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首页> 外文期刊>Proceedings of the Institution of Mechanical Engineers >Investigations of the unstable Q-H hump characteristic of a nuclear main pump
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Investigations of the unstable Q-H hump characteristic of a nuclear main pump

机译：核电主泵不稳定Q-H驼峰特性的研究

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摘要

As an important component of the nuclear power plant, nuclear main pump has high requirement in terms of the operational stability. An important stability problem of the nuclear main pump unit is the unstable flow-rate-head ( Q-H ) hump characteristic, which is a nonmonotonic pump head variation within a specific flow rate range. To understand the unstable Q-H hump characteristic in the nuclear main pump, an engineering case is investigated in this study based on the computational fluid dynamics simulation and experiment in the cold state. In this case, the unstable Q-H hump region is found in a wide design flow rate range from 0.4 to 0.7. According to the hydraulic loss analysis, the Q-H hump is found to be relative to the increase in the hydraulic loss in the stators. When the flow rate decreases below 0.7 design flow rate, vortices occur in the suction chamber. The backflow structure is found near the impeller inlet. Large-scale vortices are also found in the guide vane passage and volute. These undesirable flow structures affect the flow regime, block the flow passage, and cause the increase in the hydraulic loss in all the stators. As a result of the superposition of high hydraulic loss, the increase in the impeller head is strongly counterbalanced. The pump head drops and forms the unstable Q-H hump characteristic. This study reveals the mechanism of the unstable Q-H hump characteristic in the nuclear main pump. The results provide a reference for the no-hump design and operation of the nuclear main pump unit.
机译：作为核电站的重要组成部分，核主泵在运行稳定性方面有很高的要求。核主泵单元的重要稳定性问题是不稳定的流量扬程（Q-H）驼峰特性，这是特定流量范围内的非单调泵头变化。为了了解核主泵中不稳定的Q-H驼峰特性，基于计算流体动力学仿真和冷态实验，研究了一个工程案例。在这种情况下，在0.4至0.7的宽设计流量范围内发现了不稳定的Q-H峰区域。根据水力损失分析，发现Q-H峰与定子中水力损失的增加有关。当流量降低到0.7设计流量以下时，吸气室内会产生涡流。在叶轮入口附近发现回流结构。在导向叶片通道和蜗壳中也发现了大型涡旋。这些不希望的流动结构影响流动状态，阻塞流动通道，并导致所有定子中的水力损失增加。由于高水力损失的叠加，大大抵消了叶轮头的增加。泵压头下降并形成不稳定的Q-H驼峰特性。这项研究揭示了核主泵中不稳定的Q-H驼峰特性的机理。研究结果为核主泵机组的无驼峰设计和运行提供了参考。

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