带叶片扩压器离心压缩机模型级内流研究

Internal Flow at Developed Model Stage in Centrifugal Compressor with Vaned Diffuser

通过对在研工业用带翼型叶片扩压器离心压缩机模型级的内部流动进行数值模拟,以及对模型级外特性进行了实验研究,分析了模型级内部流动特点、损失机理及其对级性能的影响。研究发现:该离心压缩机模型级性能较好,工况范围内效率曲线非常平坦,稳定运行范围较宽,整级效率高达82%;设计流量下叶轮出口轮盖与叶片吸力面的角区有明显的尾迹区存在,小流量下进入叶片扩压器内的气流在叶腹的流动没有得到有效滞止,大流量下气流以冲击叶片扩压器叶腹为主,同时在叶背上出现了较大的旋涡区;不同工况下叶片扩压器内的流动损失和扩压效果由不同工况下的流动特性决定。数值模拟和实验研究获得的模型级外特性曲线一致,表明所采用的数值模型能够准确预测模型级内部的流动特性。

The internal flow at model stage in centrifugal compressor with 3D centrifugal impeller and vaned diffuser is investigated by numerical simulation, the external performance at model stage is determined by experiments. The internal flow at model stage and the total pressure loss, as well as their influences on the stage performance, are analyzed. The results show that the centrifugal compressor at the model stage well performs with a very flat efficiency curve and the average efficiency gets as high as 82%. However, a wake region can be obviously observed at the outlet of the impeller near the shroud and the suction surface of the impeller when it runs under design flow rate condition. When the flow rate is greatly lower than the design level, the flow region near the pressure surface of the diffuser vane cannot keep effectively stagnant, leading to an extra loss of energy. When the flow rate is greatly higher than the design level, the airflow notably impinges on the pressure surface of the diffuser vane, and a large vortex region generates near the suction surface of the diffuser vane. The vaned diffuser performance depends upon the internal flow conditions during different operations. The predicted performance curve at this stage coincides well with that obtained by experiments.