Numerical and experimental analysis of particle-laden duct flows subject to radiation*

Fluctuations of particle concentration arising from particle-turbulence interaction lead to system characteristics that differ from predictions based on homogeneous concentration distributions. In particle-solar-receivers small and heavy particles advected by a turbulent stream absorb the solar radiation and heat the surrounding gas. Particle clustering gives rise to gas temperature fluctuations and modulates the radiation transmitted across the system. A turbulent square duct laden with inertial particles and exposed to monochromatic radiation through one of the walls is studied computationally and experimentally to gain insights on the coupling between particles, turbulence and radiation. Results are analyzed at various particle loadings for a bulk Reynolds number Re_H=20000 and a Stokes number St_k=5. DNS of the gas and point-particle Lagrangian tracking with a deterministic collision model are combined with discrete ordinate methods for the radiation solver. Laser based techniques and flow probes provide particle concentration and velocity, gas temperature and radiation transmission statistics, as well as their correlations. The necessity of tailored post-processing for a one-to-one comparison of results is evidenced.