Planar laser-induced fluorescence, PLIF

There are many nonintrusive experimental tools available that can help scientists to develop a good picture of fluid dynamics and transport in chemical reactors. Laser Doppler velocimetry (LDV), particle image velocimetry (PIV) and sonar Doppler for velocity measurement, planar laser induced fluorescence (PLIF) for mixing studies, and high-speed cameras and tomography are very useful for multiphase studies. These experimental methods combined with computational fluid dynamics (CFDs) provide very good tools to understand what is happening in chemical reactors. 

Note that when solving the CFD transport equations, the mean velocity and turbulence state variables can be found independently from the mixture-fraction state variables. Likewise, when validating the CFD model predictions, the velocity and turbulence predictions can be measured in separate experiments (e.g., using particle-image velocimetry [PIV]) from the scalar field (e.g., using planar laser-induced fluorescence [PLIF]). 

The improvement in accuracy achieved by the complex closures compared to the simpler ones can also be questionable. Osenbroch ]67] and Mortensen ]60] successfully applied the combined particle image velocimetry (PIV)/planar laser induced fluorescence (PLIF) technique to measure the instantaneous velocity and reacting species concentration in mixing devices like a mixing channel, pipe, and multi-functional channel reactor. The measured... 

Figure 24 shows the evolution of the CN concentration field. A noticeable amount of CN is observed at t > 7 ms. The concentrations of CN are usually small, except in the secondary flame, thereby serving as a good indication of the flame position. Parr and Hanson-Parr [23] conducted pioneering measurements of the transient flame structure of RDX using both UV-visible absorption and non-intrusive planar laser-induced fluorescence (PLIF). The experiments were... 

The laser-based techniques currently being used and developed include vibrational Raman scattering, coherent anti-Stokes Raman scattering (CARS), Rayleigh scattering, laser-induced fluorescence, and planar laser-induced fluorescence (PLIF). This is an active research field at various research establishments. Laser-induced fluorescence spectroscopy has been used to measure several combustion intermediates, for example, CH, C2, HCH, OH, NO, NO2, HNO, CO, halogenated hydrocarbons, and polycyclic aromatic hydrocarbons. 

Cross-correlation cameras are available with resolutions up to 2 k x 2 k pixels, and framing rates up to 30 Hz 8 bit cameras are sufficient for most purposes. However, 12 bit cameras are becoming common, especially for applications such as planar laser-induced fluorescence (PLIF), where extra sensitivity and dynamic range are required. 

Spray properties are mostly determined with optical measurement techniques. For the analysis of the droplet diameter Shadowgraphic methods, laser diffraction or Phase Doppler Anemometry (PDA) have been used elsewhere [1, 2, 11, 18]. Droplet velocities can be measured with Shadowgraphy, Particle Image Velocimetry (PIV), or PDA [1, 6, 19]. The determination of the spray temperature is possible with Global Rainbow Thermometry (GRT), Planar Laser Induced Fluorescence (PLIF), and Differential Infrared Thermography (DIT) [20-22]. 

Industrial Applications Fiber optic sensor for sol-gel material planar laser-induced fluorescence (PLIF) measurements in aqueous flows ... 

Another technique used to study oxy-fuel burners is Chemically Sensitive-Planar Laser Induced Fluorescence (CS-PLIF) [15]. The CS-PLIF is a noninvasive, quantitative method for visualizing flow, mixing, and chemical reactions in complex geometries typical of commercial furnaces. The technique provides information on burner/bumer interactions, bumer/wall interactions, and burner interactions with the furnace flowfield/recir-culation pattern. 

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