【作者】 聂毅强；

【导师】 施力田； 包雨云；

【作者基本信息】 北京化工大学 ， 化学工程， 2001， 硕士

【摘要】 本文对简化的粒子成像测速技术(PIV)，利用AUTOCAD的二次开发工具简化了图像处理过程，节省了数据采集时间，提高了测量精确度，并适于处理清晰度较差的流场图像，使其适用于大尺寸、流质透明度较差的搅拌槽体系的流场测量。 PIV法能够测量同一时刻流场中某一平面上许多点的瞬时速度，保留了流场空间结构信息，适用于搅拌槽内强非定态流场的测量。而单点测量技术不会记录下瞬态流场的空间相关信息。 将改进的PIV技术应用于搅拌槽内质量分数为0.6％CMC水溶液和清水流动场的测量，比较了输入功率相同时CBY桨和PBT桨，在不同转速(两个转速)，不同桨层数(单、双层)在0.6％CMC水溶液和清水中的流场特性。清水中CBY桨和PBT桨以轴向流动为主，PBT桨有较大的径、切向速度；0.6％CMC水溶液中CBY桨和PBT桨切向流占优势，单层桨不能形成良好的轴向循环；增加转速有利于提高轴向流动；双层桨在桨间存在停滞流，不利于全流场轴向循环的形成，尤其以双层PBT桨在0.6％CMC水溶液流场最明显。 利用计算流体力学软件CFX对实验条件下的单层CBY桨和PBT桨在清水中，两种转速的流场和单层PBT桨在0.6％CMC水溶液的流场进行了模拟，并与实验结果进行了比较。数值模拟的流场图与实验流场图基本一致，不同位置轴向时均速度的模拟值与实验值吻合很好，但最大值偏大。径向、切向时均速度与实验值有一定的差别。更多还原

【Abstract】 A modified Particle Image Velocimetry (PIV) was developed in this work with simplified data acquisition and image processing system. The modified PIV could be used in the flow field measurement of big size tank and poor transparence fluid.Experiments were carried out in a baffled stirred tank of 0.5m diameter filled with 0.6 wt % CMC aqueous solution and water respectively. The flow fields generated by a 4-blade 45 pitched-blade turbine (PBT) and a 2-blade CBY at different rotational speeds were measured by using the modified PIV. Also the similar flow fields but generated by double 45?PBTs and double 2-blade CBYs were measured. All the comparable experiments were carried out at the same power input.The velocity fields were dominated by axial flow in water but by tangent and radial flow in 0.6% CMC aqueous solution. The more the rotational speed, the more apparent the trend of axial flow; There exist stagnant area between the two impellors, especially in the flow fields generated by double PBTs, which seriously hampered the axial flow.The flow fields at the same conditions with those of the experiments were numerically simulated by the CFD (Computational Fluid Dynamics) software-CFX. The simulation results approximately agreed with the experimental data, especially in the trend of the velocity curves. Generally, the simulation velocity curves were smoother than those of the experiments and showed greater values.更多还原