Consideration of Simplified Structural Models for Turbine Vane Modal Analysis

Modal analysis of jet engine hardware is a critical analytical tool utilized by engineers to understand and predict the vibrational risks to the system. Whereas blades and disks are critically analyzed due to their significant failure modes and effects, turbine vanes also need to be evaluated with respect to their design modal criteria to minimize potential risks to the engine system. Although full hoop models of the entire system are most accurate, the time required for modeling and solution processing is inhibitive. Through cyclic symmetry and the use of commercial contact techniques, an analytical model is created that provides the behavior of the entire system with a fraction of the computing time. However, subsequent simplification to a vane-only model has not been addressed and the potential for this model type to accurately predict system modes is of interest. This paper studies the finite element modeling procedures for turbine vane modal analysis using multiple contact methods and cyclic symmetry. An emphasis is placed on vane-only modeling techniques with a correlation to assembly model results for finite element model solution efficiency. Formal recommendations are offered for structural modeling of turbine vanes, including assessments of accuracy, loss in frequency prediction, and computational efficiency gain.

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