化工进展
化工進展
화공진전
CHEMICAL INDUSTRY AND ENGINEERING PROGRESS
2013年
11期
2569-2573,2578
,共6页
湍流模型%气液搅拌槽%气泡尺寸分布%局部气含率%计算流体力学%群体平衡模型
湍流模型%氣液攪拌槽%氣泡呎吋分佈%跼部氣含率%計算流體力學%群體平衡模型
단류모형%기액교반조%기포척촌분포%국부기함솔%계산류체역학%군체평형모형
turbulent models%gas-liquid stirred tank%bubble size distribution%local gas holdup%computational fluid dynamics(CFD)%population balance model
采用计算流体力学（CFD）方法，应用Euler-Euler双流体模型，桨叶采用多重参考系法（MFR），与考虑气泡聚并与破碎对气泡尺寸影响的群体平衡模型（PBM）相结合，比较了标准k-ε、Realizable k-ε和RNG k-ε3种湍流模型对双层涡轮搅拌釜内气-液两相液相流场、局部气含率及气泡尺寸分布的影响。结果表明：3种湍流模型预测的液相流场流型相似，总体气含率预测值相差不大，均与实验值吻合较好。对于局部气含率，标准k-ε和RNG k-ε模型在桨叶区的预测值偏大，在接近自由液面处三者预测值均偏低，Realizable k-ε模型预测结果与实验值符合最好；对于气泡尺寸，3种湍流模型预测结果均与实验值较吻合，在靠近自由液面处预测值均偏小，气泡尺寸分布与湍流长度分布相吻合。
採用計算流體力學（CFD）方法，應用Euler-Euler雙流體模型，槳葉採用多重參攷繫法（MFR），與攷慮氣泡聚併與破碎對氣泡呎吋影響的群體平衡模型（PBM）相結閤，比較瞭標準k-ε、Realizable k-ε和RNG k-ε3種湍流模型對雙層渦輪攪拌釜內氣-液兩相液相流場、跼部氣含率及氣泡呎吋分佈的影響。結果錶明：3種湍流模型預測的液相流場流型相似，總體氣含率預測值相差不大，均與實驗值吻閤較好。對于跼部氣含率，標準k-ε和RNG k-ε模型在槳葉區的預測值偏大，在接近自由液麵處三者預測值均偏低，Realizable k-ε模型預測結果與實驗值符閤最好；對于氣泡呎吋，3種湍流模型預測結果均與實驗值較吻閤，在靠近自由液麵處預測值均偏小，氣泡呎吋分佈與湍流長度分佈相吻閤。
채용계산류체역학（CFD）방법，응용Euler-Euler쌍류체모형，장협채용다중삼고계법（MFR），여고필기포취병여파쇄대기포척촌영향적군체평형모형（PBM）상결합，비교료표준k-ε、Realizable k-ε화RNG k-ε3충단류모형대쌍층와륜교반부내기-액량상액상류장、국부기함솔급기포척촌분포적영향。결과표명：3충단류모형예측적액상류장류형상사，총체기함솔예측치상차불대，균여실험치문합교호。대우국부기함솔，표준k-ε화RNG k-ε모형재장협구적예측치편대，재접근자유액면처삼자예측치균편저，Realizable k-ε모형예측결과여실험치부합최호；대우기포척촌，3충단류모형예측결과균여실험치교문합，재고근자유액면처예측치균편소，기포척촌분포여단류장도분포상문합。
This paper investigated the simulation of liquid velocity, local gas holdup and bubble size in a stirred tank with dual turbine impellers using computational fluid dynamics(CFD). The results from three different turbulence models (Standard k-ε,RNG k-ε,Realizable k-ε) were compared. The Euler-Euler multiphase flow model and multiple frames of reference(MFR) method were used in the simulations. A population balance model(PBM) was implemented in order to account for the combined effect of bubble break-up and coalescence in the tank. The results showed that the flow patterns of liquid phase and the total gas holdups predicted by the three models had no significant difference, and the total gas holdups agreed well with the experimental data. The standard k-ε and RNG k-ε models over predicted the local gas holdup values at the impeller regions, and in the upper part of the vessel near the liquid-free surface where the local gas holdups predicted all were lower than the measurements. The realizable k-ε model gave the best result compared with the experimental data. The simulated results and experimental data agreed well at most of the points in the tank except for the part near the liquid-free face for the bubble sizes. The bubble size distribution was consistent with the turbulence length distribution.
