Model for induced airflow velocity of falling materials in semi-closed transfer station based on similitude theory

摘要

The dimensionless parameters of a pipe flow's Reynolds number (Re), mass flow-rate number (m(p)/(mu D)), specific induced airflow number (rho(p).(u(g)D(2)/m(p))), height number (h/D), and granular-flow number (Gr) were obtained by using the Pi theorem. The influences of m(p)/(mu D), rho(p).(u(g)D(2)/m(p)), and h/D to the Re were explored by similitude experiments. Finally, the semi-empirical model of induced airflow velocity was established through the Gr and Re. The conclusions are as follows: in the semi-closed transfer station, the Re value increased with the increase of the m(p)/(mu D) value. Due to the interaction among the particles and change of the specific flow space of the blanking tube on the specific induced air flow, the rho(p).(u(g)D(2)/m(p)) value was found to be proportional to the m(p)/(mu D) value raised to the power of approximately -0.73. Due to limitations of drop heights, particles should be in the acceleration phase from beginning to end, when the resistance drag of the particles is less than the gravity of itself. It was also discovered that the Re value is proportional to the h/D value raised to the power of approximately 0.88. Additionally, similitude experiment results revealed that the Re value is proportional to the Gr value raised to the power of approximately 0.27. On this basis, the semi-empirical model for induced airflow velocity was established. The model can forecast actual values accurately with a deviation of the calculated values limited to plus or minus 10%. These research results can benefit industries in their transfer station dust control systems and in the design of ventilation systems. (C) 2014 The Society of Powder Technology Japan. Published by Elsevier B. V. and The Society of Powder Technology Japan. All rights reserved.