Energy Balance and Local Unsteady Loss Analysis of Flows in a Low Specific Speed Model Pump-Turbine in the Positive Slope Region on the Pump Performance Curve
Energy Balance and Local Unsteady Loss Analysis of Flows in a Low Specific Speed Model Pump-Turbine in the Positive Slope Region on the Pump Performance Curve
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低比转速模型水泵水轮机泵性能曲线正斜率区域流动的能量平衡和局部非定常损失分析
DOI：
10.3390/en12101829
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发表时间：
2019-05
期刊：
影响因子：
3.2
通讯作者：
Shuhong Liu
中科院分区：
文献类型：
--
作者：
Guocheng Lu;Zhigang Zuo;Demin Liu;Shuhong Liu
水泵水轮机水泵性能曲线上的正斜率表明水泵模式下存在潜在的运行不稳定性。以往的研究表明，水泵水轮机内流态突变引起的水力损失增加是导致正斜率的原因，但其详细的流动机理尚不清楚。采用v2-f湍流模型，对低比转速水泵水轮机模型进行了非定常RANS数值模拟。从能量平衡的角度讨论了泵性能曲线上出现正斜率的机理，即当Pu_Q大于临界值Pu_Q时，泵性能曲线上出现正斜率区域。从能量方程出发，进行了非定常局部损失分析，以说明局部流型对相应液压元件损失的贡献。首次考虑了平均流动能的变化，使得该方法可以应用于高度时间依赖的流型，例如，在本研究中的旋转失速。流态的研究表明，一些导叶通道失速，流量系数大于正斜率区域。失速通道附近的几个导叶通道失速，流量系数略有下降，导致输入功率和损失突然增加。流量系数进一步减小时，水泵水轮机进入正斜率区，出现3个失速单元的旋转失速，压力脉动的快速傅里叶变换和交叉相位分析证实了这一点。
The positive slope on the pump performance curve of pump-turbines suggests potential operational instabilities in pump mode. Previous research has indicated that the increase of the hydraulic loss caused by sudden changes of flow patterns in pump-turbines is responsible for the positive slope, however its detailed flow mechanism is still unclear. A low specific speed model pump-turbine was numerically investigated against experiments in the present study, by applying unsteady RANS (Reynolds-Averaged Navier–Stokes equations) simulations with a v2-f turbulence model. The mechanism of occurrence of the positive slope on the pump performance curve was discussed regarding the energy balance, as this region appears when the value of ∂ P u ∂ Q is larger than the critical value P u Q . An unsteady local loss analysis, derived from the energy equation, was conducted to illustrate the contribution of local flow patterns to the loss in corresponding hydraulic components. The variation of the kinetic energy of the mean flow was taken into account for the first time so that this method can be applied to highly time dependent flow patterns, e.g., a rotating stall in the present study. The investigations on the flow patterns revealed that some guide vane channels stalled with a larger discharge coefficient than the positive slope region. Several guide vane channels near the stalled channels were stalling with minor decrease of the discharge coefficient, leading to sudden increases of the input power and the loss. When the discharge coefficient slightly decreased in further, the pump-turbine operated into the positive slope region, and the rotating stall with 3 stall cells appeared, proven by the FFT (Fast Fourier Transform) and cross-phase analysis on the pressure fluctuations.
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DOI：
10.1007/s10494-016-9767-9
发表时间：
2016-09
期刊：
Flow, Turbulence and Combustion
影响因子：
--
作者：
S. Wilhelm;G. Balarac;O. Métais;C. Ségoufin
通讯作者：
S. Wilhelm;G. Balarac;O. Métais;C. Ségoufin
DOI：
10.5075/epfl-thesis-5373
发表时间：
2011
期刊：
--
影响因子：
--
作者：
V. Hasmatuchi;M. Farhat;S. Roth;F. Botero;F. Avellan
通讯作者：
V. Hasmatuchi;M. Farhat;S. Roth;F. Botero;F. Avellan
影响因子：
2.4
作者：
J. Paik;F. Sotiropoulos;M. Salé
通讯作者：
J. Paik;F. Sotiropoulos;M. Salé
DOI：
10.5075/epfl-thesis-4422
发表时间：
2009
期刊：
--
影响因子：
--
作者：
O. Braun
通讯作者：
O. Braun
空化对低比转速模型水泵水轮机泵性能曲线正斜率影响的实验证据
影响因子：
8.7
作者：
Guocheng Lu;Zhigang Zuo;Yuekun Sun;Demin Liu;Yoshinobu Tsujimoto;Shuhong Liu
通讯作者：
Shuhong Liu