Alexander Albert, Shinbrot Troy, Johnson Barbara, Muzzio Fernando J
Department of Chemical and Biochemical Engineering, Rutgers University, Piscataway, NJ 08855, USA.
Int J Pharm. 2004 Jan 9;269(1):19-28. doi: 10.1016/s0378-5173(03)00296-5.
Stable segregation patterns are shown to form in V-blenders over a wide range of vessel capacities, fill levels, and rotation rates. Slight changes in either rotation rate or fill level induce changes in pattern formation. Trajectory segregation in two regions of the flow, accumulating over many flow periods, drives segregation pattern formation. Scaling criteria derived to relate particle velocities to vessel size and rotation rate in rotating cylinders successfully predict the rotation rate for the transition between patterns across V-blenders of 0.8-26.5 quart total capacity. This agreement suggests that pattern formation is governed by the magnitude of particle velocities. Regardless of vessel size, when particle velocities at specific regions of the blender are below a certain value, one particular pattern appears, and when they increase beyond that speed (i.e. by changing the rotation rate or the vessel size), a different pattern emerges. A scaling relation between segregation pattern formation and blender fill level was not identified because the complex flow patterns in the V-blender (the length of the flowing layer and the mixture center of mass relative to the blender are constantly oscillating) preclude the determination of a relationship between blender fill level and particle velocities.
结果表明，在各种容器容量、填充水平和转速条件下，V型混合器中都会形成稳定的分离模式。转速或填充水平的微小变化都会引起模式形成的变化。在两个流动区域中的轨迹分离，在多个流动周期内不断累积，驱动了分离模式的形成。通过推导得出的比例准则，将旋转圆筒中颗粒速度与容器尺寸和转速联系起来，成功地预测了总容量为0.8 - 26.5夸脱的V型混合器中模式转变的转速。这种一致性表明，模式形成受颗粒速度大小的控制。无论容器尺寸如何，当混合器特定区域的颗粒速度低于某个值时，会出现一种特定模式；当颗粒速度超过该速度（即通过改变转速或容器尺寸）时，则会出现不同的模式。由于V型混合器中复杂的流动模式（流动层的长度和相对于混合器的混合质心不断振荡），无法确定混合器填充水平与颗粒速度之间的关系，因此未确定分离模式形成与混合器填充水平之间的比例关系。
