Synthetical Numerical Model for Evaluating Blade Fatigue Life of Liquid Corrosion in Steam Turbine

Abstract

Liquid corrosion of steam turbine blade has become an important reason for blade failure in supercritical parameter power plant and nuclear power plant. In order to improve the reliability of blades in wet steam stages of steam turbine and prevent blade failure from liquid corrosion, a nonlinear coupling wave model has been developed to investigate the high speed impact between ball liquid droplet and elastic solid, according to a mass of numerical results of impact between liquid droplet and elastic solid made by 1Cr13 which is a typical material for steam turbine blade, the relational expression between dimensionless equivalent peak stress and impact speed mach number is obtained. Then suitable equations to evaluate the fatigue life of crack initiation and nonlinear cumulative damage rule are adopted to develop numerical model for liquid corrosion fatigue life of blade, and the liquid corrosion fatigue life of a wet steam blade is analyzed in detail. It is shown that the nonlinear coupling wave model for impact and the analysis model of liquid corrosion fatigue life for blade can give some quantitative results, it may be helpful to evaluate liquid corrosion fatigue life of blade and prevent blade from liquid corrosion during blade design.