Patent Application
20150292742
1. Field of the Invention
The invention relates to combustor baskets for gas turbine engine combustors. More particularly, the invention relates to combustor baskets of the type having nested inner and outer liners separated by a cooling air gap.
2. Description of the Prior Art
Some known types of gas turbine engines having annular combustor construction incorporate combustor baskets with nested inner and outer liners, separated by a cooling air gap. The cooling air gap is maintained at the distal downstream tip of the basket by radially outwardly directed dimples formed in the inner basket distal tip that abut against the outer liner. A standoff gap is preserved between the respective liners so long as the dimples maintain structural integrity. The inner liner is in direct communication with the combusted gas flow, experiencing higher temperature exposure than the outer liner. The combustion gas thermal and fluid contact erodes and/or distorts the inner basket during engine operation. In some operating environments dimples formed on the inner liner distal tip erode or collapse, facilitating collapsing of the cooling gap between the inner and outer liners. Diminished cooling flow hastens further thermal erosion of the combustion basket. In an effort to improve cooling airflow in the combustor basket gap between the inner and outer liners, some combustor basket designs have incorporated through holes in the inner liner circumference, especially proximal the basket distal tip portion, in order to induce radial airflow into the gap as well as axial airflow.
Accordingly, a suggested object of embodiments of the invention is to maintain combustor basket cooling airflow in the gap between inner and outer liners during operation of the gas turbine engine.
Another object of embodiments of the invention is to maintain the invention is to combustor basket cooling airflow in the gap between inner and outer liners during operation of the gas turbine engine while preserving the option of forming cooling air through holes in the inner liner.
Yet another object of embodiments of the invention is to enhance combustor basket service life by maintaining combustor basket cooling airflow in in the gap between inner and outer liners during operation of the gas turbine engine.
These and other objects are achieved in one or more embodiments of the invention by a gas turbine engine combustor basket, which has nested outer and inner liners that are separated by a gap at their respective distal downstream ends for passage of cooling air between the liners. Radially inwardly projecting platefins formed on an inner circumferential surface of the outer liner maintain the cooling air passage gap. In some embodiments effusion cooling through holes are formed in the inner liner outer circumference, oriented in the air passage gap between the fins, so that cooling air passes through the effusion holes into the cooling air passage gap. By locating the platefins on the outer liner they are less susceptible to thermal erosion and distortion than previously known liner separation constructions that were located on the inner liner. Locating the platefins on the outer liner also facilitates inclusion of cooling through holes on the inner liner between the corresponding outer liner platefins, so that additional radial cooling flow is introduced into the gap between the liners. Combustor basket service life is enhanced by maintaining cooling airflow gap between the inner and outer liners.
Other embodiments of the invention feature a gas turbine engine including a turbine casing, which in turn includes therein a rotatable rotor as well as compressor, combustor and turbine sections. The combustor section has a plurality of nested outer and inner liners, respectively having axial length and radially spaced downstream distal ends. The respective liners form a gap between themselves for passage of cooling air.
Radially inwardly projecting platefins formed on an inner circumferential surface of each of the outer liners maintains the cooling air passage gap.
Additional embodiments of the invention feature method for cooling a gas turbine engine combustor basket, for passage of combustion gas there through. The method includes the steps of providing nesting outer and inner liners, respectively having axial length and radially spaced downstream distal ends; and forming radially inwardly projecting platefins on an inner circumferential surface of the outer liner. The inner liner is nested within the outer liner, so that distal tips of the platefins abut an outer circumference of the inner liner distal end, thereby forming a cooling air passage gap between the respective liners, for passage of cooling air. The combustor basket is installed within a gas turbine combustor. The engine is operated, so that cooling air passes through the cooling air passage gap.
The respective objects and features of the present invention may be applied jointly or severally in any combination or sub-combination by those skilled in the art.
The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.
After considering the following description, those skilled in the art will clearly realize that the teachings of embodiments of the invention can be readily utilized in a gas turbine engine combustor basket, which has nested outer and inner liners that are separated by a gap at their respective distal downstream ends for passage of cooling air between the liners. Radially inwardly projecting platefins formed on an inner circumferential surface of the outer liner maintain the cooling air passage gap. In some embodiments effusion cooling through holes are formed in the inner liner outer circumference, oriented in the air passage gap between the fins, so that cooling air passes through the effusion holes into the cooling air passage gap. By locating the platefins on the outer liner they are less susceptible to thermal erosion and distortion than previously known liner separation constructions that were located on the inner liner. Locating the platefins on the outer liner also facilitates inclusion of cooling through holes on the inner liner between the corresponding outer liner platefins, so that additional radial cooling flow is introduced into the gap between the liners.
Referring to
Cooling air flows axially through the gap 48 formed between the outer 44 and inner 46 liners, as shown schematically by the arrow FA shown in
Although various embodiments that incorporate the teachings of the present invention have been shown and described in detail herein, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings. The invention is not limited in its application to the exemplary embodiment details of construction and the arrangement of components set forth in the description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
