Liquid drop impact on solid surface with application to water drop erosion on turbine blades, Part II: Axisymmetric solution and erosion analysis

Based on the nonlinear mathematic model and computational method of liquid drop-solid impact established in Part I, in this paper, the quasi-3-D (axisymmetric) impact process is simulated and the results are specified for water drop impact on 1Cr13, with impact speed varying from 10 to 500 m/s. When dimensionless parameters are used to describe the impact procedure, the effect of water drop size is normalized. Both the transient pressure distribution in the liquid (including shock wave) and the transient stress distribution in the solid are obtained, and the magnitude and position of the maximum equivalent stress are given. The relationship between the most important parameters characterizing impact and incident speed is established, and simple formulae are fitted for the maximum stress, influence duration time, and influence zone size. Next, water drop erosion is analyzed for repetitive impact. With the statistics of water drop impact in a typical blade channel upon full and reduced load conditions, a simple fatigue model is employed to obtain the lifetime map on the blade surface, in terms of both impact times and operation hours. The most dangerous water drop erosion regions and operating conditions of the steam turbine blade are deduced. These results are useful to evaluate the water drop erosion mechanisms based on the fundamental solution of liquid-solid impact.