TED-AJ03-259 NUMERICAL INVESTIGATION OF MULTIPLE GAS-PARTICLE IMPINGING JETS HEAT TRANSFER USING FRACTAL MODEL

概要

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The calculation is performed by using κ-ε turbulence model in which the particle source terms described turbulence modulation due to particles and Lagrange model for discrete particle motion with Direct Simulation Monte Carlo method and fractal model to express the particle coagulations, collisions and breakups. As the adhesion forces between the particles, viscous force and capillary force are considered. The critical Stokes numbers for coagulation and breakup and Capillary number are used as switches of working the adhesion forces. When the initial particle size distribution is uniform, flow and heat transfer characteristics of both phases are independent of coalescence. If the initial size distribution has many small particles (Dist-S), the enhancement of turbulent energy due to particles becomes dominant as the heat transfer enhancement mechanism. On the contrary, the increase of heat capacity by added particles mainly promotes the heat transfer if many large particles initially involved (Dist-L). The size distribution makes large difference of heat transfer between both nozzles. If many small particles involved, the heat transfer is promoted while enhancement of heat transfer is promoted while enhancement of heat transfer and turbulent energy is prevented by the highly concentrated belt-like region of particles of many large particles involved.[figure]
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