Development and Modeling of Angled Effusion Cooling for the BR715 Low Emission Staged Combustor Core Demonstrator

A technology program was started in 1994 within the framework of the German Aeronautics Research Program to develop axial staged combustor technology up to a core engine demonstrator. The objective was to demonstrate a 50% NOx reduction against the ICAO CAEP II limit without any compromise on the CO, UHC and smoke emission level compared to the latest single annular combustor technology. All other requirements, like ignition and relight capability, stability, durability and turbine inlet temperature traverse, were set equal to today’s state-of-the-art combustors. The combustor cooling concept chosen was of the angled effusion type. Development of adequate modeling techniques and steady-state and transient rig tests to calibrate the thermal models was the key factor for the success of the project. Despite the 15% increase in cooled surface, the overall combustor flow fraction required for cooling was reduced by 15% without any change in the combustor liner material from that of the in-service single annular combustor of the BR715. The axially staged combustor technology developed in the described program enables RR Deutschland to offer a staged combustor for the BR715 within the usual timescale of an engine certification process. It also forms the basis for future combustor technology to limit NOx-emissions for advanced engine cycles.