摘要
通过实验研究和理论分析,考察了提升管中颗粒相的质量守恒;发现在传统的两相流研究中,对颗粒速度的时间平均和算术平均存在着误用。在传统理论中,由于引入了颗粒相的体积分率项,实际上是对离散的颗粒进行了连续化的假设。由此不可避免地造成颗粒速度时间平均和算术平均的混淆。在微观尺度上对气/液-固两相流中颗粒速度时间平均的物理意义进行了分析,给出了计算非连续流场中颗粒时均速度的表达式,并提出了分析颗粒相质量守恒的方法。
Gas/liquid-solid two-phase flow is ubiquitous in chemical engineering.This paper theoretically and experimentally analyzes the mass conservation of solid phase in a CFB riser.It is revealed that the time-average particle velocity and arithmetical-average particle velocity are misused in the traditional viewpoint of two-phase flow.The introduction of solid volume fraction in a two-phase flow actually denotes an assumption that the discrete particles are treated as a continuum.Then the misuse of time-average particle velocity and arithmetical-averaging appears inevitable.The physical meaning of time-average particle velocity in a gas/liquid-solid two-phase flow is discussed on a microcosmic scale.An equation for computing the time-average particle velocity in a discrete two-phase flow is given.Furthermore,a proper approach is proposed to analyze the mass conservation of discrete particles.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2010年第9期2217-2224,共8页
CIESC Journal
基金
国家自然科学基金项目(20776155)~~
关键词
两相流
颗粒速度
质量守恒
时间平均
算术平均
two-phase flow
particle velocity
mass conservation
time-average
arithmetical-average
