Shigeru Kuchii

Flushing phenomenon of fine powder

Abstract When a load is applied to a free surface of cohesive fine powder in a vessel, the powder can spurt from a small orifice, which we call the flushing. A gas–solid two-phase flow model using Darcys law examines this phenomenon. The numerical simulation by this model is qualitatively verified by the measurement for a case when the powder in a rectangular vessel spurts from a slit by a constant piston load. It is found that near the slit, there appears a high-speed region of particle of which velocity is considerably larger than that of free-flowing due to the gravity.

Interstitial fluid pressure and voidage in flushing phenomenon of fine powders

Fine powders were flooded out of a small side orifice near the bottom of a cylindrical vessel by a piston load exerted on the top surface. It is found that there is a unique relationship for each powder between the interstitial fluid pressure and voidage at the onset and end of flushing, independent of the piston load and the initial voidage, and that powder with a small relaxation time easily gives rise to flushing.

Numerical Analysis and Experimental of Flushing Phenomenon of Fine Particles.

We propose a theory for flushing phenomenon of fine particles based on gas-solid two phase model and by using SOLA-VOF method calculate flow of gas and particle when an external load is applying to powder surface. In order to examine the flow near the onset of flushing phenomenon, we omit the effective stress since numerical calculation.