基于动态边界的90°弯管壁面渐进磨损特性

Progressive erosion of 90°elbow wall based on dynamic boundary

固定边界磨损预测方法只能得到磨损初始边界状态下的磨损特性,无法获得壁面破坏后的流场动力学响应.由此,基于计算流体力学提出动态边界的水力机械过流壁面渐进磨损数值预测方法,通过研究90°弯管在不同磨损时刻的磨损表面形貌,流场特性、磨损特性和颗粒冲击特性,揭示由于过流壁面磨损形貌演变引起的多相流特性和磨损演变机理.研究结果表明:在来流速度6.3 m/s、颗粒体积分数为0.35%的90°弯管中,磨损主要集中在末端(50°~90°)内壁附近,且在20000 h以后,外侧内壁的平均磨损率与内侧之比增大到2倍附近;颗粒冲击速度呈现先增加后减小的规律,最大变化量为0.81 m/s,而颗粒冲击角度呈现近乎线性增加,平均最大增幅为1.13°;此外,磨损坑内颗粒冲击速度减小,磨损坑边缘冲击速度增加,说明随着磨损时间的增加磨损范围会进一步扩大,研究结果为弯管的磨损防护提供了一定的参考.

The fixed boundary wear prediction method can only obtain the wear characteristics under the initial boundary state of wear,and cannot obtain the dynamic response of the flow field after wall failure.A method for predicting the progressive erosion of the sandy water flow-passage walls with dynamic boundary was proposed based on Computational Fluid Dynamics(CFD).The wall erosion morphology as well as the characteristics of flow field,erosion and particle impact of the 90°elbow at different erosion times were studied.the multiphase flow characteristics and wear evolution mechanism caused by the evolution of the wear morphology of the flow passage wall were revealed.The results show that in a 90°elbow with an inflow velocity of 6.3 m/s and the particle volume fraction of 0.35%,the erosion is mainly concentrated near the end(50°-90°)of the inner wall.And after 20000 hours,the average erosion rate of the outer inner wall and inner wall is increased to about 2 times.The distribution of particle impact velocity shows a law of increasing first and then decreasing,and the maximum changes is 0.81 m/s.While the particle impact angle increases almost linearly,with an average maximum increase of 1.13°.Moreover,the impact velocity of particles in the erosion pits decreases,while the impact velocity at the edge of the erosion pit increases,indicating that the erosion range will further expand with the increase of erosion time.The research results provide a reference for the erosion protection of elbows.