Impingement cooled transition duct

In a gas turbine of the type comprising a turbine casing connected to a compressed air supply and including within the turbine casing a plurality of combustors and transition ducts for delivering hot gas to a turbine stage;

• an improved impingement cooled transition duct wherein the improvement comprises:
• an impingement sleeve surrounding each transition duct approximately coextensive therewith and having one end adjacent the combustor and the other end adjacent the turbine stage, a closed end between the impingement sleeve and the transition duct at the turbine end;
• the impingement sleeve being spaced a radial distance from the transition duct along the axial length of the transition duct, said radial distance larger at the combustor end than at the turbine end;
• and,
• a plurality of apertures formed in the impingement sleeve, said apertures larger and spaced farther apart from one another at the combustor end than at the turbine end.

In a gas turbine of the type comprising a turbine casing connected to a compressed air supply and including within the turbine casing a plurality of combustors and transition ducts for delivering hot gas to a turbine stage;

• an improved impingement cooled transition duct wherein the improvement comprises:
• an impingement sleeve surrounding each transition duct approximately coextensive therewith and having one end adjacent the combustor and the other end adjacent the turbine stage, a closed end between the impingement sleeve and the transition duct at the turbine end;
• the impingement sleeve being spaced a radial distance from the transition duct along the axial length of the transition duct, said radial distance larger at the combustor end than at the turbine end;
• a plurality of apertures formed in the impingement sleeve, said apertures larger and spaced farther apart from one another at the combustor end than at the turbine end;
• and,
• a flow sleeve surrounding each combustor and approximately coextensive therewith, the flow sleeve including a flared entry portion overlapping an exit of the impingement sleeve to define an annular flow passage having a sufficient area whereby the airflow velocity in the annular flow passage exceeds the airflow velocity of the spent impingement air flow.

An impingement cooling sleeve for use in a gas turbine wherein the impingement sleeve is adapted to surround a transition duct interconnecting the discharge end of a combustor with the inlet end of a turbine, the surrounding impingement sleeve also having a corresponding combustor end and a turbine end;

• and, wherein the impingement sleeve comprises:
• an increasing flow volume from the turbine end to the combustor end;
• a plurality of apertures in the impingement cooling sleeve;
• each of the apertures increasing in area from the turbine end to the combustor end;
• the distance between apertures increasing from the turbine end to the combustor end;
• the turbine end of the impingement sleeve being sized for closed attachment to the transition duct at the turbine end;
• and,
• the combustor end of the impingement sleeve being sized larger than the combustor end of the transition duct to from an exit at the combustor end of the impingement sleeve

In a gas turbine of the type comprising a turbine casing connected to a compressed air supply and including within the turbine casing a plurality of combustors and transition ducts for delivering hot gas to a turbine stage;

• an improved impingement cooled transition duct wherein the improvement comprises:
• an impingement sleeve surrounding each transition duct approximately coextensive therewith and having one end adjacent the combustor and the other end adjacent the turbine stage, a closed end between the impingement sleeve and the transition duct at the turbine end;
• the impingement sleeve being spaced a radial distance from the transition duct along the axial length of the transition duct, said radial distance larger at the combustor end than at the turbine end;
• a plurality of apertures formed in the impingement sleeve, said apertures larger and spaced farther apart from one another at the combustor end than at the turbine end;
• a flow sleeve surrounding each combustor and approximately coextensive therewith;
• an annular seal between the flow sleeve and the impingement sleeve;
• and,
• a plurality of apertures formed in the flow sleeve whereby a portion of the compressed air supply which does not pass through the impingement sleeve is combined with the spent impingement air flow.

In a gas turbine of the type comprising a turbine casing connected to a compressed air supply and including within the turbine casing a plurality of combustors and transition ducts for delivering hot gas to a turbine stage;

• an improved impingement cooled transition duct wherein the improvement comprises:
• an impingement sleeve surrounding each transition duct approximately coextensive therewith and having one end adjacent the combustor and the other end adjacent the turbine stage, a closed end between the impingement sleeve and the transition duct at the turbine end;
• the impingement sleeve being spaced a radial distance from the transition duct along the axial length of the transition duct, said radial distance larger at the combustor end than at the turbine end;
• a plurality of apertures formed in the impingement sleeve, said apertures larger and spaced farther apart from one another at the combustor end than at the turbine end;
• and, wherein the improved transition duct includes an aft support having a continuous wall attached to the transition duct, the improvement further comprising:
• an impingement insert comprising a wall portion and a planar bottom tightly fitted within the aft support continuous wall and having the planar bottom spaced a distance from the transition duct surface;
• a plurality of apertures formed in the planar bottom for directing impingement air to the surface of the transition duct;
• and,
• a plurality of film cooling apertures in the transition duct whereby impingement cooling air is exhausted into the hot gas flow.