磨损模型对固液两相流泥沙磨损计算影响

Influence of erosion models on calculations of sediment erosion in solid-liquid two-phase flows

黄河沿岸水流含有大量悬移质泥沙颗粒,极易对水轮机过流部件造成泥沙磨损。选择合适的磨损模型计算磨损深度具有重要意义。本研究采用四种磨损模型,在两种颗粒直径和两种流速条件下,对直角弯管固液两相流场进行数值模拟。通过对比计算所得的磨损深度与实验值,筛选出适用于黄河沿岸悬移质颗粒的磨损模型。结果表明:磨损区域主要位于上下游管道连接位置及下游圆周向90°、270°位置,大颗粒直径90°~270°磨损更加明显;综合来看,Tusla和Oka模型计算精度更高。大颗粒直径推荐使用Oka模型进行计算,其在兼顾计算精度的前提下,又因其模型中考虑了颗粒直径;小颗粒直径条件,推荐使用计算精度最高的Tusla模型来计算小颗粒磨损问题。本研究可为黄河沿岸水电站的固相两相流泥沙磨损计算提供模型选择参考。

The Yellow River carries huge amount of suspended particles,which would cause sediment erosion on flowing components of hydraulic turbines.The selection of a proper erosion model is crucial for the accurate numerical prediction of the erosion depth.In this study,four erosion models are applied respectively to numerically simulate the solid-liquid two-phase flow in a right-angle bend under the conditions of two particle diameters and two flow velocities.By comparing the predicted erosion depth with previous experimental data in literature,we screen out suitable erosion models for the numerical simulation of erosion caused by suspended sediments from the Yellow River.The results show the erosion zones are concentrated on the connecting sections of the upstream and downstream turbine pipelines and the downstream circumferential locations of 90°and 270°,and erosion caused by large particles can also be observed in the range of 90°-270°.In general,both the Tusla model and Oka model could perform better accuracy.The Oka model is recommend for simulations with larger sediment particles,which is equipped with the factor of sediment particle diameter and is superior in accuracy.The Tusla model,yielding the highest accuracy,has better performance in small sediment particle conditions.Oriented to the hydropower stations in the Yellow River basin,this study suggests the selection of proper numerical model for sediment erosion simulation.