Method and system for controlling distortion of turbine case due to thermal variations

A system for controlling distortion of a turbine case, said system comprising:

• a thermal measurement system for measuring a temperature distribution for the turbine case, the temperature distribution comprising a plurality of thermal gradients;
• and
• a computer configured for:
• modeling a plurality of thermal stresses on the turbine case induced by the thermal gradients,
• calculating an out of roundness index resulting from the thermal stresses on the turbine case,
• comparing the out of roundness index with at least one distortion limit, and
• controlling the temperature distribution until the out of roundness index satisfies the distortion limit.

A method for controlling distortion of a gas turbine case, said method comprising:

• representing the gas turbine case as a plurality of sections;
• measuring a temperature distribution for the gas turbine case, the temperature distribution comprising a plurality of thermal data sets obtained at one or more measurement times, each thermal data set being obtained for a respective one of the sections and for the respective measurement time;
• calculating a sectional out of roundness index for each of the thermal data sets;
• comparing each sectional out of roundness index with a distortion limit;
• and
• controlling the temperature distribution until each of the sectional out of roundness indices satisfies the distortion limit.