In order to explore the transient characteristics of the large-scale vertical siphon axial flow pumping station during the start-up and exhaust process, numerical simulations were carried out on the start-up process of the axial flow pumping station under the two starting modes of pre-opening the vacuum breaking valve and keeping the vacuum breaking valve closed. The calculation results show that during the start-up phase of the unit, the flow separation phenomenon of the impeller channel of the pump device with the vacuum breaking valve closed is serious, the large-scale vortex in the guide vane blocks the flow channel, and the instantaneous impact on the blade surface is strong. The flow field of the pump device with the pre-opened vacuum breaking valve is significantly less affected by the instantaneous impact characteristics during pump startup. The range of the high-entropy production area in the impeller channel is reduced, and the duration of the high-entropy production area is significantly shortened. The instantaneous impact is weak. Under the two starting modes, the internal flow field of the pump device is similar in the evolutionary law. The unstable flow phenomenon of the pump device is most prominent in the weir flow stage. The maximum instantaneous impact on the blade surface also mainly occurs in the weir flow stage. A very small part of the remaining gas in the siphon formation stage is difficult to discharge and takes a long time. The external characteristic parameters of the pump device after exhausting and entering a stable operation state are in good agreement with the test results. Compared with the starting method in which the vacuum breaking valve is kept closed, the method of pre-opening the vacuum breaking valve reduces the maximum starting head by 20% and the exhaust time by 43%. Pre-opening the vacuum break valve to start effectively avoids the system instability caused by the pump device during the start-up and exhaust process.

中文翻译：

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大型立式虹吸轴流泵站启动过渡过程瞬态特性数值模拟

为探究大型立式虹吸轴流泵站在启动和排气过程中的瞬态特性，对轴流泵站在两种启动方式下的启动过程进行了数值模拟。预先打开真空破坏阀并保持真空破坏阀关闭。计算结果表明，在机组启动阶段，真空破坏阀关闭的泵装置叶轮通道分流现象严重，导叶内大范围涡流堵塞流道，对叶片表面的瞬时冲击力强。预开真空破坏阀的泵装置流场受泵启动时瞬时冲击特性的影响明显较小。叶轮通道内高熵产区范围缩小，高熵产区持续时间显着缩短。瞬间冲击力微弱。两种启动方式下，泵装置内部流场演化规律相似。泵装置的不稳定流动现象在堰流阶段最为突出。对叶片表面的最大瞬时冲击也主要发生在堰流阶段。虹吸形成阶段的残留气体极少部分难以排出，耗时较长。泵装置排气进入稳定运行状态后的外特性参数与试验结果吻合较好。与真空破坏阀保持关闭的启动方式相比，真空破坏阀预开启的方式最大启动扬程降低20%，排气时间减少43%。预开真空破坏阀启动有效避免了泵装置在启动和排气过程中造成的系统不稳定。