气固并流上行流动中颗粒均匀分布的稳定性

对气固并流上行流动中颗粒均匀分布的稳定性进行了分析.以颗粒运动学理论为基础,推导了偏离颗粒均匀分布状态的小扰动方程,并给出在扰动波长和颗粒体积分数为参数的空间上系统稳定的范围.由此发现，在颗粒浓度不太高的情况下，系统对于短波扰动是稳定的，对于长波扰动则是不稳定的.在表观气速较高的情况下，颗粒均匀分布状态几乎对所有扰动波都是不稳定的.当颗粒浓度很低时，只有波长很大的扰动才会使系统失稳，颗粒在某种程度上能保持均匀分布状态.当颗粒粒径小于某一临界值时，随颗粒粒径的增大，颗粒能保持均匀分布的浓度范围将减小；当颗粒粒径大于某一临界值时，随颗粒粒径的增大，颗粒能保持均匀分布的浓度范围将增大.物质密度较低的颗粒能在较大的颗粒浓度范围内保持均匀分布状态.

Stability Analysis on Particle Uniform Distribution in Cocurrent-up Gas-Solid Flow

The stability of particle uniform distribution in concurrent-up gas-solid flow is analyzed in this paper.The equations of small disturbances departing from the uniformity are derived on the basis of the particle kinetic theory.The stability ranges of the system on the parameters space of disturbance wavelength and the particle volume fraction are presented.It is found that the system is stable for the disturbances with very short wavelength and unstable for disturbances with longer wavelength unless the particle phase is very dense.The situation of particle uniform distribution can hardly be stable for all disturbances in the case of higher superficial gas velocity.When the particle phase is very dilute,only the disturbances with very long wavelength can drive the system unstable,the distribution of particles can remain uniformity to some extent.As the particle diameter increases,the range of particle concentration in which particle can distribute uniformly becomes narrower when the particle diameter is less than a critical value,while it will become wider when the particle diameter is larger.The particles with small density can distribute uniformly in a wider range of particle concentration.