摘要
采用PDA对三种不同颗粒质量载荷的竖直向下圆管突扩流动进行了测量,发现在剪切较强的突扩发展区中气相脉动速度与速度梯度存在线性关系。采用强剪切流假设,进一步对管流中气相湍流的理论推导得到了与实验结果一致的结论.理论分析表明,颗粒浓度较小时,颗粒对气相湍流作用较弱,单相流中气相脉动速度与速度梯度的线性关系得以保持.同时推测,当增大颗粒浓度,颗粒对气相湍流的非线性作用增大,气相脉动速度与速度梯度的线性关系消失.对经典文献中的实验数据进行分析,验证了以上推论。
Flow velocities were measured in gas-solid two-phase flows with different particles mass loadings in a vertical sudden-expansion pipe. The results show that, a linear relationship exists between the gas fluctuation velocities and velocity gradients in the sudden expansion region where the shear is intense. A theoretical derivation of the gas turbulence in a round pipe flow proves the previous conclusion. Analysis shows that, the particles have little influence on the gas turbulence as the particles concentration is small and thus the linear relationship between the gas fluctuation velocities and velocity gradients retains as in the single-phase flow. It is also prospect that, the nonlinear effects of particles on the gas turbulence become important as the particles concentration increases, thus the relationship between the gas fluctuation velocities and velocity gradient will disappear. An analysis of the experimental data in classical literature proves the deduction.
出处
《工程热物理学报》
EI
CAS
CSCD
北大核心
2008年第4期621-624,共4页
Journal of Engineering Thermophysics
基金
国家重点基础研究规划(973)项目(No.2006CB2003)
关键词
气固两相流
脉动速度
速度梯度
突扩流动
PDA
gas-solid two-phase flow
fluctuation velocity
velocity gradient
sudden-expansion flow
PDA
