The effect of aerodynamic heat on the dynamics character of front body of assembling materials

摘要

Aerodynamic heating would generate high temperature rise on aero engine structure and severe temperature gradient on the body of assembling materials at the front of gas inlet which would develop heterogeneous temperature and thermal stress field and influence the kinetic characteristics of mechanical structure. In this paper, a finite element model of Ceramic-SiC front body has been built up. The heterogeneous temperature field inside the front body was computed from fluid flow and thermal conduction. The thermal stress was achieved by thermo-solid coupling computation with the boundary condition of temperature field and mode analysis of prestress was carried out by loading thermo stress on the front body. Under the environment of liquid-thermal-solid multi-field coupling, through the investigation on the inherent frequency and the variation of vibration type of the front body at different temperatures, the results show that the thermo vibration frequency of Ceramic-SiC front body aroused by the aerodynamic heat could be approximately replaced by the inherent frequency of normal temperature below 500°C, then a accelerated decrease of inherent frequency was observed when the temperature exceeded 600°C and the decline rate reached the maximum value at 1050°C. Over 10% relative difference of first order inherent frequency was obtained. Therefore the effect of aerodynamic heat on the inherent frequency should be considered during the design process and a configuration should be made especially on the low order inherent frequency.