A Dynamic Model for the Normal Impact of Fly Ash Particle with a Planar Surface

The rebound behavior of fly ash particles normally impacting a planar surface is investigated by using a dynamic model. The three forms of soft sphere physical model are obtained using static/quasi-static contact mechanics and energy dissipation theory. The influences of the particle size, the incident velocity of the particle on the damping coefficient and the impact contact time are all examined. We also predict the critical velocity for three particle sizes. It is found that the variation of the damping coefficient (η) with the normal incident velocity (<i>v_in</i>) can be roughly divided into the three parts. In the first part, η decreases with increasing <i>v_in</i>. In the second part, η is little changed with increasing <i>v_in</i>. In the third part, η rapidly increases with increasing <i>v_in</i>. For smaller impact velocities, the viscoelastic effect plays a dominant role in the impact process, while for higher incident velocities; the energy dissipation depends mainly on plastic deformation. In addition, the critical velocity shows a distinct dependence on the particle size. Finally, the contact displacement-contact time curves are examined. The work provides a solid basis for the development of a discrete-element-method approach to study ash deposition.