet'sthrow is conserved despite its strong initialinduction. Streamwise volumetric flow rates andcentreline velocities evolutions display anatypical region, in the range of the lowReynolds numbers, where comnionly usedprediction laws are not anymore valid.Lobed jet's entrainment efficiency is elucidatedthrough the analysis of the initial vorticalstructures dynamics.