Gas turbine engine with a transition duct and corresponding method of manufacturing a transition duct

A gas turbine engine comprising:

• a combustor, a turbine and a transition duct,
• wherein the transition duct is located between the combustor and the turbine to channel hot gas from the combustor to the turbine,
• wherein the transition duct comprises an internal surface on which the hot gas impinges to cause a varying temperature profile that forms a plurality of isotherms over the internal surface,
• a thermal barrier coating which is located on the internal surface and comprises at a first thermal barrier coating patch and a second thermal barrier coating patch, wherein the first thermal barrier coating patch:
• comprises a first thickness that is constant;
• is located on the internal surface;
• spans a plurality of relatively lower temperature isotherms of the plurality of isotherms;
• and is bounded by a first patch boundary that follows a coolest isotherm of the plurality of relatively lower temperature isotherms during operation, and
• wherein the second thermal barrier coating patch:
• comprises a second thickness that is constant and thicker than the first thickness;
• is located on the internal surface, spans a plurality of relatively higher temperature isotherms of the plurality of isotherms during the operation, and is bounded by a second patch boundary that follows a coolest isotherm of the plurality of relatively higher temperature isotherms during the operation.