Abstract
abstract Heat shield is one of the important parts in aero engine, its function is to effectively prevent engine overheating. Under normal operation, the heat shield is subjected to high temperature from the combustion chamber and pressure pulsations inside and outside, and the phase difference of this pulsation pressure results in a very harsh working environment. Based on the experimental results, the approximate equation of the pulsating pressure is established, and the finite element method (FEM) is used to simulate the pulsating pressure. Meanwhile, the mechanical quantities such as thermal stress and mechanical stress are considered comprehensively. Linear elastic fracture mechanics (LEFM), Paris and Forman-Newman-de Koning (FNK) models were employed during the study in order to calculate the fatigue crack propagation life (FCPL) of the heat shield. The results show that the heat shield has an infinite lifetime at a phase difference of zero. As the phase difference increases, the FCPL and critical crack length (CCL) tend to decrease nonlinearly. When the phase difference is π, the FCPL and CCL are the shortest, which are only 3% and 17.1% of those at π/6. This study can provide a reference for the improvement and overhaul of heat shields.
Published Version
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