Effects of Nozzle Geometry on Air Flow Jet and Temperature Distribution in an Enclosed Space

The aim of the work was to investigate the effect of upstream geometry of the nozzle on the turbulence mixing and temperature distribution in still air large enclosed spaces. Prototype experiments were carried out with the JETs (Jet Environmental Techniques) existing nozzle geometry in a test room. These were used to validate, under steady state conditions, the application of an RNG kappa-epsilon turbulence model. In the next stage a range of nozzle profiles of similar inlet and contraction diameters were tested under identical conditions similar to the prototype test room. Comparisons of the axial mean streamwise velocity decay, mass entrainment, turbulence characteristics and the temperature distribution in the enclosed space were reported for each of the nozzle geometries to evaluate their performance in the space. From the analysis of data, it was found that enhanced mixing between the jet flows and surrounding fluid was noticed for the nozzles which generated relatively higher turbulence kinetic energy in the near field transition region. Examination of the temperature profiles in the numerical space revealed that nozzles generating high turbulence kinetic promoted better mixing of the temperature in the near flow field and the jet fluid.