Multistage Turbine Erosion

This paper presents a computer package developed to calculate the blade erosion rates in multistage turbines that use particle-laden hot expansion gases. This package is an extension of the single-stage erosion code presented in some of our earlier papers. The present package calculates gas flow and particle trajectories in each stage. The calculated particle outlet conditions of a given stage are processed statistically to generate the particle inlet conditions to the next stage enabling trajectory and erosion calculations to be advanced beyond a single turbine stage. The package allows erosion predictions to be obtained either based on the semi-empirical erosion formula presented earlier or by using an improved model which relies upon direct interpolation of available experimental data. This computer package has been applied to a four-stage electric utility gas turbine. It has been found that, in addition to the first-stage rotor blades, as indicated by our earlier studies, the second-stage rotor and the second and third-stage stator blades may also be exposed to critical erosion damage.