鱼尾型搅拌桨设计及在羧甲基纤维素钠溶液中的应用

Design of Fishtail Turbine and Its Application in the Sodium Carboxymethyl Cellulose Solution

搅拌桨是生物反应器的核心部件,直接影响反应釜内流体的搅拌混合和气液分散性能.基于双色刺尻鱼(Centropyge Bicolor)尾鳍轮廓特征和仿生学原理,设计了一种鱼尾型搅拌桨—FT桨(Fishtail Turbine),应用于羧甲基纤维素钠(CMC)溶液的搅拌混合操作.结合计算流体动力学(CFD)和粒子图像测速(PIV)技术,研究了FT桨在纯水、 CMC溶液中的搅拌混合和气液分散性能,并与传统RT桨(Rushton Turbine)进行了对比.结果表明:(1)对于单相流,与RT桨相比,FT桨能增大流场速度、湍动能作用区域;搅拌纯水、 0.25%CMC溶液、 0.5%CMC溶液时,湍动能最大值分别增加39.47%、 23.33%、 18.31%,平均增加31.03%.(2)对于气液两相流,与RT桨相比,FT桨能增大高气含率区域,促进气液分散;搅拌气液两相纯水、 0.25%CMC溶液、 0.5%CMC溶液时,总体气含率分别相对增加8.62%、 9.19%、 2.58%,平均相对增加5.94%,搅拌功耗分别降低4.58%、 4.54%、 4.98%,平均降低4.70%.与RT桨相比,FT桨搅拌CMC溶液具有更优的搅拌混合和气液分散性能,应用前景广阔.

The mixing paddle,as the core component of bioreactors,directly affects the mixing performance and gas-liquid dispersion performance of the fluid in the bioreactor.According to the contour characteristics of the tail fins of centropyge bicolor,the fishtail turbine(FT turbine)was designed based on bionics.Then the FT turbine was applied to the mixing operation of the sodium carboxymethyl cellulose(CMC)solution.The combination of computational fluid dynamics(CFD)and particle image velocimetry(PIV)was employed to study and compare the mixing performance and gas-liquid dispersion performance of FT turbine and traditional rushton turbine(RT turbine)in pure water and CMC solution.The results showed that:①In the single-phase flow,compared with the RT turbine,the FT turbine enhanced the flow field velocity and turbulent kinetic energy mixing areas.When stirring pure water and CMC solution with mass fraction of 0.25%and 0.5%,the maximum values of the turbulent kinetic energy were increased by 39.47%,23.33%and 18.31%,respectively,with an average increase of 31.03%.②In the gas-liquid two-phase flow,compared with the RT turbine,the FT turbine increased the high gas holdup area and promoted the gas-liquid uniform dispersion.When stirring the gas-liquid two-phase flow of pure water and CMC solution with mass fraction of 0.25%and 0.5%,the overall gas holdup was relatively increased by 8.62%,9.19%and 2.58%,respectively,with an average relative increase of 5.94%,and the agitation power consumption was decreased by 4.58%,4.54%and 4.98%,respectively,with an average decrease of 4.70%.The FT turbine has better mixing performance and gas-liquid dispersion performance and wider application prospects than RT turbine when mixing the CMC solution.