Joint laser-Doppler/laser-induced fluorescence measurements in a turbulent jet

The development, set-up, and test of an optical system are described for combined laser-Doppler and laser-induced fluorescence measurements along with the verification of its performance in a liquid flow. The range of applicability is given, and it is shown to depend on a number of effects, such as incident dye concentration, photochemical decomposition of the organic dye as a function of laser light intensity, and parameters describing the geometry of the optical set-up. Distortions of the Gaussian light beam profile are shown to exist if the light intensity of the incident laser radiation is not matched to the dye concentration. Verification experiments in turbulent jet flow show the information contents of measured data, e.g., probability density distributions of velocities and concentration as well as correlations at various locations in a turbulent round jet.