| dc.description.abstract | The purpose of this research is to investigate particle mixture segregation behavior
inside a double-walled rotating drum using various particle mixture density ratios, rotation
speeds, and filling degrees. The motion of the granular materials was captured with a highspeed camera for image processing and analysis of particle segregation behavior inside the
drum. Particle positions, movements, velocities, fluctuations, and granular temperatures
were all measured.
The experimental results show that density ratios, rotation speeds, and filling
degrees have a significant impact on segregation in binary-density granular mixtures. The
results illustrate the phase segregation patterns including buoyancy effect (BE), mixing
state (MS), double segregation effect (DSE), phase transfer (PT), and reverse buoyancy
effect (RBE). Under the lowest value of density ratio with 1.75, the segregation could not
occur at any rotation speeds or filling degrees. A segregation pattern known as the
buoyancy effect (BE) is observed when the density ratio increase to greater than 3.19 and
the rotation speed is in a low value of Fr=0.5, in which the heavier particles migrate
towards the inner wall. While at Fr = 1, the segregation pattern for every density ratio
remains in the mixing state (MS). A double segregation effect (DSE) appears before
reaching the phase transfer (PT) zone. At higher rotational speeds, the phase segregation
pattern entering phase transfer (PT) zone before fully migrated to the outer wall. The
heavier particles fully move near the outer wall, resulting the reverse buoyancy effect
(RBE) at Fr = 4 for density ratios of 5.62 and 8.75. The result additionally demonstrates
that reducing the filling degree has a significant effect on hastening segregation behavior
for higher density ratios of 5.62 and 8.75. Increasing the density ratio would raise the
granular temperature of the particles. The highest granular temperature of heavy particles
occurs near the inner and outer side walls when Fr < 1 and Fr≥ 3.5, respectively.
Furthermore, the maximum granular temperature is found in the center of the drum space
at Fr = 1.5. When heavier particles approach both side walls, the lighter particles are
forced to move in the opposite direction. The outcomes of this study can be used in many
industrial processes, such as material density grading and different structures of
functionally graded materials.
Keywords : Rotating drum, Rotation speed, Density ratio, filling degree, Phase segregation
pattern, Granular temperature | en_US |