关键词: 高温热带, 临界速度, 密封环, 有限元

Abstract: According to the characteristics of working conditions and structures of sealing rings, a modeling method is presented to simulate the appearance of local hot bandings on the seal frictional pair. Based on the Galerkin finite element formulation, the physical models with non-uniform characteristics and coupling relationships of physical fields are built including heat conduction, heat flux, perturbations of temperature field and so on. The formulations about the thermal instability of local hot banding are transformed into the determinants of matrixes, and the solutions are carried out. The critical speeds for the appearances of hot bandings are obtained under different frictional conditions. And the relationship curves between the critical speed and frictional coefficient, elastic modulus, thermal conductivity, coefficient of thermal expansion, and sealing ring size are determined. In addition to the thermal conductivity, other factors have significant effects on the critical speed. Experimental investigations are performed in the sealing performance test rig, by comparison of numerical and experimental critical speed results to enable an assessment of the accuracy level. Scanning electron microscopy is utilized to examine the surface morphology of the sealing rings. The obvious banding scratches are observed on the sealing surface under the condition that the experimental speeds are greater than the calculated critical speeds, which agree well with the characteristics of hot bandings. The numerical and experimental results indicate the effectiveness of the finite element discrete model on simulations of the thermal instability.

Key words: critical speed, finite element, hot banding, sealing ring