Comprehension of thermomechanical phenomena and material behavior during high speed contact

Abstract

Civil aircraft engines present a wide range of labyrinth seals to ensure a good airtightness between the different components of the secondary air system. An increase in efficiency requires lower clearances gaps. As a consequence, brief contacts between rotating and stationary parts may occur especially during the engine running-in period. Such events can cause critical situations (seizure…) depending on the working conditions. In this paper, experimental simulations by means of a high-speed contact test device (76 m s−1) was developed to precisely recreate the friction conditions occurring in a turboshaft labyrinth seal and to better understand the material behavior in such tribological cases. This device was instrumented to carry out mechanical (axial and tangential forces and torque) and thermal measurements (IR camera and pyrometer). An experimental campaign was carried to study the contact between a Ti6Al4V rotor and an abradable coating of Al-Si polyester. Presented results show the complex interactions that strongly depend on the way the worn material behaves in the contact area. Local interaction dynamics are analysed with regards to mechanical and thermal measurements with different rotating speeds, incursion depths, and interaction speeds.