The suitability of pulsed lasers for laser-induced-fluorescence (LIF) measurements of the local concentration of scalars in liquid-phase flows is investigated. Experiments were performed to measure the fluorescence intensity of aqueous solutions of rhodamine-6G chloride excited by a Q-switched, frequency-doubled, Nd:YAG laser. The fluorescence intensity is found to be linear with dye concentration, but not with illumination power density. The fluorescence intensity saturates at laser power densities easily exceeded by short-pulse-duration lasers. A procedure for calibrating and normalizing the raw image data is discussed which relies only on weak absorption and the linearity of fluorescence intensity with concentration. This procedure enables quantitative concentration measurement with pulsed-laser-induced fluorescence.
All Science Journal Classification (ASJC) codes
- Computational Mechanics
- Mechanics of Materials
- Physics and Astronomy(all)
- Fluid Flow and Transfer Processes