Influence of Induction Box Ports on Near Flow Field Mixing

This paper presents the influence of air blown through an injection nozzle in a circular section induction box on the axial jet and air induction. The effect of the turbulent jet on the axial mean streamwise velocity decay, turbulence characteristics, mass entrainment and temperature distribution in the near flow field of an enclosed numerical space is investigated. Convergence of the steady state simulations is achieved by using the RNG kappa-epsilon turbulence model. Comparisons of the axial mean streamwise velocity decay, turbulence characteristics and the temperature distribution in an enclosed space are reported for an injection nozzle, and another similar simulation was conducted for a circular section induction diffuser box with open ports at specific positions to evaluate its performance. The numerical analysis was validated by prototype experiments using a similar injection nozzle in a test room 11 m in length, 5.5 m wide and 2.5 m high. Measurements of the streamwise velocity and temperature distribution were made inside the room on a grid with the help of a hotwire anemometer and digital thermometer, respectively. From the analysis of the data, it was found that the near flow field streamwise velocity, turbulence kinetic energy and air entrainment characteristics of the flow were significantly influenced by the air induction diffuser ports.