Life Consumption Assessment of a Large Jet Engine

This paper deals with the performance study and life consumption assessment of a long range civil aircraft engine with respect to take-off variables like airport altitude, ambient temperature, thrust levels, and flight duration. The component selected for lifing analysis is the first stage high pressure turbine blade/disk of a 430 kN thrust engine. Performance tools like TURBOMATCH and HERMES are validated against the published data, with deviation less than 4%. Based on failure modes like low cycle fatigue, creep, and oxidation, the integrated lifing tool is used to estimate the severity indices at various off-design conditions. It is observed that creep is the main criteria in blade failure due to extreme high temperature gas coming from combustor, whereas for disk it is fatigue due to repeated stresses with varying shaft speeds. With increase in airport altitude, the blade and disk severity increases with respect to that at sea level conditions. As the ambient temperature goes up, blade severity also increases as well but the change in disk severity is not as much due to less change in spool speed. Operating with reduced thrust, both the blade and disk severity decreases with deratings. As flight duration increases with reference to a standard mission, both the component damages go up but the blade severity is more pronounced than the disk due to exposure to high temperature for a long time. As a whole, the total damage severity of disk and blade assembly increases with rise in altitude, outside air temperature, and mission duration and decreases with engine deratings.