Pattern Factor Control Based on Fuel Modulation and Passive Optical Sensors

The proposed research addresses the design and testing of a flight-worthy combustion pattern factor control system, suitable for integration into legacy aircraft. Operating point control would be achieved using fuel modulation, passive optical sensors, and the FADEC to identify aberrant fuel injectors and trim fuel flow to reduce overall pattern factor. Miniature sensors, which would be integrated into existing engine components, would collect radiation emitted by the hot gas and process multiple-spectral bands to produce a moderate frequency (order 100 HZ), intensity-independent control signal. Multiple sensors, distributed around the annulus would provide redundant, overlapping information on local and global combustion properties. Logic in the FADEC would identify an association between a specific fuel injector and increased temperature pattern factor, and modify the fuel flow accordingly. In Phase I we will perform a detailed engineering evaluation of the spectral, spatial, and temporal information available for sensor operation, and identify and rank candidate sensor and control schemes. In Phase II, we will use a flexible prototype to make measurements of the functional relationships between fuel modulation, pattern factor, and sensor signals in a multi-injector high-pressure combustor. Control relationship(s) will be demonstrated in open loop tests.