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Wear of runner blades is a common problem affecting the operational reliability of turbines with high head and high sediment content. In order to accurately predict the wear of the turbine runner blade, based on the solid-liquid two-phase flow equation and turbulence model, the full channel numerical simulation of the internal water and sediment flow was carried out, and the sediment volume distribution and sand water velocity on the turbine runner blade were obtained. Then, according to the digital simulation results and the operating parameters of the turbine runner, the sediment wear test scheme for the turbine blade material specimen is designed, and the sediment wear test is carried out on the runner material. According to the test results, the sediment wear curve of runner blade material is obtained and applied to numerical simulation, and the main position and wear degree of turbine blade sediment erosion are predicted. The inspection results of the runner blade wear after the unit has operated for a flood season show that obvious wear can be seen at the outlet edge of the lower band of the runner blade, and the wear position and wear amount are basically consistent with the simulation values. The study is of great importance for predicting the wear of turbine runner blades with high drop height and high sediment content, and for turbine maintenance under complex conditions.

A higher hardness carburized layer was formed on the surface of purity titanium by a double glow plasma hydrogen-free carburizing technique depending on glow discharge and hollow cathode effect. High purity solid graphite was used as a source cathode and purity titanium was used as the cathode materials. Experimental results indicate that higher hardness TiC phase and dissociate state carbon antifrictionphase were formed in the carburized layer. The carbon concentration and the hardness of carburized layer distribute in the gradient along the carburized layer from the surface to the inner. The surface hardness increases more than two times. Friction coefficient of Ti materials treated by hydrogen-free carburizing reduces by about 1/2.

Conventional reliability models of belt drive systems in the failure mode of fatigue are mainly based on the static stress strength interference model and its extended models, which cannot consider dynamic factors in the operational duration and be used for further availability analysis. In this paper, time-dependent reliability models, failure rate models and availability models of belt drive systems are developed based on the system dynamic equations with the dynamic stress and the material property degradation taken into account. In the proposed models, dynamic failure dependence and imperfect maintenance are taken into consideration. Furthermore, the issue of time scale inconsistency between system failure rate and system availability is proposed and addressed in the proposed system availability models. Besides, Monte Carlo simulations are carried out to validate the established models. The results from the proposed models and those from the Monte Carlo simulations show a consistency. Furthermore, the case studies show that the failure dependence, imperfect maintenance and the time scale inconsistency have significant influences on system availability. The independence assumption about the belt drive systems results in underestimations of both reliability and availability. Moreover, the neglect of the time scale inconsistency causes the underestimate of the system availability. Meanwhile, these influences show obvious time-dependent characteristics.