Method of operating a combustion system with main and pilot fuel circuits

A gas turbine engine comprising a combustion system, the combustion system comprising a fuel controller and a fuel nozzle defining a main fuel circuit and pilot fuel circuit, the fuel controller comprising one or more processors and one or more memory devices, the one or more memory devices storing instructions that when executed by the one or more processors cause the one or more processors to perform operations, the operations comprising:

• determining, via the fuel controller, an overall flow of fuel, the overall flow of fuel defining a sum total fuel through the main fuel circuit and the pilot fuel circuit;
• determining, via the fuel controller, a plurality of ranges of ratios of main fuel flow through the main fuel circuit versus pilot fuel flow through the pilot circuit from the overall flow of fuel, wherein each range of ratios is based on a combustion criterion different from one another;
• determining, via the fuel controller, a resultant range of ratios of main fuel flow versus pilot fuel flow based on a hierarchy of combustion criteria, wherein the hierarchy of combustion criteria provides a priority ranking of the combustion criterion;
• and
• flowing, through the fuel nozzle, the overall flow of fuel to the main fuel circuit and the pilot fuel circuit based on the resultant range of ratios of main fuel flow versus pilot fuel flow.