An Empirical Model for Predicting Crack Growth Behavior of Gas Turbine Stage 1 Nozzles

摘要

Expenditure of maintenance cost for gas turbines can be greatly reduced if the parts can be well managed during the service to avoid excessive fallout rate or unplanned forced outage. In order to achieve the optimum part life management plan, the ability to accurately predict the life capabilities and fallout rates of the life limiting components becomes very important. An empirical model for the stage 1 nozzle of F-class frame 9 GE gas turbine has been developed based on Weibull statistic analysis of measured crack dimensions at observed critical locations of the nozzle. The crack measurements were taken during the hot gas path inspections and data from several different machine units which had different operating histories were used to establish relationship between Weibull parameters and elapsed operation histories. The fallout rate as function operation history is predicted by performing a Monte Carlo analysis to account for the combined effects of multiple cracks.