Crack propagation mechanism and life prediction of liner under thermal fatigue loads

To address the crack propagation issue in thin-walled multi-inclined-hole liners of aero-engine combustion chambers during service, a high-fidelity thermo-fluid-structure interaction (TFSI) numerical methodology was systematically developed in conjunction with experimental validation to elucidate the crack propagation mechanisms and the influence of initial crack parameters on remaining life characteristics. Research findings demonstrate that increases in both initial crack opening angle α₀ and azimuth angle β₀ significantly prolong the remaining life N, with their positive correlation to N strengthening as these parameters increase concurrently. Conversely, augmenting initial crack length L₀ leads to a substantial reduction in N, although the decay rate diminishes with increasing L₀. The angular intervals α₀∈[45°,60°] and β₀∈[15°,30°] are defined as the remaining life enhancement region for crack propagation. Furthermore, an echo state network (ESN)-based surrogate model with superior training efficiency and small-sample handling capability was developed, achieving an average relative error below 5% in predicting liner crack propagation life. This work provides robust theoretical support for condition monitoring and maintenance decision-making in aero-engine liners.