机械工程学报
機械工程學報
궤계공정학보
Journal of Mechanical Engineering
2015年
16期
185-195
,共11页
梁瑛娜%高殿荣%拜亮
樑瑛娜%高殿榮%拜亮
량영나%고전영%배량
搅拌槽%计算流体力学(Computational fluid dynamics,CFD)%层流模型%混合时间%示踪剂
攪拌槽%計算流體力學(Computational fluid dynamics,CFD)%層流模型%混閤時間%示蹤劑
교반조%계산류체역학(Computational fluid dynamics,CFD)%층류모형%혼합시간%시종제
stirred tank%computational fluid dynamics(CFD)%laminar model%mixing time%tracer
采用Laminar模型、多重参考系法(Multiple reference frame，MRF)和示踪剂浓度法对双层六直叶桨搅拌槽内高黏非牛顿流体层流流场和混合时间进行数值模拟，分析其流动特性、示踪剂扩散过程、示踪剂浓度响应曲线和混合时间；采用示踪粒子法和酸碱指示剂变色法对透明有机玻璃搅拌槽内流动场和混合过程进行试验测定。结果表明，双层桨中间面将示踪剂先控制在加料的半层内随主体介质流动扩散，当浓度差增大后再向另外半层扩散；在搅拌剧烈的桨叶区或在中间面加入示踪剂，可获得更短的混合时间；不同位置混合完成的时间不同，根据搅拌要求合理选择监测点，可避免资源浪费或搅拌不充分；提高搅拌转速，可使搅拌槽内介质混合过程加快，混合时间减小；试验结果验证了数值模拟结果的准确性，为非牛顿流体层流搅拌槽的设计和工程应用提供了理论依据。
採用Laminar模型、多重參攷繫法(Multiple reference frame，MRF)和示蹤劑濃度法對雙層六直葉槳攪拌槽內高黏非牛頓流體層流流場和混閤時間進行數值模擬，分析其流動特性、示蹤劑擴散過程、示蹤劑濃度響應麯線和混閤時間；採用示蹤粒子法和痠堿指示劑變色法對透明有機玻璃攪拌槽內流動場和混閤過程進行試驗測定。結果錶明，雙層槳中間麵將示蹤劑先控製在加料的半層內隨主體介質流動擴散，噹濃度差增大後再嚮另外半層擴散；在攪拌劇烈的槳葉區或在中間麵加入示蹤劑，可穫得更短的混閤時間；不同位置混閤完成的時間不同，根據攪拌要求閤理選擇鑑測點，可避免資源浪費或攪拌不充分；提高攪拌轉速，可使攪拌槽內介質混閤過程加快，混閤時間減小；試驗結果驗證瞭數值模擬結果的準確性，為非牛頓流體層流攪拌槽的設計和工程應用提供瞭理論依據。
채용Laminar모형、다중삼고계법(Multiple reference frame，MRF)화시종제농도법대쌍층륙직협장교반조내고점비우돈류체층류류장화혼합시간진행수치모의，분석기류동특성、시종제확산과정、시종제농도향응곡선화혼합시간；채용시종입자법화산감지시제변색법대투명유궤파리교반조내류동장화혼합과정진행시험측정。결과표명，쌍층장중간면장시종제선공제재가료적반층내수주체개질류동확산，당농도차증대후재향령외반층확산；재교반극렬적장협구혹재중간면가입시종제，가획득경단적혼합시간；불동위치혼합완성적시간불동，근거교반요구합리선택감측점，가피면자원낭비혹교반불충분；제고교반전속，가사교반조내개질혼합과정가쾌，혼합시간감소；시험결과험증료수치모의결과적준학성，위비우돈류체층류교반조적설계화공정응용제공료이론의거。
The laminar model, the multiple reference frame(MRF) and the tracer concentration method are employed to simulate the laminar flow field and the mixing time of highly viscous non-Newtonian fluid in stirred tank with double layer straight impeller. The flow field characteristics, the spreading process of tracer, the responding curves of tracer concentration and the mixing time are analyzed. The tracer particles and the acid-base indicator method are used to measure the flow field and the mixing process in a transparent plexiglass stirred tank in experiment. The results show that the tracer is flowing and diffusing with main medium first in the feeding half of stirred tank because of the intermediate surface between double paddle, then diffusing to the other half when the concentration difference has increased. The shorter mixing time is obtained when feeding tracer at the blade-closed-area which stirred vigorously or at the intermediate surface. Different time are used to complete mixing at different points, so choosing reasonable monitor points with mixing require could avoid resource wasting or insufficient stirring. The mixing process of the medium in stirred tank is faster and the mixing time is shorter when increasing stirring speed. The accuracy of the numerical simulation results is verified by the experimental results. The research provides the theory basis for the design and engineering application of the laminar flow stirred tank with non-Newtonian fluid.
