INVESTIGADORES
NIGRO Norberto Marcelo
congresos y reuniones científicas
Título:
Numerical Simulation of Solid Particle Deposition in Ducts
Autor/es:
STORTI MARIO; NIGRO NORBERTO; PAZ RODRIGO; DALCIN LISANDRO
Lugar:
San Luis, Argentina
Reunión:
Congreso; ENIEF 2008; 2008
Institución organizadora:
Universidad Nacional de San Luis
Resumen:
              Solid-gas multiphase flows are present in many industrial processes as, for instance, theventilation system of sinterization plants. One of the most important results from the practical pointof view for the transport of particles in ventilation ducts is the prediction of deposition rates. Largeparticles in ventilation ducts tend to fall quickly and to accumulate in a saltation layer near the lowersurface of the duct. When the particle flux in the saltation layer exceeds a given threshold which dependson the shear stress, the particles begin to accumulate and a deposited layer growths. If this layer growthstoo much its weight may cause the collapse of the supporting structure. For small particle diameterthe Eulerian/Eulerian approach is useful because the characteristic times in which the particle velocityreaches the equilibrium velocity is small. In this case a system of PDE’s is solved for each phase. Whenthe particle diameter is very small the Algebraic Slip Model is appropriate, whereas for a moderatediameters the momentum equation of the solid phase must be solved and the Two-Fluid Model is moreappropriate. When the particles are large, and consequently the characteristic time is large, they behavealmost independently of the fluid, and terms like particle inertia, virtual mass, lift, and Magnus effectare important. This effects are difficult to cast as terms in the momentum equation as PDE’s through anaverage process and then the Lagrangian approach where each particle trajectory is solved as an ODEis more appropriate. Moreover, the resulting system of equations may be ill posed. In addition, someeffects related with the interaction of particles with solid boundaries, like bouncing, lift-off and slidingcan be treated almost uniquely in the Lagrangian formulation. In this article the implementation ofan Eulerian/Lagrangian formulation for the transport of moderate to large solid particles is described.The implementation includes an efficient tracking of particles through unstructured moving meshes, theSchiller-Naumann drag model, and partially elastic collision with solid surfaces. Deposition rates canbe computed in terms of the particle flux in the saltation layer and the shear stress at the wall. Severalexamples in ventilation ducts for industrial sinterization plants are presented.