Patent Application
20070062202
The field of invention relates generally to the design of combustors used in gas turbine engines and, more particularly, to an improved support boss for a combustor.
Like other components of a gas turbine engine, a combustor must be held in place using an appropriate supporting arrangement. Such arrangement may include arms extending between the combustor and the walls of the chamber in which the combustor is located. Most of the combustor is spaced apart from the walls of the chamber, thereby allowing air flowing around the combustor. One end of each arm is attached to the combustor using an attachment point referred to as a “support boss”.
As its name indicates, the combustor is the location where fuel is mixed with compressed air and burned. The hot combustion gases are then sent to the downstream turbine area of the gas turbine engine. The highly intense heat generated by the combustor generally requires the presence of a network of cooling orifices through the walls of the combustor. Air surrounding the combustor is then forced into these orifices, thereby maintaining a lower temperature at the walls of the combustor. However, conventional support bosses tend to create local hot spots because they do not allow the presence of cooling orifices. This generates stresses due to temperature gradients. Hot spots may also be created on a heat shield located underneath a conventional support boss. Heat shields are located inside the combustor and are spaced apart from the interior of the wall of the combustor. When no cooling air is provided, the heat shield is subjected to a higher temperature.
Accordingly, there is a need to provide an improved support boss which can mitigate the presence of hot spots on them or around surrounding parts.
In one aspect, the present invention provides a support boss for use in a combustor of a gas turbine engine, the support boss comprising a side wall defining an internal space, the side wall having at least one air inlet orifice; and a bottom wall closing one end of the internal space, the bottom wall having at least one air outlet orifice.
In another aspect, the present invention provides a support boss for a combustor of a gas turbine engine, the support boss comprising a side wall having opposite first and second ends, the side wall defining an internal space and being configured and disposed for receiving an end of a support arm on the first end thereof, the first end of the support boss being closed when the support arm is attached on the side wall; a bottom wall provided at the second end of the side wall; means for providing air inside the internal space; and means for retrieving air from inside the internal space.
In another aspect, the present invention provides a method of cooling a support boss attached to a combustor in a gas turbine engine, the method comprising providing air inside the support boss; and retrieving at least some of the air from inside the support boss and sending it inside the combustor.
Further details of these and other aspects of the present invention will be apparent from the detailed description and accompanying figures.
Reference is now made to the accompanying figures depicting aspects of the present invention, in which:
Each support boss 20 is attached to the periphery of a hole made through the wall 16a of the combustor 16, for instance using welding, brazing or the like. The wall 16a of the combustor 16 comprises cooling orifices 16b. It should be noted that most cooling orifices are omitted from
As best shown in
The side wall 22 is provided with at least one air inlet orifice 26 extending between outside the side wall 22 and the internal space 24. The inlet orifice 26 is preferably oriented so as to face the main flow of air. The illustrated support boss 20 also comprises at least one air outlet orifice 28 made through an opposite side of the side wall 22. This outlet orifice 28 is provided to reduce the wake downstream the support boss 20 and to equalize the pressure around the support boss 20 so as to maintain the efficiency of the cooling orifices 16b, 16b′ made through the wall 16a behind the support boss 20.
The bottom wall 23 comprises a plurality of air outlet orifices 30 extending between the internal space 24 and the interior of the combustor 16. Some of these orifices 30 may be located in the air inlet orifice 26. In use, air enters the support boss 20 through the inlet orifice 26 and some of it escapes through the smaller outlet orifice 28, if provided. Air also escapes through the orifices 30. This way, a cooling path is created to lower the temperature of the support boss 20 and the surrounding parts.
The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. For example, the shape of the combustor 16 and the support boss 20 thereof can be different than what is shown in FIGS. 2 to 4. Although the support boss 20 is shown as being circular, other shapes are possible. The use of a heat shield is optional and depends on the design of the combustor 16. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.
