Computational Modeling of an Aircraft Engine Combustor to Achieve Target Exit Temperature Profiles

Abstract

A GE high bypass turbofan aircraft engine combustor has been successfully modeled in an effort to define liner cooling and dilution modifications necessary to create inboard peaked and flat exit temperature profiles. A fully elliptic three–dimensional body–fitted computational fluid dynamics code (CONCERT3D) was used to solve for the flow field variables. The modeling results provided detailed flow information that was used to define cooling and dilution modifications. Boundary condition flow levels for the model were derived from COBRA, a one–dimensional pressure driven flow distribution program. The complex inlet boundary conditions defining the combustor inlet swirl cup discharge flow were generated via a detailed CONCERT2D model. A baseline model was first created and tuned to match existing test results. Using the tuned model, dilution and cooling patterns were varied to analytically achieve the two desired temperature profiles. Approximately ten attempts were needed to match both target profiles. The derived changes were then applied to actual combustor hardware and new exit temperature profiles were measured in full component rig tests. Both tested configurations closely matched the target profiles on the first attempt, greatly reducing the number of hardware modifications and tests typically needed to fulfill profile requirements.