Power plants – Combustion products used as motive fluid – Combustion products generator
Reexamination Certificate
1999-10-14
2001-07-31
Thorpe, Timothy S. (Department: 3746)
Power plants
Combustion products used as motive fluid
Combustion products generator
Reexamination Certificate
active
06266961
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to gas turbine engines and more particularly to film cooled combustor liners used in such engines.
A gas turbine engine includes a compressor that provides pressurized air to a combustor wherein the air is mixed with fuel and ignited for generating hot combustion gases. These gases flow downstream to one or more turbines that extract energy therefrom to power the compressor and provide useful work such as powering an aircraft in flight. Combustors used in aircraft engines typically include inner and outer combustor liners to protect the combustor and surrounding engine components from the intense heat generated by the combustion process. The combustor liners are cooled to meet life expectancy requirements.
Liner cooling is commonly provided by diverting a portion of the compressed air (which is relatively cool) and causing it to flow over the outer surfaces of the liners. In addition, a thin layer of cooling air is provided along the combustion side of the liners by directing cooling air flow through circumferentially disposed rows of cooling holes formed in the liners. This technique, referred to as film cooling, reduces the overall thermal load on the liners because the mass flow through the cooling holes dilutes the hot combustion gas next to the liner surfaces, and the flow through the holes provides convective cooling of the liner walls. In one known configuration, film cooling is accomplished by forming the liner with a plurality of integrally formed panel sections with a bump or nugget formed on the forward end of each panel section. A circumferentially disposed row of axially oriented cooling holes is formed in the nugget so that the thin film of cooling air is produced along the inner surface of the panel section.
While film cooling of combustor liners is generally quite effective, various conditions in gas turbine combustors can reduce the cooling film effectiveness in specific regions of the liners. For instance, due to various phenomena that commonly occur inside combustors, the heating load is not uniformly distributed about the liners. This leads to specific regions in the combustor that require additional cooling. Increasing the film cooling flow will solve this problem but results in excess cooling air for the regions that do not require additional cooling, thereby reducing engine performance. Accordingly, preferential cooling hole patterns have been developed wherein different hole diameters are used over the combustor so that additional cooling is provided only where needed.
One specific condition that can reduce cooling film effectiveness is the presence in the combustor liners of igniter towers that hold the igniters for initiating combustion in the combustor. The igniter towers disrupt the flow of cooling air over the combustor liners, thereby reducing the cooling film effectiveness behind them. Thus, regions of the liners immediately downstream of the igniter towers will be prone to a loss of cooling film effectiveness. This condition has been addressed by adding a set of radially oriented cooling holes to the nugget immediately downstream of the igniter towers as well as increasing the diameter of some of the axially oriented cooling holes in that nugget. However, because many different cooling hole sizes and patterns are employed, several tooling set-ups are required. This adds to the time and cost of manufacturing the liners.
Accordingly, there is a need for a combustor liner having a cooling scheme that optimizes cooling film effectiveness while minimizing tooling set-up requirements.
SUMMARY OF THE INVENTION
The above-mentioned need is met by the present invention which provides a gas turbine combustor liner that includes a first annular panel section having a first cooling nugget formed at one end thereof and a second annular panel section having a second cooling nugget formed at one end thereof. A first row of cooling holes is formed in the first cooling nugget, and a second row of cooling holes is formed in the second cooling nugget. The second row of cooling holes is arranged in a preferential cooling pattern including a plurality of arrays, each array has a first set of cooling holes having a first diameter and a second set of cooling holes having a second diameter that is smaller than the first diameter. At least one igniter tower is formed in the first annular panel section and is circumferentially aligned with one of the second sets of cooling holes.
The present invention and its advantages over the prior art will become apparent upon reading the following detailed description and the appended claims with reference to the accompanying drawings.
REFERENCES:
patent: 2979898 (1961-04-01), Ward
patent: 3978662 (1976-09-01), Dubell et al.
patent: 4622821 (1986-11-01), Madden
patent: 4700544 (1987-10-01), Fucci
patent: 5123248 (1992-06-01), Monty et al.
patent: 5181379 (1993-01-01), Wakeman et al.
patent: 5233828 (1993-08-01), Napoli
patent: 5279127 (1994-01-01), Napoli
patent: 5924288 (1999-07-01), Fortuna et al.
Howell Stephen J.
Waslo Jennifer
General Electric Company
Hess Andrew C.
Rodriguez W.
Thorpe Timothy S.
Young Rodney M.
LandOfFree
Film cooled combustor liner and method of making the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Film cooled combustor liner and method of making the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Film cooled combustor liner and method of making the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2475256