进口气速对水力喷射-空气旋流器内湍动能分布影响

The influence of air inlet velocity on the distribution of turbulent kinetic energy in a water-sparging aerocyclone

依据耦合强化思路,提出了利用水力喷射-空气旋流模式强化高浓度氨氮废水的脱除过程,研发出一种水力喷射-空气旋流器(WSA)。WSA作为一种典型的气液传质设备,其内部流体的湍动行为分布研究对反应器的设计与优化尤为重要。为此,利用雷诺应力模型(RSM)描述反应器内复杂的气液旋转流动、局部回流及具有速度方向各异性的湍流行为。针对反应器内的多相流动,采用VOF模型计算气液两相流动中相交界面的变化规律。最后,基于模拟计算结果,分析水力喷射-空气旋流器内湍动能分布规律。结果表明:溢流管底部下轴向位置上湍动能分布具有相似性,呈两边高中间低的不对称鞍形。溢流管区域内的湍流从时均流中获得的能量较多,时均流在该区域的能量损失于湍流的量较大,特别是在溢流管轴向向下段区域。

According to the idea of coupling enhancement, the removal process of high concentration ammonia nitrogen wastewater is improved by using hydraulic jet air cyclone mode, and then a water sparging aerocyclone(WSA) is developed. A WSA is a typical gas-liquid mass transfer device, and the research on the turbulent behavior distribution of its internal fluid is particularly important for the design and optimization of the reactor. For this reason, the Reynolds Stress Model(RSM) is used to capture the complex gas-liquid rotational flow, local reflux, and anisotropy of the radial velocity in the reactor. For multiphase flow in the reactor, the Volume of Fluid(VOF) model is used to capture the change law of the intersection interface of gas-liquid two-phase flow. Finally, based on the simulation results, the distribution of turbulent kinetic energy in the WSA is obtained. The results show that the distribution of the turbulent kinetic energy in the lower axial position of the bottom of the overflow pipe is similar, showing an asymmetric saddle shape with high on both sides and low in the middle. The turbulent flow in the overflow pipe area obtains more energy from the time-averaged flow, which means the energy loss of the time-averaged flow in this area is greater than that of turbulence, especially in the axially downward section of the overflow pipe.