Effect of Local Mistuning of Blade Vibration Frequencies on the Vibration Stress of Compressor and Turbine Disks of Aircraft Gas Turbine Engines

• Published in: Strength of materials Vol. 55; no. 1; pp. 12 - 24
• Main Authors: Zinkovskyi, A. P., Savchenko, K. V., Derkach, O. L., Tokar, I. G.
• Format: Journal Article
• Language: English
• Published: New York Springer US 2023; Springer; Springer Nature B.V
• Subjects: Aircraft; Aircraft engines; Aircraft reliability; Aircraft vibration; Amplitudes; Analysis; Blades; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Finite element method; Gas turbine engines; Gas-turbines; Localization; Low pressure; Materials Science; Mathematical analysis; Mistuning (turbomachinery); Resonant frequencies; Resonant vibration; Solid Mechanics; Stiffness; Thinning; Three dimensional models; Turbine disks; Vibration; Vibration analysis; frequency function; shrouded blades; bladed disk; intergroove rib; mistuning of blade vibration frequencies; vibration stress
• ISSN: 0039-2316; 1573-9325
• DOI: 10.1007/s11223-023-00498-4

The effect of engineering and process factors on the vibration stress of the cantilevered bladed disks of the 1st stage – low-pressure compressor and the shrouded blades of the 2nd stage – free power turbine for different types of aircraft gas turbine engines is investigated. The results of calculation-experimental studies on the frequency mistuning effect caused by the reduction of the cantilevered blade face length and its transition thinning to the shroud platform on the vibration stress of the intergroove ribs of the disk and blade rings, respectively, are presented. Three-dimensional finite element models of disks with the break of cyclic symmetry due to the vibration frequency mistuning of one blade, as the most dangerous case of the natural frequency scattering over the blade rings, were constructed. Calculation and experimental studies on the vibration stress of the intergroove ribs were carried out for two disk modifications with different rim thicknesses. The results of the complex calculation studies demonstrated that the resonant vibration amplitudes were localized in the vicinity of the frequency-mistuned blade. Thus, in the vicinity of the blades with the cross-section thinning of their face, the difference in the distribution of maximum equivalent stress zones is observed, which can lead to the localization of blade vibrations with their further failure. At the same time, the vibration stress of the intergroove ribs is established to depend on the vibration excitation harmonic, as well as the elastic bladed disk connection, which is determined by its stiffness. The results of computational experiments suggestive of reducing both the vibration stress and the localization level of resonant vibration amplitudes by analyzing and establishing those characteristics that effect the connection stiffness, which is of great practical importance for improving the vibration reliability of aircraft engine disks.