论文部分内容阅读
网格拓扑方法直接影响到复杂结构的反应器内,气液两相数值模拟的收敛速度和计算精度。本文在引入中心下料管和环管式气体分布器的环流反应器内,通过实验,考察了不同表观气速下轴、径向局部气含率和气泡上升速度的分布特性。在此基础上,使用商业软件ANSYS CFX10．0,采用非结构化和杂交两种不同的网格拓扑方法,为该反应器作数值模拟。从定性角度来看,两者结果均表明内、外环气含率均随表观气速的增大而增大;外环循环流入内环的气泡量少;在同一表观气速下,外环气含率远远低于内环;内环气泡速度远远大于外环,这些规律与实验数据基本吻合。从定量角度来看,杂交网格法可清楚地反映出气体分布器和下料管液体入口的影响,以及外环气泡速度方向在导流筒外壁处向上,而这些却是非结构化网格法难以实现的。这说明了在该反应器内的气液两相数值模拟中,采用杂交网格法比单纯的非结构化网格法准确得多。因此,对于复杂几何结构的反应器,本文建议采用杂交网格法。
The method of grid topology directly affects the convergence speed and accuracy of the gas-liquid two-phase numerical simulation of the reactor with complex structure. In this paper, the distribution characteristics of axial and radial local gas holdup and bubble rising velocity under different apparent gas velocities are investigated experimentally in a loop reactor introduced with a central downcomer and a loop gas distributor. On this basis, commercial software ANSYS CFX10.0 was used to simulate the reactor by using two different unstructured and hybrid grid topology methods. From a qualitative point of view, the results of both show that the gas holdup of the inner and outer rings both increase with the increase of apparent gas velocity, and the amount of bubbles flowing into the inner ring is small with the outer ring; at the same superficial gas velocity, Outer ring gas holdup is much lower than the inner ring; inner ring bubble velocity is much larger than the outer ring, these laws are basically consistent with the experimental data. From a quantitative point of view, the hybrid mesh method clearly shows the effect of the gas distributor and the liquid inlet of the blanking tube and the velocity of the outer ring bubbles upward at the outer wall of the draft tube, whereas these are unstructured grid methods Hard to achieve. This shows that in the reactor gas-liquid two-phase numerical simulation, the use of hybrid mesh method is much more accurate than simple unstructured mesh method. Therefore, for the complex geometry of the reactor, the proposed hybrid mesh method.