泥沙浓度对水力机械材料磨损及磨蚀特性的影响

Influence of sediment concentration on abrasion and erosion characteristics of hydraulic machinery materials

多泥沙河流上运行的水力机械受到泥沙磨蚀而导致过流部件变形、破坏,严重威胁机组安全运行。本研究对水力机械常用材料开展了旋转喷射磨蚀试验,采用失重法和微观形貌分析法研究了泥沙浓度对材料磨损及磨蚀特性的影响。结果表明:材料受到冲击磨损和磨蚀的累积失重量均随泥沙浓度变化呈近线性增长;当泥沙浓度小于60 kg/m^(3)时,3种材料累积失重量随泥沙浓度增长较缓;当泥沙浓度大于60 kg/m^(3)时,材料失重量增长较快。随着泥沙浓度的增大,冲击磨蚀对材料造成更严重的破坏,但空蚀损伤呈减弱趋势,材料表面硬度越高,抗空蚀性能越好,磨损和磨蚀失重量相等的临界泥沙浓度越低。空蚀作用会影响沙粒撞击材料表面的角度,导致颗粒水平冲击载荷更大,磨痕呈现切削唇边和堆积,在更高泥沙浓度下沙粒切削破坏占据主导作用。

Hydraulic machineries running on muddy rivers suffer from sediment erosion that often causes deformation and damage to flow components,seriously threatening the safe operation of hydropower plants.This study conducts an experiment on a rotating jet facility to examine the influence of sediment concentration on the impact abrasion and erosion characteristics of hydraulic machinery materials,using the weight loss method and Scanning Electron Miscroscopy(SEM).The results show the cumulative weight loss of materials from impact abrasion and erosion takes a nearly linear increase with the rise of sediment concentration.With sediment concentration lower than 60 kg/m^(3),the increase in the cumulative weight loss of the tested three material is gradual;it becomes rapid at higher concentration.As the concentration increases,the impact erosion causes more severe damage to the materials,but cavitation erosion shows a weakening trend.The higher the surface hardness of the material,the better its resistance to cavitation erosion,and the lower the critical sediment concentration at which the weights of abrasion and erosion are equal.Flow cavitation affects the angle at which sand particles impact on the material surface,and it usually increases the horizontal impact load of the particles.The abrasion marks show lip edges and material accumulation,and the sand particle cutting damage dominates at higher sediment concentrations.