Parametric Optimization of Nozzle Turbine Vane Modal Characteristics by Means of Artificial System

Abstract

Modal analysis is a fundamental assessment in the design phase of a nozzle guide vane in a low pressure turbine system. Evaluation is crucial for new concept design but also in case of design modification. The technical requirement is to ensure appropriate durability level (number of flight cycles) and the reliability of the system. An understanding of dynamic behavior is one of the key elements in the high cycle fatigue (HCF) evaluation. Finite element method (FEM) analyses are widely used in new product introduction phases to verify modal characteristics with respect to operating range and engine orders (forcing function, excitation). In the process used 2D representation of the nozzle guide vane approximated by axisymmetric and plane stress with thickness FEM plain elements. The optimization process used geometrical parameters (nozzle outer band and casing shell) and surrogate models to find optimal solutions from a frequency placement perspective. A sensitivity analysis and optimization process revealed casing shell thickness to be a major contribution in the modal response and weight. Excluding casing shell parameters led to a lower frequency shift with respect to the reference configuration. The presented optimization framework is very robust and time effective in completing the optimization task together with a sensitivity analysis for the defined design domain. An FEM model validation of the surrogate model showed consistency in the modal analysis results. A promising solution from the component weight standpoint is the optimization with hook position and leaning only. A future research recommendation is to study an extended parameter range to reduce weight impact for this set.

Parametric Optimization of System Modes for Nozzle Turbine Vane by Means of Costimulated Artificial Immune System

“…The results are compared in the next section. The optimization loop uses a static metamodel [8] that is an approximation of the real phenomena concerning the model area and natural frequency. The algorithm is responsible for design space exploration, while the Ansys Workbench environment [15] is used to extract the natural frequency and mode shape of the geometrical configuration.…”

“…Sci. 2024, 14, x FOR PEER REVIEW 2 of 16 study presented in [8] revealed the additional impacts of the thicknesses, hook positions and leaning on the casing nozzle assembly. In the optimization process, an artificial immune system and a novel version of the algorithm based on costimulation were used.…”