System and method for fuel nozzle cleaning during engine operation

A method for cleaning a fuel nozzle during operation of a heat engine including a compressor section, a combustion chamber, and a fuel system, the method comprising:

• operating the compressor section to provide a flow of oxidizer at a first oxidizer flow condition to the combustion chamber, wherein the first oxidizer flow condition comprises an environmental parameter, wherein the environmental parameter comprises a temperature parameter and a pressure parameter;
• operating the fuel system at a first fuel flow condition to produce a fuel-oxidizer ratio at the combustion chamber;
• comparing the environmental parameter to a first environmental parameter threshold, wherein the first environmental parameter threshold corresponds to one or more of a temperature of the flow of oxidizer or a pressure of the flow of oxidizer;
• comparing the environmental parameter to a second environmental parameter threshold, wherein the second environmental parameter threshold corresponds to one or more of a temperature of the flow of oxidizer or a pressure of the flow of oxidizer;
• and
• transitioning the fuel system to a second fuel flow condition corresponding to a cleaning condition at the fuel nozzle if the environmental parameter is equal to or greater than the first environmental parameter threshold and if the environmental parameter is equal to or less than the second environmental parameter threshold.