开发高水头水电资源，尤其是我国西南地区的水电资源，面临的一个重要挑战是机组的泥沙磨损问题。由于运行水头高、高效区宽、易磨损部件少且维修难度低，冲击式水轮机有潜力在我国西南水电资源的开发中发挥重要作用。但当前对冲击式水轮机过流部件磨损特性的理解仍不够深入，主要的挑战在于其内部包含瞬态的水气两相流动，泥沙颗粒在这种多相流动中的运动特性极为复杂。在此背景下，本文以冲击式机组为研究对象，提出了其内部挟沙流动计算的新方法，发展了过流部件的磨损预估方法，并对机组内部泥沙颗粒的动力学特性以及过流部件的磨损特性展开了系统的研究。本文首先基于电站实测的过机泥沙物性参数，采用欧拉-拉格朗日（E-L）方法处理了水气沙三相流动的模拟问题，并基于Mansouri模型建立了磨损的预测方法。根据建立的数值计算方法，对两种不同结构形式的喷射机构进行了研究，分析了喷针开度、泥沙粒径的影响。数值模拟首次从物理上预测出了内控式喷射机构喷针表面非均匀的磨损现象，与电站观测现象一致，计算结果揭示了导流板下游喷针磨损加剧的原因是卡门涡街诱发的二次流。其次，根据E-L方法发展了挟沙流动计算方法并首次应用在旋转水斗内部非定常的水气沙三相流动中。在该方法中，提出了一种新的“冲击-反弹”模型用以预测颗粒撞击旋转壁面后的运动轨迹，并通过理论模型进行了验证。基于建立的新方法，探讨了不同开度、不同粒径下水斗内部泥沙颗粒的分布特性和聚集特性，发现颗粒有从流线分离的趋势，而这种趋势会受到颗粒所处位置、局部曲率半径、以及水膜流速的影响。进而，基于上述方法发展了累积磨损的预测方法，并成功应用于旋转水斗的磨损预测中。该方法修正了由于水斗壁面旋转导致的颗粒冲击特性变化，然后基于修正值获取了不同时刻的磨损特性，进而得到整个流动过程中的累积磨损。对不同开度、不同粒径下旋转水斗磨损特性的演变进行分析，并通过现场观测结果对计算方法进行验证。结果表明，缺口和分水刃附近曲面上的水膜起到了一定的保护作用：这些水膜阻止射流内颗粒直接冲击壁面，一定程度上降低局部的磨损速率。本文的研究揭示了冲击式水轮机内部挟沙流动特性以及磨损的形成机理，可以为冲击式水轮机的减磨优化设计提供一定的参考。

A major challenge in the development of high-head hydropower resources, especially those in southwest of China, is the hydro-abrasive erosion of turbine components. Due to the high operating head, wide high-efficiency zone, few flow components, and low maintenance difficulty, the Pelton turbine has the potential to play an important role in the development of hydropower in the southwest of China. However, the sediment-laden flow and erosion characteristics of Pelton turbines are still not deeply investigated. The main challenges are attributed to the transient air-water two-phase flow inside Pelton turbines, which makes the dynamics of sediment particles extremely complicated. In this paper, by using the Pelton turbine as the research object, a new method of simulating the sediment-laden flow and the erosion characteristics is developed for Pelton turbines. Based on the established approach, the particle dynamics and the erosion characteristics for the Pelton turbine have been systematically investigated. By using the sediment properties measured in field conditions, a numerical approach based on Euler-Lagrangian (E-L) method is developed to simulate the three-phase flow consisting of water, air, and sediments. Thereafter, Mansouri’s model is adopted for erosion prediction. Using the method proposed in this article, the erosion characteristics of two types of injectors widely used are studied, and the effects of injector opening and particle size are analyzed. For the first time, numerical simulation physically reproduces the uneven erosion on the needle surface, which is consistent with field observations. The simulation results reveal that the increased erosion on the needle surface downstream of the needle guide is attributed to the secondary flow induced by the Karman Vortex Shedding.Based on the E-L method, the numerical approach of sediment-laden flow is developed and for the first time applied to the unsteady water-air-sediment flow in rotating buckets. In this method, a new "impact-rebound" model is proposed to predict the particle trajectories after hitting the rotating wall. The proposed method is verified by a theoretical model from the literature. Based on the new method established, the distribution and aggregation characteristics of the sediment particles in the buckets with different openings and different particle sizes are discussed. It is found that the particles have a tendency to separate from the streamline, and this tendency will be affected by the location of the particles, the local curvature of buckets, and the velocity of the water sheet.Furthermore, based on the above method, a cumulative erosion prediction method has been developed and successfully applied to the erosion prediction of the rotating buckets. This method is established by firstly modifying the impact properties due to the rotation of buckets. These obtained values are then used to calculate the erosion during a single time step, based on which the cumulative erosion can be obtained when the flow advances. Based on the proposed method, the evolution of the erosion characteristics of rotating buckets under different openings and different particle sizes are analyzed. The simulation results are verified through the field observation results. Results show that the generated water sheet on the curved surface near the cutout and splitter acts as a shielding layer to prevent the particles in the jet from directly impacting the walls and consequently reduces the local erosion.The research in this paper reveals the mechanism of the sediment-laden flow and erosion, which can be useful for the optimization of Pelton turbines to reduce erosion in the future.