An engine experiment has been carried out to investigate Fan Stability and response to ambient wind conditions during static high power running of a modern large turbofan engine. This paper describes the experiment and the conclusions. Intermittently the inlet would separate and drive the fan into stall from which it did not recover when the inlet cleared up: on high working lines one inlet separation could stall the fan; on lower working lines the inlet separation / fan flow / bypass duct pressure would develop a divergent 10Hz oscillation which could eventually stall the fan. The interaction of the stalled fan with the turbine and mixed nozzle would then raise the fan running line above the stall dropout level thus locking the fan into stall even when the inlet cleared up. A one dimensional dynamic model of the engine was created that would exhibit similar behaviour to the engine when a delay was introduced between the inlet loss and fan face loss. The engine never showed steady operation with the inlet separated.

The new algorithm provides closed-loop control of the LP Compressor working line in such a way as to maintain compressor stability and to provide increased power from the engine at the same firing temperature. This method is intended for the Trent 60, an aero-derivative engine designated for power generation and mechanical drive applications. The power benefit is achieved by operating at higher LPC pressure ratio and thereby increasing the inlet air flow and overall pressure ratio of the engine. Since the algorithm controls the working line, the threats to compressor stability related to the working line level are removed (including production scatter, deterioration and fouling) and the required surge margin can be safely reduced, providing a significant benefit in engine performance. The paper presents comparatively the structure of the current and new concepts, the main features of the controller and stresses the improved accuracy and reliability of new algorithms. The performance benefit is then assessed; the increase in power is about 3% at ISO, sea level conditions and varies with ambient temperature.

No abstract

The new algorithm provides closed-loop control of the LP compressor working line in such a way as to maintain compressor stability and to provide increased power from the engine at the same firing temperature. This method is intended for the Trent 60, an aeroderivative engine designated for power generation and mechanical drive applications. The power benefit is achieved by operating at higher LPC pressure ratio and thereby increasing the inlet air flow and overall pressure ratio of the engine. Since the algorithm controls the working line, the threats to compressor stability related to the working line level are removed (including production scatter, deterioration, and fouling) and the required surge margin can be safely reduced, providing a significant benefit in engine performance. The paper presents comparatively the structure of the current and new concepts, the main features of the controller, and stresses the improved accuracy and reliability of new algorithms. The performance benefit is then assessed; the increase in power is about 3% at ISO, sea level conditions and varies with ambient temperature.