High velocity infrared thermography and numerical trajectories of solid particles in compressible gas flow

Lappa, M. and Esposito, A. and Aponte, F. and Allouis, C. (2019) High velocity infrared thermography and numerical trajectories of solid particles in compressible gas flow. Powder Technology, 343. pp. 671-682. ISSN 0032-5910 (https://doi.org/10.1016/j.powtec.2018.11.059)

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Abstract

The use of High Velocity Infrared Thermography as a valuable alternative to other existing techniques for the visualization and tracking of solid particles transported by a gas jet has been assessed by considering different situations in terms of problem characteristic numbers (jet Reynolds and Mach numbers and Particle Stokes and gravitational Froude numbers). Particles paths have also been calculated by means of a hybrid Eulerian-Lagrangian technique under the intent to cross-validate the two (experimental and numerical) approaches. The results indicate that such a strategy is robust and sufficiently flexible to be used in relatively wide regions of the space of parameters. Experiments have clearly demonstrated that thermography can properly capture particle dynamics with a level of detail comparable to that provided by simulations. Computations have proved to be valuable on their own by allowing the explorations of regions of the parameters space otherwise out of reach. Different tests have been conducted considering both isolated particles and “swarms”. We show that the observed dynamics are induced by the delicate interplay of different effects, including inertial, gravitational and eventually “lift” contributions produced by a non-perfect horizontal orientation of the jet or other uncertainties (such as those due to a non mono-sized set of particles).

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