(129b) A Comparison Study of Turbulence Statistics In the Mixing Regions of a Confined Jet and Wake

Kong, B. - Presenter, Iowa State University
Fox, R. - Presenter, Iowa State University
Hill, J. - Presenter, Iowa State University

Experimental data from combined particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) measurements were used to analyze the flow between the two scalar interfaces of a confined turbulent jet and a turbulent wake flow. The fluid of the center stream in both flow cases contains a fluorescent dye, and normalized PLIF images were used to identify the inner and outer boundaries of the center stream for both flow cases. The growth of the boundaries in both flow cases were determined and analyzed. The mean and fluctuations of the passive scalar concentration, velocity, stain rate, and vorticity were determined relative to the locations of the two boundaries. Both the jet and the wake case showed sharp jumps at the boundaries in the mean passive scalar profiles, and the curvatures between the two boundaries indicate that the values in the mixing region are closer to the mean passive scalar values in the stream with high momentum. The mean streamwise velocity profiles show no sharp jumps at the boundaries in both cases, and the velocity values continue to change beyond the boundaries. In the jet case, the fluctuations of the passive scalar show high values close to the outer boundary of the jet, and the streamwise velocity fluctuations show high values near the inner boundaries of the jet, as do stain rate and vorticity. The results of the wake case are very symmetrical about the center of the wake, indicating the presence of the vortex street.