Jet engines have to be overhauled regularly in order to maintain a high efficiency and safety level. Depending on their condition, especially turbine blades have to be replaced, refurbished, or in case of low wear they are reusable without repair. Thus, significant geometry variances can occur in turbine blades due to operation and regeneration which affect the efficiency, the loads, and the lifetime of the blade. The present study addresses the effect of regeneration-induced geometry variances on the aerodynamic performance of the final low-pressure turbine (LPT) stage of a real jet engine. The geometry variances were determined by characteristic airfoil parameters, which were themselves derived from measured turbine blades. In order to analyze the effect of the variances of the geometry on the aerodynamic performance, a probabilistic simulations framework was developed. This consists of a blade parameterization model, a modeling procedure for geometry variations, and quasi3D(Q3D) CFD simulations. It is shown that the effect of regeneration-induced variances is dependent on the operating point. The largest scatter of isentropic efficiency and stage loading coefficient occurs during approach. In comparison, in take-off and cruise conditions the effect on the aerodynamic performance is slightly lower. Based on a sensitivity analysis, the stagger angle and the trailing-edge thickness are identified as the most important parameters affecting the LPT performance characteristic.
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