基于 FBM 模型的轴流泵空化流动特性 CFD 分析

轴流泵运行工况多变,容易发生空化,会严重影响泵的水力性能。为研究轴流泵空化工况下的流动特性,进行了全流道空化流动数值模拟和压力脉动分析,通过比较实验数据和不同湍流模型的计算结果,验证了FBM模型在预测轴流泵外特性和空化性能方面的优越性。研究结果表明:FBM模型预测非设计条件下的数值误差最小,特别是在具有小流量条件的流场中误差最小,其中平均扬程误差1.19%,平均效率误差5.31%;FBM在预测空泡体积数、含气量上的精度均大于其他三种湍流模型,与实验结果最接近;在NPSH=5.25m空化刚开始阶段,叶片上的压力脉动的主要频率位于fn及其倍频处,叶片吸力面的压力监测点由于受到空泡溃灭影响出现大量低频幅值,导叶出口监测点的压力脉动受到导叶片背面流动状态的影响出现大量低频信息。

CFD analysis of cavitation flow for axial2flow pump based on FBM model

The w orking co ndit ion of the ax ial f low pump is changeable, and cavitat ion is easy t o occur, w hich can seriously affect the hy dr aulic performance of a pump. T o study the flow characteristics o f the ax ial flow pump under cavitat ion co ndition, nu2 merical simulatio ns and pr essure pulsatio n analysis o f cavitat ion flow in full channel w ere carried o ut. The superiority of FBM model in predicting the ex ter nal characteristics and cavitation performance of axial flow pump w as v erified by comparing the ex2 perimental data based o n calculated r esults o f different turbulence models. The results showed that the FBM model had least er2 r or in pr edict ing ex ternal char acteristics under non2desig n conditio ns, especially in the flow field under small flow conditio ns. The averag e lift err or w as 11 19% , and the aver age efficiency err or w as 51 31% , respectively . T he accur acy of FBM in predicting cav itation vo lume and g as fr actionw as hig her than o ther thr ee turbulence models, w hich w as mostly close to the obtained ex peri2 mental r esults. In the initial stage of NPSH = 51 25 m cavitat ion, the main f requency o f pr essure pulsat ion on the blade w as loca2 ted at f n, and its frequency w as do ubled, while la rge number of low2fr equency amplitudes appear ed at the pressur e monitoring po int on the suction surface of the blade due to the influence of cav itation collapse. The pr essure pulsatio n at the outlet of the guide vane w as influenced by the flow pattern on the back of the g uide blade.