The effect of the inlet conditions on the numerical solutions of particle-gas flows

摘要

The effect of the conditions under which particles enter a vertical pipe on the flow patterns was investigated numerically by means of a commercial CFD code('FIDAP').Two different methods of introducing the same mass flow rate of particles are examined.In the first method,we alter the number and locations of the feeding point at the cross-section of the pipe entrance.To test this method.we analyzed six cases,which are presented by appropriate combinations of the number of feeding localions and the frequency of injection at each feeding point. In the second method,we employed an artificial inlet volume in which the feeding points were distributed randomly.We tested six cases of different combinations of the length of an artificial inlet volume and the number of random feeding locations for that volume.Although the conveying conditions for all the cases were the same,the inlet conditions of the particles significantly affected both the gas and the particle velocity distributions in the pipe.On the other hand,the random introduction of particles by an optimal feeding volume(the second method)dramatically improved the homogeneity of particle dispersion at the entrance to the pipe.an artificial inlet volume in which the feeding points were distributed randomly.We tested six cases of different combinations of the length of an artificial inlet volume and the number of random feeding locations for that volume.Although the conveying conditions for all the cases were the same,the inlet conditions of the particles significantly affected both the gas and the particle velocity distributions in the pipe.On the other hand,the random introduction of particles by an optimal feeding volume(thesecond method)dramatically improved the homogeneity of particle dispersion at the entrance to the pipe.