Cooled gas turbine transition duct

A transition duct for conveying hot combustion gas from a combustor to a turbine in a gas turbine engine, the transition duct comprising:

• a plurality of panels joined together to form a duct comprising a generally cylindrical inlet end and a generally rectangular outlet end disposed radially inwardly of the inlet end when installed in the gas turbine engine;
• a double bend region formed in a first of the panels;
• a stiffening rib end region in a second of the panels proximate an end of a stiffening rib joined to an outside surface of the second of the panels;
• a plurality of cooling structures formed in the panels for passing respective flows of cooling air through the panels;
• and
• wherein the cooling structures are formed to avoid both the double bend region and the stiffening rib end region.

A transition duct for conveying hot combustion gas from a combustor to a turbine in a gas turbine engine, the transition duct comprising:

• a plurality of panels joined together to form a duct comprising a generally cylindrical inlet end and a generally rectangular outlet end disposed radially inwardly of the inlet end when installed in the gas turbine engine;
• the outlet end comprising an outlet mouth formed to extend across at least approximately a 45° arc of a turbine inlet;
• a stiffening rib end region in one of the panels proximate an end of a stiffening rib joined to an outside surface of the one of the panels;
• a plurality of subsurface cooling passages formed through the one of the panels, each subsurface cooling passage having an inlet opening to an outside surface of the duct and an outlet opening to an inside surface of the duct;
• and
• wherein the cooling passages are formed to avoid the stiffening rib end region.