| 摘要: | 本研究的目的是使用不同的顆粒混合物密度比、旋轉速度和填充度來研究雙壁
旋轉滾筒內顆粒混合物的偏析行為。實驗使用高速攝影機捕捉顆粒材料的運動，並
用影像處理技術分析滾筒內的顆粒動態行為，計算顆粒的位置、速度、擾動和顆粒
溫度。
實驗結果顯示，密度比、轉速和填充度對二元密度顆粒混合物的偏析有顯著影
響。兩種不同密度地顆粒發生的相分離的模式有浮力效應（BE）、混合態（MS）、
雙偏析效應（DSE）、相轉移（PT）和反浮力效應（RBE）。在密度比為最低值
（1.75）時，任何轉速或填充度下都不會發生偏析。當密度比增加時 (≥ 3.19)，在低
轉速之下(Fr=0.5)會觀察到一種稱為浮力效應 (BE) 的偏析模式，導致較重的顆粒向
內壁遷移。當轉速在 Fr = 1 時，每種密度比的偏析模式都仍處於混合狀態 (MS)。在
較高的旋轉速度下，相分離模式會先出現雙重偏析效應(DSE)，之後再隨轉速增加
而到達相轉移 (PT) 區域。在 Fr = 4 時，密度比為 5.62 和 8.75 會產生反浮力效應
(RBE)，亦即較重的顆粒會移動到外壁附近，同時，對於 5.62 和 8.75 這種較高的密
度比，降低填充度對加速偏析行為有顯著影響。另外，增加密度比會提高顆粒的顆
粒溫度。當 Fr <1 及 Fr ≥ 3.5 時，最大的重顆粒溫度分別出現在內壁及外壁附近；而
當 Fr = 1.5 時，最大的重顆粒溫度則出現在滾筒的中間區域。本研究的結果可以應
用於許多工業製程，例如材料密度分級和功能分級材料不同結構的處理。
關鍵字：轉鼓、轉速、密度比、填充度、相分離模式、顆粒溫度
;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 high speed 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 |
