低比转速高速离心泵内部流场分析-流体机械及工程专业论文.docxVIP

西安理 西安理工大学硕士学位论文 II Ⅰ Ⅰ II II Abstract Title: Research and Analysis of Internal Flow Field for Low Specific Speed and High Speed Centrifugal Pump? Major：Fluid Machinery and Engineering Name: Lianming Zhao Signature: Supervisor: Prof. Xingqi Luo Signature: Supervisor: Assoc. Prof. Jinling Lu Signature: Abstract The centrifugal pump with low specific speed is characterred with small outlet blade width, large impeller diameter and the narrow passage, this pump probably has large disk friction loss and easy to appear jet-wake, hump phenomenon in the H-Q curve. Moreover the centrifugal pump at high-capacity operating condition is easy to overload. Therefore, the low specific speed centrifugal pump has been a hotspot and difficulty of research scholars at home and abroad. Intense researches have been conducted by many scholars in the geometric parameter optimization design, experimental study and numerical simulation. In this paper a chemical low specific speed centrifugal pump is calculated applying numerical simulation method to analyze the flow condition. The result shows a hump to the H-Q charac- teristic curve, jet wake at the impeller outlet and the N-Q curve appears a rising trend. In order to solve the above problems, this paper applied tandem blade technology, which is widely used in the steam turbine impeller and centrifugal fan, to research internal and external performance of centrifugal pumps with different design options. Firstly, the pump blades are cut and rotated circumferentially. Then we selected the better parameter matches of the tandem blades, under which the pump turns better performs. Meanwhile, the pressure fluctuation is analyzed with two types of impellers: the original pump and the changed one. Research results show that, flow filed in the impeller is more smooth when the circumferential angle θ 0 °, with the jet flow at export between the tandem cascade improving; a large flow separation phenomenon appears on the suction surface o