VELOCITY AND CONCENTRATION FLUCTUATIONS OF TURBULENT BUOYANT ROUND JETS

This experimental study aims at investigating the influence of the buoyancy upon the turbulent diffusion of gas jets. Carbon dioxide, helium and air are separately discharged upward or downward from a perpendicular convergent round nozzle into still air. The velocity and the concentration measurements are carried out in order to investigate the diffusion structure of the buoyant jet. The influence of the exit Froude number on the nondimensional length from the nozzle exit to the end of the fully developed region is examined. The velocity and the concentration fluctuations are analyzed in detail for understanding the local character of the jet diffusion. The probability density functions of the velocity and the concentration fluctuations are determined over the whole region of the jet. The skewness and the flatness factors of these probability density functions are also calculated.