竖井式进/出水口数值模拟策略研究

数值模拟在抽水蓄能电站进/出水口水力设计中的应用日趋广泛，但网格尺度的差异和不同湍流模型的选用均会对数值模拟结果产生影响。为准确、定量地评估二者的影响，本文以西龙池抽水蓄能电站竖井式进/出水口为例，针对3种网格尺度，采用4种常用湍流模型，在进流和出流工况下，对比分析了网格尺度对水头损失系数、流速不均匀系数等水力指标的影响。选用网格收敛指数定量评价各湍流模型在3种网格尺度的数值模拟误差，用以确定合理的网格尺度，在此基础上分析4种湍流模型的适用性。结果表明，在3种网格尺度下各湍流模型的计算结果均处于解析解的渐近域内，且当孔口网格由0.05D加密至0.03D时，数值模拟误差降低最明显。Realizable 模型对进流和出流工况的水力指标预测均较准确，与试验值的相对误差均达到5%。研究成果可为进一步提高进/出水口计算精度提供参考。

Study on numerical simulation strategy of vertical pipe intake/outlet

Numerical simulation is widely used in hydraulic design of the intake/outlet of pumped storage power stations, but its accuracy varies with the differences in mesh resolutions and turbulence models adopted. This paper evaluates these two types of errors by comparing three mesh scales and four commonly-used turbulence models through numerical simulations of the vertical intake/outlet flows at the Xilongchi hydropower station. And influence of mesh accuracy on head loss coefficient and velocity non-uniformity coefficient, among other hydraulic indexes, is analyzed for the inflow and outflow working modes of the intake/outlet. We use a grid convergence index to estimate the errors of the four turbulence models on different mesh scales and determine which scale is optimal, and examine their applicability to calculations of the two coefficients and orifice velocity distribution. The results show that all the four models on the three mesh scales satisfy convergence criteria, and mesh accuracy improves most significantly when the orifice grid size is refined from 0.05D to 0.03D. Because the results at 0.03D are close to converged solutions, further refinement has little effect on computational accuracy. Realizable is shown to be more accurate in predicting the hydraulic indexes of flows in both working modes, with prediction errors of about 5%. The results help improve accuracy in CFD calculations of vertical pipe intakes/outlets.