错位桨搅拌槽内污泥与固体颗粒混合过程的数值模拟

以直径1 m的搅拌槽为模型、含水率92%的污泥和粒径0.1 mm的固体颗粒为工作介质，采用Fluent软件对错位六叶螺旋桨搅拌下污泥与固体颗粒的混合过程进行数值模拟，通过与普通六叶螺旋桨对比，分析了2种桨型的浓度场分布、混合时间及单位体积混合能，并将计算的固体颗粒浓度分布与实验结果进行了比较. 结果表明，固体颗粒浓度分布计算结果和实验结果吻合较好，流动场分布对混合过程有一定影响，相同条件下错位桨搅拌的浓度场分布更快趋于稳定. 当转速N=4 r/s时，错位六叶螺旋桨的混合时间为27 s，比六叶螺旋桨的混合时间缩短9 s. 采用错位桨单位体积混合能仅为普通桨的79.6%，节能效果显著.

Numerical Simulation on Mixing Process of Sludge and Solid Particles in a Stirred Tank Equipped with Shifted Propeller

The granular sludge mentioned this paper in the 1m diameter stirred tank contains 92%(w) water and 0.01 m diameter solid granule. The numerical simulations of mixing processes of sludge and solid granule in the stirred tanks equipped with six shifted blades propeller (6SBP) and six blades propeller (6BP) were conducted respectively by using Fluent software. The numerical analysis of the concentration field distributions, the mixing times and the mixing energy per unit volume under the above two different propellers were carried out according to the simulation results, and the particles concentration distribution was demonstrated by experiment. The results show: the simulation curves of particles concentration distribution consists with the experimental one well. The mixing process is closely related to the flow pattern, and the concentration field distribution with shifted stirring blades tends to be stable faster. The 6SBP exhibits high perfomance in terms of mixing efficiency, the mixing time of six shifted blades propeller is 27 s at agitation speed of 4 r/s, while it costs 6BP 9 s more under the same condition. And the mixing energy per unit volume by six shifted blades propeller is only 79.6% of that by normal propeller.