Film effectiveness enhancement using tangential effusion

Abstract

Film effectiveness enhancement is provided by a plurality of tangentially angled effusion holes in a combustor liner. The effusion holes positioned in the initial flow region at the start of the panel have a tangential angle between about 75° and about 90° to the combustor axis. The tangential angle of the effusion holes positioned downstream from the initial flow region is gradually reduced to a value corresponding to the bulk swirl of the combustor internal flow or to zero so that the effusion hole orientation at the end of the panel corresponds to that of convention effusion.

Description

BACKGROUND OF THE INVENTION [0001] The present invention generally relates to gas turbine engines and, more particularly, to effusion cooled components, such as combustor liners. [0002] An important component of any gas turbine engine is the combustor. Because of the high temperatures (>3500° F.) generated inside the combustor and because metals used in combustor construction are limited to 1700-1800° F., cooling must be provided for the combustor liner walls. [0003] Effusion cooling is a widely used technique for protecting gas turbine combustor liner walls from hot combustion gases. This cooling technique involves covering the combustor wall with a matrix of small holes. A supply of cooling air is passed through the holes from the cooler surface of the combustor wall to the surface exposed to higher temperatures. The cooling air actively cools the liner by convection as it passes through the hole and after the cooling air is discharged. [0004] The holes are usually 0.015 to 0.0...

AI Technical Summary

Benefits of technology

[0015] In a further aspect of the present invention, a method of enhancing the film effectiveness for an effusion cooled component comprises the step of passing a first portion of effusion flow through a plurality of initial effusion hole openings in an initial flow region of said effusion cooled component, at least one initial effusion hole opening positioned such that a longitudinal line of the effusion cooled component and a centerline of the initial effusion hole opening forms an initial hole tangential angle of between about 75° and about 90°.

Problems solved by technology

Although conventional effusion cooling may be sufficient for cooling some areas of the combustor liners, other areas of the liner are not cooled sufficiently and require additional cooling.

Although these groups of oppositely directed effusion holes may be useful in cooling hot spot areas caused by cooling film disruption, they are not useful in cooling all hot spot areas of the liner.

Although these rectangular holes may increase cooling in the cooling film shadow area caused by the dilution holes, they may not provide sufficient cooling in the initial flow region at the forward end of the liner.

The initial low film effectiveness is because conventional effusion requires 5-10 rows of effusion holes for the cooling film to develop such that the combustor wall is protected from the hot combustion gases.

The necessity of using starter skirts complicates the construction of combustors and increases their cost.

Also, in situations where the geometry does not permit the use of a starter skirt or where the effusion panel is very short, the usefulness of effusion cooling is greatly reduced.

Further, cooling augmentation is needed for applications where a starter film cooling skirt cannot be used.

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