The axial profile of gas holdups was measured using a γ-ray densitometry in the pressurized bubble column,0.3 m in diameter and 6.6 m in height.The principle of γ-ray measurement and data processing is discussed.The...The axial profile of gas holdups was measured using a γ-ray densitometry in the pressurized bubble column,0.3 m in diameter and 6.6 m in height.The principle of γ-ray measurement and data processing is discussed.The axial profile of gas holdups and its average value in two-phase system were obtained in the churn-turbulent flow regime with a gas velocity up to 0.40 m·s -1 and a system pressure up to 1.0 MPa, which are in agreement with results obtained by differential pressure method.The effects of superficial gas velocity, liquid surface tension, liquid viscosity and system pressure on the axial profile of gas holdups were investigated.It is shown that the gas holdup decreases with the increasing liquid viscosity and liquid surface tension, and increases with the increase of pressure and superficial gas velocity.展开更多
在内径160 mm,高300 mm 的玻璃槽中,采用0～200 W 可调功聚能型超声波发生器研究了超声波功率、聚能头与进气管距离、聚能头放置方式、聚能头投入深度、进气流量和反射室直径等因素对气液鼓泡流中气泡发生频率的影响。实验结果表明,聚...在内径160 mm,高300 mm 的玻璃槽中,采用0～200 W 可调功聚能型超声波发生器研究了超声波功率、聚能头与进气管距离、聚能头放置方式、聚能头投入深度、进气流量和反射室直径等因素对气液鼓泡流中气泡发生频率的影响。实验结果表明,聚能头竖直放置时,随着功率的增加,单位时间内气泡数目先减少而后急剧增加;聚能头水平放置时,单位时间内气泡数目随着功率增加而增加;聚能头距分布管越远,超声波对气泡的破碎作用越小,气体流量越大,单位时间内气泡数目越多,反射室直径在一定范围内越小,单位时间内气泡数目越多。展开更多
A full second-order moment (FSM) model and an algebraic stress (ASM) two-phase turbulence modelare proposed and applied to predict turbulent bubble-liquid flows in a 2D rectangular bubble column. Predictiongives the b...A full second-order moment (FSM) model and an algebraic stress (ASM) two-phase turbulence modelare proposed and applied to predict turbulent bubble-liquid flows in a 2D rectangular bubble column. Predictiongives the bubble and liquid velocities, bubble volume fraction, bubble and liquid Reynolds stresses and bubble-liquidvelocity correlation. For predicted two-phase velocities and bubble volume fraction there is only slight differencebetween these two models, and the simulation results using both two models are in good agreement with the particleimage velocimetry (PIV) measurements. Although the predicted two-phase Reynolds stresses using the FSM are insomewhat better agreement with the PIV measurements than those predicted using the ASM, the Reynolds stressespredicted using both two models are in general agreement with the experiments. Therefore, it is suggested to usethe ASM two-phase turbulence model in engineering application for saving the computation time.展开更多
文摘The axial profile of gas holdups was measured using a γ-ray densitometry in the pressurized bubble column,0.3 m in diameter and 6.6 m in height.The principle of γ-ray measurement and data processing is discussed.The axial profile of gas holdups and its average value in two-phase system were obtained in the churn-turbulent flow regime with a gas velocity up to 0.40 m·s -1 and a system pressure up to 1.0 MPa, which are in agreement with results obtained by differential pressure method.The effects of superficial gas velocity, liquid surface tension, liquid viscosity and system pressure on the axial profile of gas holdups were investigated.It is shown that the gas holdup decreases with the increasing liquid viscosity and liquid surface tension, and increases with the increase of pressure and superficial gas velocity.
文摘在内径160 mm,高300 mm 的玻璃槽中,采用0～200 W 可调功聚能型超声波发生器研究了超声波功率、聚能头与进气管距离、聚能头放置方式、聚能头投入深度、进气流量和反射室直径等因素对气液鼓泡流中气泡发生频率的影响。实验结果表明,聚能头竖直放置时,随着功率的增加,单位时间内气泡数目先减少而后急剧增加;聚能头水平放置时,单位时间内气泡数目随着功率增加而增加;聚能头距分布管越远,超声波对气泡的破碎作用越小,气体流量越大,单位时间内气泡数目越多,反射室直径在一定范围内越小,单位时间内气泡数目越多。
基金Supported by the Special Funds for Major State Basic Research Projects, PRC(G1999-0222-08) and the National Natural Science Foundation of China(No. 19872039).
文摘A full second-order moment (FSM) model and an algebraic stress (ASM) two-phase turbulence modelare proposed and applied to predict turbulent bubble-liquid flows in a 2D rectangular bubble column. Predictiongives the bubble and liquid velocities, bubble volume fraction, bubble and liquid Reynolds stresses and bubble-liquidvelocity correlation. For predicted two-phase velocities and bubble volume fraction there is only slight differencebetween these two models, and the simulation results using both two models are in good agreement with the particleimage velocimetry (PIV) measurements. Although the predicted two-phase Reynolds stresses using the FSM are insomewhat better agreement with the PIV measurements than those predicted using the ASM, the Reynolds stressespredicted using both two models are in general agreement with the experiments. Therefore, it is suggested to usethe ASM two-phase turbulence model in engineering application for saving the computation time.
