Innovative Design of Attachment for Turbine Blade Rotating at High Speed

Abstract

There is evidence of a lack of knowledge in the design of the blade/disk attachment so that the strength of the materials is not fully exploited and the load capability of the attachment is underestimated. The aim of this work is to improve the engineers’ capability in designing the attachment so that higher loads can be carried with the same material. To this end, an optimization method has been applied to the attachment design. A dovetail blade root was chosen as case study and the objective function was the static equivalent stress in the blade and the disc. The dovetail was described by variable parameters under geometrical and physical constraints. Optimization was performed with a Genetic Algorithm (GA). The result of the optimization procedure is the optimal set of parameter values that minimizes the equivalent stress on the critical areas. Moreover, a surrogate function was utilized as a booster to the GA to save computational time. Stress analysis was performed with a commercial Finite Element (FE) software to provide the exact fitness value. An in-house code was developed to manage both the optimization process and the input/output interface with the FE software. The same code provides a decision-making core. This core checks for feasibility of the geometry of the current set of parameters. The expected result is an optimized profile in terms of Von-Misses equivalent stress.