GAS TURBINE BLADE STRESS AND TEMPERATURE SENSITIVITY TO TURBINE INLET PROFILE AND COOLING FLOW

Actual operating conditions in the hot section of a gas turbine vary from the design condition due to factors such as geographic location, component wear, and fuel composition. Turbine design practices typically use a conservative approach that requires checking the sensitivity of operating parameters such as turbine inlet profiles, cooling flows, and heat transfer correlations on component temperatures and stresses. In most cases, a sensitivity check is limited to analyzing the bounds of a range of values for only a few input parameters, whereby the inputs that produce the most conservative results are carried through the remainder of the analysis. For flow path components, however, multiple inputs must be evaluated over a range of values due to the interaction of the hot gas flow field and internal cooling systems. The study presented in this paper uses a probabilistic approach to develop surrogate models to evaluate the sensitivity of a set of operating parameters on the predicted blade temperatures and stresses. Commercially available software is utilized to predict blade temperatures and stresses for the first two stages of an industrial gas turbine. The operating parameters define the blade cooling flow and the shape and values of the turbine inlet profiles of total temperature and total pressure. The results of the study show the spatially resolved sensitivity of the operating parameters on blade temperature and stress distributions.