论文部分内容阅读
为了保证混流式水轮机运行安全,分析了尾水管内部的空化流场。假设气液混相均质,并考虑不可凝结气相,采用基于组份输运方程,求解了尾水管内气液混相均质流的雷诺平均N-S方程以及气相组分输运方程。结果表明:不同装置空化系数下尾水管压力脉动主频率变化不大,但在极低的装置空化系数下,削波现象导致更低频率成分的出现。在较大的装置空化系数下,空化涡带直径较小,压力脉动幅值随装置空化系数的变化不明显;当装置空化系数小于某一临界值后,随装置空化系数的降低,压力脉动幅值增加并达到一个最大值。计算结果解释了模型试验现象。
In order to ensure the running safety of the Francis turbine, the cavitation flow field inside the draft tube was analyzed. Assuming homogeneous gas-liquid mixing and taking into account the non-condensable gas phase, the Reynolds averaged N-S equation and the gas-phase component transport equation for the homogeneous gas / liquid flow in the draft tube were solved based on the component transport equation. The results show that the pressure fluctuation of the draft tube changes little with the cavitation coefficient of different devices. However, under the low device cavitation coefficient, the clipping phenomenon leads to the appearance of lower frequency components. Under the larger device cavitation coefficient, the diameter of cavitation vortex is smaller and the amplitude of pressure pulsation is not obvious with the change of device cavitation coefficient. When the device cavitation coefficient is less than a certain critical value, Decrease, increase the pressure pulsation amplitude and reach a maximum value. The calculation results explain the model test phenomenon.