An Experimental Study on Turbulent Circular Wall Jets

The results of a laboratory investigation on the characteristics of a circular three-dimensional turbulent wall jet are presented. Measurements were performed up to 50 nozzle diameters using a combined Particle Image Velocimetry and Planar Laser Induced Fluorescence approach that captured simultaneously the planar velocity and concentration fields. Both the velocity and concentration profiles exhibited similarity in the streamwise and spanwise directions after sufficient distance from the nozzle. The existence of a secondary mean motion is shown to be responsible for the far greater lateral spread compared to the normal spread for both the momentum and scalar mixing. Using curve fitting, the mean properties of the three-dimensional wall jet are approximated. The consistency of the relationships is further examined based on mass conservation and momentum balance.