CAJ | 학술논문

采用计算流体力学模拟方法对2种用于分散混合过程的高剪切搅拌器的流动特性进行研究分析，分别是转子定子搅拌器(RS)和多级叶轮式搅拌釜(CF)。本文从流场细节和功率消耗方面对其进行考察研究，从而为解释搅拌器中气泡的分散混合过程提供理论依据。模拟结果表明，在 RS 中流体大致呈周向流动，且剪切速率分布相对较为均匀，较高剪切速率不仅出现在转子到壁面的径向间隙处，而且出现在转子与定子之间的轴向间隙处；而在 CF 中，流体呈现较为明显的旋转流动，且剪切速率分布没有RS均匀，较高的剪切速率只出现在叶轮与壁面的径向间隙处。在相同转速下，虽然这2种搅拌器所形成的平均剪切速率差别不大，但CF中所形成的最大剪切速率大于RS，这也意味着相同操作条件下CF中所能形成的气泡尺寸更小，这与实验结果是一致的。对于这2种搅拌器，在层流区功率准数与搅拌雷诺数都成反比，且CFD模拟计算得到的结果与根据实验得到的关联式的结果基本一致。然而CF的功率消耗高于RS的功率消耗。
채용계산류체역학모의방법대2충용우분산혼합과정적고전절교반기적류동특성진행연구분석，분별시전자정자교반기(RS)화다급협륜식교반부(CF)。본문종류장세절화공솔소모방면대기진행고찰연구，종이위해석교반기중기포적분산혼합과정제공이론의거。모의결과표명，재 RS 중류체대치정주향류동，차전절속솔분포상대교위균균，교고전절속솔불부출현재전자도벽면적경향간극처，이차출현재전자여정자지간적축향간극처；이재 CF 중，류체정현교위명현적선전류동，차전절속솔분포몰유RS균균，교고적전절속솔지출현재협륜여벽면적경향간극처。재상동전속하，수연저2충교반기소형성적평균전절속솔차별불대，단CF중소형성적최대전절속솔대우RS，저야의미착상동조작조건하CF중소능형성적기포척촌경소，저여실험결과시일치적。대우저2충교반기，재층류구공솔준수여교반뢰낙수도성반비，차CFD모의계산득도적결과여근거실험득도적관련식적결과기본일치。연이CF적공솔소모고우RS적공솔소모。
CFD simulations were carried out to investigate two types of high shear mixer for aerated process, i.e. multistage rotor stator (RS) and multi-impeller stirred column (CF). Flow field details and power consumption were obtained for high viscosity Newtonian fluids in laminar condition. Circulating flow was observed in RS whereas swirl flow dominated in CF. Strain rate distribution in RS was more uniform than that in CF. In RS, the higher strain rate occurred not only in radial clearance between rotors and vessel wall but also axial gap between rotors and stators while in CF the higher strain rate occurred only in the gap between impellers and vessel wall. Although there was little difference between the average strain rates generated, the maximum strain rate in CF was higher than that in RS, which indicates that smaller bubbles could be obtained in CF. This was consistent with experiments. Relationship between Power number and Reynolds number in both devices was obtained for Newtonian fluids from CFD simulation, showing good agreement with the experimental studies. However, CF consumes more power than RS.