Abstract: The flow characteristics in a stirred vessel of diameter (T) 0.476 m agitated by double narrow blade hydrofoil CBY impellers were experimentally investigated by using particle image velocimetry (PIV). The effects of the spacing between the two impellers (H2), the submergence of the upper impeller below the liquid surface (H3), and the clearance of the lower impeller above the base of the vessel (H1) on the flow pattern were investigated. The PIV results show that when H2 is not more than 0.6T, a whole axial circulation forms in the vessel, when H2 is not less than 0.7T, the circulation is separated into two smaller ones. The submergence (H3) has little effect on the velocity near the impeller region. With decreasing of H1, the radial flow generated by the lower impeller, the axial flow generated by the upper impeller, and the axial flow of the main circulation increase.

Key words: double hydrofoil impeller, flow field, particle image velocimetry, stirred vessel

摘要： 在直径0.476 m的搅拌槽内，采用粒子图像测速技术对双层三叶CBY翼型桨搅拌槽内的流场进行了研究，考察了层间距、浸没深度和离底高度等参数对流场分布的影响. 结果表明，层间距H2≤0.6T(T为搅拌槽直径)时，槽内可形成整体的轴向循环流动，H2≥0.7T时槽内将产生分区流动现象. 浸没深度对桨叶排出流区域的速度影响很小. 降低下层桨的离底高度能加强下层桨的径向流动，并增大上层桨叶轮区和循环区流体的轴向流动.

关键词: 双层翼型桨, 流场, 粒子图像测速技术, 搅拌槽