Published Online:November 2025
Product Name:The IUP Journal of Mechanical Engineering
Product Type:Article
Product Code:IJME031125
DOI:10.71329/IUPJMECH/2025.18.4.43-59
Author Name:Rahul Basu
Availability:YES
Subject/Domain:Engineering
Download Format:PDF
Pages:43-59
The paper presents a comprehensive stability and whirl analysis of a concentric two-spool rotor system, such as GE F404 turbofan, incorporating an intershaft bearing. Finite element method (FEM) is used to derive mass, stiffness, damping, and gyroscopic matrices of each spool, which are then assembled to construct the global dynamic system. To assess stability, Routh-Hurwitz criterion is applied analytically to the characteristic polynomial of the state-space model, enabling symbolic insights into parameter sensitivity. The system is further analyzed using a trained neural network (NN), achieving 96.3% predictive accuracy over a dataset of 2400 simulations, to identify safe operating zones and validate model predictions. The results indicate that optimal placement and damping of the intershaft bearing increase the stability margin by up to 30%, mitigating sub-synchronous whirl modes. The approach integrates physical modeling and data-driven learning, offering a novel and interpretable framework for rotor dynamic design.
Multispool rotor engines are used widely due to their efficiency in high-speed applications.