Time-Averaged Mixing Behavior of Circular Jet in Counterflow: Velocity and Concentration Measurements

The time-averaged mixing behavior of a circular jet issuing into a counterflow is investigated in the laboratory at a number of jet-to-current velocity ratios between 3 and 15. The velocity field is obtained from laser Doppler anemometry measurements and the mean concentration field of the jet is measured by laser-induced fluorescence. A similarity analysis is performed on the radial profiles of mean velocity at successive streamwise stations. This is achieved by expressing the mean velocities as jet excess velocities over the ambient counterflow. The agreement of data to the similarity profiles suggested by previous studies is discussed. A similarity analysis is also attempted for the radial distributions of mean concentration. Data are presented on the axial growth of the momentum width and the concentration width of the jet in a counterflow.