多层新型桨搅拌槽内气-液两相流动的实验与数值模拟

Experimental Study and Numerical Simulation of GasLiquid Flow in a Stirred Tank with a New Multiple Impeller

对三层新型组合桨气-液两相搅拌槽内的流体流动进行了实验研究,并采用计算流体力学(CFD)的方法对气-液两相搅拌槽的通气搅拌功率、流场、局部气含率及总体气含率进行了数值模拟,数值模拟采用了欧拉-欧拉方法,数值模拟结果与实验值吻合良好,同时考察了通气流量和搅拌转速对通气搅拌功率和气含率的影响规律.研究结果表明,欧拉-欧拉方法能较好地模拟搅拌槽内气-液两相流的流动状况.

The fluid flow in a gas-liquid stirred tank of 0.476 m diameter with triple impellers was experimentally investigated and numerically simulated. The Eulerian-Eulerian formulation, standard k-e turbulent model and multiple frames of reference （MFR） method were used in the simulation. The newly developed four-half-elliptical-hollow-blade disk turbine （HEDT） was used as the bottom impeller to disperse the incoming gas, and two upward-pumping four-wide-blade hydrofoil （WHo） impellers were used as middle and top impellers to insure the homogenous mixing fi-om the top to bottom in the tank. The power number, gassed power demand and overall gas holdup predicted by CFD are in good agreement with the experimental data. The local gas holdup distribution is mainly controlled by the flow field. There is a region with very high local gas holdup just above the top impeller and near the tank wall, which is in agreement with the literature. The results are of importance to the optimization of industrial stirred tank reactors.