Fuel Nozzle Coking Analysis due to Soak-Back in a Gas Turbine Combustor(Abstract)

摘要

This study examines coking in gas turbine fuel nozzles due to heat soak-back. As the engine shuts down, it has been experimentally observed that excess heat builds up in the combustion chamber. Primarily composed of free convection (due to the stagnant air in contact with hot parts), this excess heat causes the premature coking of the top fuel injection nozzles as the buoyant hot air tends to reach the upper section of the chamber. These abnormally high temperatures cause coking of the fuel wetted surfaces for the fuel delivery system. This phenomenon is considered the main reason for frequent overhauls and aircraft downtime. In order to find solutions to prevent excessive maintenance costs for the engine, heat soak-back has to be clearly understood. For that purpose, the study was divided in two distinctive sections. The first consists in evaluating the heat soak-back in the engine using CFD while the second uses available experimental data to propose a model for coking prediction.