Temperature measurements of micro-droplets using pulsed 2-color laser-induced fluorescence with MDR-enhanced energy transfer

• Published in: Experiments in fluids Vol. 57; no. 12; pp. 1 - 14
• Main Authors: Palmer, Johannes, Reddemann, Manuel A., Kirsch, Valeri, Kneer, Reinhold
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-12-2016; Springer Nature B.V
• Subjects: Color; Droplets; Dyes; Emission analysis; Energy transfer; Engineering; Engineering Fluid Dynamics; Engineering Thermodynamics; Excitation; Excitation spectra; Fluid- and Aerodynamics; Heat and Mass Transfer; Laser induced fluorescence; Pulsed lasers; Research Article; Stimulated emission; Temperature dependence; Droplet Velocity; Motion Blur; Droplet Size; Wavelength Band; Excitation Intensity
• ISSN: 0723-4864; 1432-1114
• DOI: 10.1007/s00348-016-2253-2

In this work, a new measurement system is presented for studying temperature of micro-droplets by pulsed 2-color laser-induced fluorescence. Pulsed fluorescence excitation allows motion blur suppression and thus simultaneous measurements of droplet size, velocity and temperature. However, high excitation intensities of pulsed lasers lead to morphology-dependent resonances inside micro-droplets, which are accompanied by disruptive stimulated emission. Investigations showed that stimulated emission can be avoided by enhanced energy transfer via an additional dye. The suitability and accuracy of the new pulsed method are verified on the basis of a spectroscopic analysis and comparison to continuously excited 2-color laser-induced fluorescence.