非标准挡板搅拌槽内湍流流场的数值模拟

Study on the Hydrodynamics of a Stirred Tank Equipped with Non-Standard Baffles

采用分离涡模型研究了非标准挡板搅拌槽内的流体力学特性,利用滑移网格法模拟了搅拌桨与挡板之间的相对运动。在验证了模拟方法有效性的基础上,分析了挡板布置方式对搅拌槽内的流场、速度与湍动能分布以及功率消耗的影响。结果表明,挡板布置方式对搅拌槽内的流场结构影响较小,但会改变桨叶射流的方向;对速度大小有一定的影响,完全非对称布置时的速度分布最均匀;搅拌功率随挡板非对称程度的增大略有提高,标准挡板的功率消耗与夹角为20°时的功率消耗非常接近,而且标准挡板时的湍动能最大,优于非标准挡板布置方式。

The hydrodynamics of a stirred tank equipped with non-standard baffles was studied by using the detached eddy simulation （DES） model. The sliding mesh method was used to simulate the relative motion o between the impeller and baffles. After verifying the simulation method by comparing with the experimental results, the effects of baffle arrangement on the flow field, distributions of velocity and turbulent kinetic energy and the power consumption were studied. Results show that the arrangement of the baffles has little effect on the overall flow pattern, but it will change the impeller discharge flow direction. Baffle arrangement affects the distribution of the velocity components, but the trend of the effect is not always the same in different regions of the stirred tank. The velocity distribution in the stirred tank with the completely asymmetric baffle arrangement is the most uniform one. The power consumption increases with the increase of the baffle asymmetric degree, with the exception of the standard baffle arrangement, its power comsumption is nearly the same as that of the baffle arrangement with the baffle adjacent angle of 20°. As far as the turbulent kinetic energy, the standard baffle arrangement is the best, which has bigger energy profiles than other baffle arrangements.