摘要
基于有限体积方法,采用标准k-ε湍流模型,应用ANSYS CFX软件对不同工况下低比转速离心泵进口处的三维湍流流场进行了数值模拟.通过在进口流场中设置大量监测点,采集速度变化数据,对回流发生和发展过程中进口处的回流旋涡形态和流场速度分布进行了分析.提出了采用有机玻璃进水管,利用注入的空气气泡作为示踪粒子的可视化试验方案.使用高速摄影仪拍摄气泡的运动轨迹,从而分析不同工况下进水管流场的速度分布.结果表明:模型泵回流发生的关键流量点为0.7Qd;回流发生后,随流量的减小,回流强度增大,回流旋涡的体积变大,旋涡中心向进水管内移动,堵塞部分流道;进口回流会同时在叶轮和进水管内造成与主流方向相反的轴向速度和预旋,随回流强度的增大,轴面回流速度、进水管内的预旋强度增大,预旋在进水管中的影响距离最远到达距叶轮进口10倍叶轮进口直径处;当离心泵关阀运行时,在进水管内将形成柱状涡带.
Based on the finite volume method, the 3D steady turbulent flow in a centrifugal pump was simulated under different conditions using the standard turbulence model, the velocity distribution of the reeirculation flow field and vortex morphology were analyzed. The flow field in the suction pipe was visualized using a Ploymethyl Methacrylate suction pipe, and the injected air bubbles were used as tracers. The flow patterns under different conditions were shot with a high speed camera. The results indicated that the capacity of the recirculation onset is 0.7 Qd· As the flow rate decreases,the reeireulation intensity and its axial velocity at the entrance to the impeller and in the suction pipe are increased. Meanwhile, the reeireulation vortex becomes so big that it partially blocks the flow passages. A strong pre-rotation is created; it can travel upstream along the suction pipe for a long distance even up to 10 times the impeller inlet diameter. At the shut-off condition, a rope vortex appears in the suction pipe.
出处
《排灌机械工程学报》
EI
2011年第6期461-465,共5页
Journal of Drainage and Irrigation Machinery Engineering
基金
国家杰出青年科学基金资助项目(50825902)
国家自然科学基金资助项目(50979034)
关键词
离心泵
进口回流
数值模拟
流场特性
示踪粒子
centrifugal pump
inlet recirculation
numerical simulation
flow characteristics
tracer particles
