Methods of determining sensor probe location in a closed loop emissions control system

A method of operating a gas turbine engine, said method comprising:

• determining, at different locations, a plurality of temperature contour profiles for exhaust flowing through an exhaust duct, the exhaust having at least one emissions component entrained therein;
• selecting an emissions component entrained in the exhaust to be measured;
• determining a desired sensor probe installation location based on the emissions component to be measured and based on the plurality of temperature contour profiles;
• and
• adjusting at least one of a loading and operation of the gas turbine engine based on a concentration of the emissions component measured by the sensor probe installed in the desired sensor probe installation location.