Patent Application
20140238027
The present disclosure relates to gas turbine engines, and more particularly to an exhaust duct therefor.
Gas turbine engines, such as those which power modern military aircraft, include a compressor to pressurize a supply of air, a combustor to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine to extract energy from the resultant combustion gases and generate thrust. Downstream of the turbine, an augmentor, or “afterburner”, is operable to selectively increase the thrust. The increase in thrust is produced when oxygen contained within the exhaust gases of the engine downstream of the turbine is injected with fuel and burned to generate a second combustion.
Due in part to the harsh environment of the second combustion, a liner assembly is disposed between the exhaust gas and the exhaust duct. These may be of single or double walled construction, with a hot sheet and a cold sheet. Cooling air typically extracted from the compressor is flowed between the liner assembly and exhaust duct then discharged through the liner assembly.
The attachment of the hot sheet and the cold sheet is typically accomplished with Z-resilient member stiffeners. Although effective, transverse thermal gradient in which the difference in temperature between the hot and cold sheets may develop stress in the Z-resilient members. Also, each Z-resilient member may require unique and relatively expensive manufacturing tooling.
A stiffener for a liner assembly of a gas turbine engine according to one disclosed non-limiting embodiment of the present disclosure includes a first resilient member; and a second resilient member arranged on said first resilient member at a substantially ninety (90) degree orientation.
In a further embodiment of the foregoing embodiment, the first resilient member and said second resilient member are formed from a single cross-section-shaped piece.
In a further embodiment of any of the foregoing embodiments, the first resilient member and said second resilient member are generally racetrack shaped.
In a further embodiment of any of the foregoing embodiments, the first resilient member and said second resilient member are generally oval.
In a further embodiment of any of the foregoing embodiments, the first resilient member and said second resilient member are generally circular.
A liner assembly for a gas turbine engine according to another disclosed non-limiting embodiment of the present disclosure includes a cold sheet, a hot sheet, and a multiple of stiffeners between said cold sheet and said hot sheet, at least one of said multiple of stiffeners includes a first resilient member arranged on a second resilient member.
In a further embodiment of the foregoing embodiment, the first resilient member and said second resilient member are oriented at a substantially ninety (90) degrees.
In a further embodiment of any of the foregoing embodiments, the cold sheet is corrugated.
In a further embodiment of any of the foregoing embodiments, the hot sheet and said cold sheet are axisymmetric in cross-section.
In a further embodiment of any of the foregoing embodiments, the hot sheet and said cold sheet are non-axisymmetric in cross-section.
In a further embodiment of any of the foregoing embodiments, the hot sheet and said cold sheet are oval in cross-section.
In a further embodiment of any of the foregoing embodiments, the hot sheet and said cold sheet are rectilinear in cross-section.
In a further embodiment of any of the foregoing embodiments, the hot sheet and said cold sheet define a serpentine duct.
In a further embodiment of any of the foregoing embodiments, the hot sheet and said cold sheet terminate in a nozzle with a convergent-divergent nozzle.
In a further embodiment of any of the foregoing embodiments, the hot sheet and said cold sheet terminate in a nozzle with a two-dimensional non-axisymmetric nozzle.
In a further embodiment of any of the foregoing embodiments, the multiple of stiffeners are non-uniformly distributed between said hot sheet and said cold sheet.
In a further embodiment of any of the foregoing embodiments, a first of said multiple of stiffeners defines a first spring rate and a second of said multiple of stiffeners defines a second spring rate, said first spring rate different than said second spring rate.
In a further embodiment of any of the foregoing embodiments, the first resilient member is brazed to said hot sheet and said second resilient member is brazed to said cold sheet.
In a further embodiment of any of the foregoing embodiments, the multiple of stiffeners provide thermal freedom between said hot sheet and said cold sheet.
In a further embodiment of any of the foregoing embodiments, the liner assembly includes a multiple of hangers attached to said hot sheet.
Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows:
An outer static structure 36 and an inner static structure 38 define a generally annular secondary airflow path 40 around a core primary airflow path 42. Various structure and modules may define the outer static structure 36 and the inner static structure 38 which essentially define an exoskeleton to support the core engine therein.
Air that enters the fan 22 is divided between a primary airflow through the primary airflow path 42 and a secondary airflow through the secondary airflow path 40. The core flow passes through the combustor 26, the turbine 28, then the augmentor 30 where fuel may be selectively injected and burned to generate additional thrust through the nozzle 34. It should be appreciated that additional airflow streams such as third stream airflow typical of variable cycle engine architectures may additionally be sourced from the fan 22.
The secondary airflow may be utilized for a multiple of purposes to include, for example, cooling and pressurization. The secondary airflow as defined herein is any airflow different from the primary combustion gas exhaust primary airflow. The secondary airflow may ultimately be at least partially injected into the primary airflow adjacent to the exhaust duct 32 and the nozzle 34.
With reference to
With reference to
The liner assembly 46 generally includes a cold sheet 50 separated from a hot sheet 52 by a plurality of stiffeners 54 (also illustrated in
With reference to
The first resilient member 60 is brazed to the cold sheet 50 and the second resilient member 62 is brazed to the hot sheet 52. It should be understood that other attachments such as welding, rivets or others will also benefit herefrom. The plurality of stiffeners 54 to provide thermal freedom between the cold sheet 50 and the hot sheet 52 in the radial, (
During engine operation, the cold sheet 50 receives relatively large pressure loads and deflections, while the hot sheet 52 receives relatively small pressure loads and deflections and thereby better retains heat resistant coatings. The plurality of stiffeners 54 provides stiffness to the liner assembly 46 yet operate as springs to accommodates movement through thermal deflections between the cold sheet 50 and the hot sheet 52. Non-axisymmetric exhaust duct s may be particularly susceptible to thermal deflection in the relatively flat regions (
The spring rate of the stiffeners 54 may be readily adjusted through, for example, material sheet thickness, height and width of the resilient members 60, 62. The spacing and array arrangement of the multiple of stiffeners 54 (
The multiple of stiffeners 54 thereby provide thermal compliance in all directions between the cold sheet 50 and the hot sheet 52 of the liner assembly irrespective of exhaust duct architecture. The thermal compliance also facilitates heat resistant coating retention on the hot sheet thereby reducing maintenance requirements. Moreover, the stiffeners 54 are relatively uncomplicated and inexpensive to manufacture compared to related art Z-resilient members.
It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom.
Although the different non-limiting embodiments have specific illustrated components, the embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.
Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure.
The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.
