Pattern Factor Control Based on Fuel Modulation and Passive Optical Sensors

The proposed research addresses the need for flight-worthy combustion pattern factor control suitable for integration into new and legacy aircraft. The proposed system achieves operating-point control using fuel modulation, passive optical sensors and the full authority digital engine control (FADEC) to identify local temperature excursions and trims fuel flow to reduce overall pattern factor. Miniature sensors integrated into the fuel nozzles collect radiation emitted by the combustion gases and process multiple spectral bands to produce an intensity-independent output. Because the sensors are distributed around the annulus, they provide redundant, overlapping spatial information on the combustion. 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 identified combinations of optical signals that track fuel/air ratio in staged combustors. In Phase II, we will use a flexible prototype optical system to measure in a multi-injector high-pressure combustor the relationships between fuel modulation, pattern factor and sensor signals, and their sensitivity to field of view, and we will demonstrate control using operator-in-loop testing. The results will be used to design a Phase III commercial system.