Remaining useful life prognostic of three-shaft gas turbine based on the low-pressure turbine outlet temperature

The rise of low-pressure turbine outlet temperature is a characterization of three-shaft gas turbine engine degradation. This paper provides three methods to predict the remaining useful life of three-shaft gas turbine engine, which are regression analysis of standard low-pressure turbine outlet temperature, relevance analysis and multiple regression, regression analysis of heat loss index obtained based on mathematical model of gas turbine. Example shows that the three methods all can predict the life. But in the first one the linear regression can't explain the temperature fluctuations well, and the predictions of the quadratic and cubic regression are not consistent with the actual situation. The multiple regression analysis takes the multiple monitoring parameters related to low pressure turbine outlet temperature into account, increasing the adjusted R-squared, but it couldn't consider the influence of compressor washing, and the prediction interval is large, which may not meet the needs of the project. The third method can accurately know and guide the compressor washing time according to certain degradation rate, and can predict remaining useful life effectively, which is a feasible way for gas turbine health assessment and maintenance decision-making.