水平管入口段内水煤浆流动特性数值模拟

以Eulerian多相流方法为基础建立了水煤浆流动的液固两相流体动力学模型,并对水平管入口段内水煤浆流动进行了模拟.模型采用颗粒动理学理论求解固相本构方程,采用RNGk-ε湍流混合模型描述颗粒间具有强烈作用的两相湍流流动.针对水煤浆中煤粉颗粒的双峰分布特性,将煤粉看作2种大小不同的固相,同时考虑固相与液相、固相与固相之间的动量交换.模型有效性通过Kaushal等试验结果和水煤浆的压降试验验证.通过模拟考察了入口段内速度及浓度分布过程和入口段长度的变化规律.结果表明:重力和颗粒间的相互作用对浓度和速度分布过程具有重要影响;固相体积分数在30%~49.5%范围内,入口段长度随浓度的增加而减小,随平均流速(0.2~5.0m/s)先增加后减小.

Numerical study of developing coal-water slurry flow in entrance region of horizontal pipe

An Eulerian multi-fluid flow model is developed to carry out a numerical study on coal-water slurry flow in the entrance region of horizontal pipe.The kinetic theory of granular flow is used to calculate constitutive equations of the solid-phase components and the RNG k-ε turbulent model is incorporated into the governing equation to model turbulent two phase flow with strong particle-particle interactions.In this model,the coal particles with bimodal distribution are considered as two solid-phase components and the moment exchange between solid and liquid phase as well as that between solid and solid phase are taken into account.The model was validated with Kaushal experimental experiments.The numerical investigations focus mainly on the developing processes of volume fraction and velocity distributions in the entrance region as well as the entry length.The results show that the gravitational force and the strong particle-particle interaction have significant effects on concentration and velocity distribution profile.The entry length decreases as solid concentration increases from 30% to 49.5% and for the same slurry,the entry length firstly increases and then decreases when the inlet velocity increases from 0.2 to 5.0 m/s.