Gas Turbine Blade Characterization Through Modal Analysis

Area of Science:

• Materials Science
• Mechanical Engineering
• Aerospace Engineering

Background:

• Gas turbine blades require precise dynamic characterization for performance and safety.
• Nickel-based superalloys are critical for high-temperature applications, but their anisotropic behavior complicates modeling.

Purpose of the Study:

• To dynamically characterize gas turbine blades made from René 80 and directionally solidified (DS) nickel-based superalloys.
• To identify and mitigate discrepancies between experimental and numerical natural frequencies.
• To develop a robust framework for validating turbine blade dynamic behavior.

Main Methods:

• Development and validation of detailed, mesh-independent finite-element models from CAD geometry.
• Investigation of factors influencing modal predictions: geometry, test configuration, material anisotropy, and internal turbulators.
• Statistical analysis of dimensional variations and evaluation of grain orientation effects in DS superalloys.
• Application of tuning strategies, including elastic moduli adjustment, for model optimization.

Main Results:

• Dimensional variations showed no significant correlation with frequency scatter.
• Inclusion of turbulators reduced prediction errors for the first two modes by 2-3%.
• Adjusting elastic moduli (Ex, Ez) reduced modal frequency deviations to below 1% for the first two modes.

Conclusions:

• Finite-element model fidelity, particularly including internal turbulators, is crucial for accurate dynamic predictions.
• A methodology was established to optimize models, achieving high accuracy for gas turbine blade dynamic behavior.
• The validated framework supports diverse materials and manufacturing conditions in turbine blade development.