Impingement cooled transition duct

• US 4,719,748 A
• Filed: 12/15/1986
• Issued: 01/19/1988
• Est. Priority Date: 05/14/1985
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Goodwin, Walter W., Steber, Charles E., Davis, Lewis B. Jr.
• Primary Examiner(s): Casaregola, Louis J.
• Assistant Examiner(s): Stout, Donald E.
• Application Number:
  US06/941,580
• Time in Patent Office: 400 Days
• Field of Search: 60/39.83, 60/760, 60/757, 60/758, 60/759, 60/754, 60/751, 60/39.37
• US Class Current: 60/39.37
• CPC Class Codes: F01D 25/12 Cooling
• CPC Class Codes: F01D 5/187 Convection cooling
• CPC Class Codes: F01D 9/023 Transition ducts between combustor cans and first stage of the turbine in gas-turbine engines; their cooling or sealings
• CPC Class Codes: F05D 2260/201 by impingement of a fluid
• CPC Class Codes: F05D 2260/202 by film cooling
• CPC Class Codes: F23R 2900/03044 Impingement cooled combustion chamber walls or subassemblies
• CPC Class Codes: F23R 3/002 Wall structures F23R3/02 and F23R3/007 take precedence
• CPC Class Codes: F23R 3/02 characterised by the air-flow or gas-flow configuration reverse- flow combustion chambers F23R3/54; cyclone or vortex type combustion chambers F23R3/58

Abstract

A transition duct in an advanced heavy duty gas turbine engine is cooled by impingement jets formed by apertures in a sleeve spaced a distance from the surface to be cooled. The sleeve is configured so as to duct spent impingement air towards the combustor, where it can be subsequently used for mixing with, and combustion of, the fuel, or for cooling of the combustor. The distance between the impingement sleeve and the transition duct surface is varied to control the velocity of air crossflow from spent impingement air in order to minimize the pressure loss due to crossflow. The cross-sectional areas of the apertures are varied to project impingement jets over the various distances and crossflow velocities. Generally, larger aperture areas are used with larger distances. The distance between the impingement sleeve and the transition duct systematically increases towards the combustor as the quantity of spent impingement air increases to a maximum value at the intersection of the combustor and the transition duct. The combination of variations in distance, aperture size, and inter-aperture spacing is utilized to vary the impingement cooling intensity to compensate for the variable internal heat load and also to produce the desired temperature distribution over the surface of the transition duct according to design requirements. The aforementioned variations are optimized to minimize the air flow pressure drop ahead of the combustion system which achieving the required cooling intensity according to design requirements.

Claims

1. An impingement cooling apparatus for cooling a surface of a transition duct disposed between a combustor and a turbine stage of a gas turbine engine, said transition duct being disposed in a compressed air plenum, comprising:

an impingement sleeve surrounding said transition duct and spaced a distance therefrom to form a flow volume therebetween;

a plurality of apertures in said impingement sleeve;

each of said plurality of apertures having an area;

adjacent ones of said plurality of apertures being separated by a spacing;

a closed end at a turbine end of said flow volume;

an exit at a combustor end of said flow volume;

a flow sleeve within the compressed air-plention surrounding said combustor;

a flared entry portion at an end of said flow sleeve overlapping said exit and forming an aerodynamic converging shape therebetween;

a flow of air through said aerodynamic converging shape flowing toward said combustor being effective to reduce a pressure at said exit below a pressure in said compressed air plenum whereby a pressure drop across said impingement sleeve produces an impingement jet of air from each of said plurality of apertures directed toward said transition duct; and

at least one of said distance, said area and said spacing being non-uniform over said impingement sleeve to control a cooling in said surface.

2. An impingement cooling apparatus according to claim 1 wherein said distance increases from said turbine end to said combustor end.

3. An impingement cooling apparatus according to claim 2 wherein said area increases from said turbine end to said combustor end.

4. An impingement cooling apparatus according to claim 3 wherein said spacing increases from said turbine end to said combustor end.

5. An impingement cooling apparatus according to claim 1 wherein said spacing, said distance and said area are non-uniform to tailor a cooling of said transition duct.

6. 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.

7. 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.

8. 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

9. 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.

10. 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.

11. The improved impingement cooled transition duct recited in claim 10 wherein the area and spacing of the apertures in the planar bottom are varied in accordance with the distance between the planar bottom and the surface of the transition duct.