Patent Application
20190063322
The present disclosure is directed a turbine engine combustor and, more particularly, to a turbine engine combustor wall with a local feature providing more material enabling more complex cooling passages to improve cooling effectiveness and to prevent hot spot propagation.
A turbine engine can include a fan, a compressor, a combustor, and a turbine. The combustor can include an annular bulkhead extending radially between an upstream end of a radial inner combustor wall and an upstream end of a radial outer combustor wall. The inner and the outer combustor walls can each include an impingement cavity extending radially between a support shell and a heat shield. The support shell can include a plurality of impingement apertures, which directs cooling air from a plenum surrounding the combustor into the impingement cavity and against an impingement cavity surface of the heat shield. The heat shield can include a plurality of effusion apertures, which directs the cooling air from the impingement cavity into the combustion chamber for film cooling a combustion chamber surface of the heat shield.
During operation, fuel provided by a plurality of combustor fuel injectors is mixed with compressed gas within the combustion chamber, and the mixture is ignited. Due to varying flow and combustion temperatures within the combustion chamber, the inner and outer combustor walls can be subject to axially and circumferentially varying combustion chamber gas temperatures. Such varying temperatures can cause significant temperature differentials with combustor walls, which can cause combustor wall material fatigue. Under certain conditions, debris, such as, dust, sand, volcanic ash, and siliceous foreign particles, can settle in certain locations on the impingement cavity surface of the combustor heat shield. The debris forms a glassy melt of calcium-magnesium aluminosilicate (CMAS) deposit that can interact with the heat shield and forms a boundary layer on the cavity surface. The deposit diminishes the heat transfer capacity of the heat shield in that hot spot location. Hot spots can form at locations along the walls that ultimately burn through the walls and diminish cooling effectiveness resulting in wall deterioration.
In accordance with the present disclosure, there is provided a combustor wall for a turbine engine with an axial centerline comprising a combustor support shell comprising a plurality of impingement apertures; a combustor heat shield comprising a plurality of effusion apertures fluidly coupled with the plurality of impingement apertures; and at least one shaped pad formed in the combustor heat shield, the at least one shaped pad extending through a cutout in the combustor support shell.
In another exemplary embodiment the shaped pad comprises an additional thickness to the heat shield over a predetermined area, at a location corresponding to a hot spot.
In another exemplary embodiment the hot spot comprises a location on the heat shield susceptible to a debris deposit, higher temperatures and subsequent loss of material due to thermal and chemical degradation.
In another exemplary embodiment the hot spot is located on the heat shield downstream of at least one fuel injector assembly.
In another exemplary embodiment the shaped pad comprises an extension from an impingement cavity surface of the heat shield.
In another exemplary embodiment the cutout comprises a shape matching the shaped pad, the cutout includes a larger dimension configured to allow the shaped pad to pass through the support shell.
In another exemplary embodiment the hot spots are located in-line and a half of a combustor dome height downstream of fuel injector assemblies.
In accordance with the present disclosure, there is provided a turbine engine combustor comprising a hybrid double wall, the hybrid double wall comprising a heat shield having a shaped pad extending through a support shell, the shaped pad being located at a hot spot on the heat shield.
In another exemplary embodiment the shaped pad is selected from the group consisting of a triangle shape, a trapezoid shape, a rectangle shape and a hot spot shape determined by analysis or testing.
In another exemplary embodiment the shaped pad comprises at least one effusion aperture configured to conduct cooling fluid across the thickness of the heat shield.
In another exemplary embodiment the shaped pad is shaped similar to the shape of the hot spot.
In another exemplary embodiment the hybrid double wall further comprises a combustor support shell comprising a plurality of impingement apertures; a combustor heat shield comprising a plurality of effusion apertures fluidly coupled with the plurality of impingement apertures via an impingement cavity between the combustor support shell and the combustor heat shield; the shaped pad formed in the heat shield includes effusion apertures fluidly coupled from a combustor plenum through the heat shield and fluidly coupled to a combustion chamber.
In another exemplary embodiment the hybrid double wall is configured for a cooling fluid to flow from the combustor plenum through the impingement apertures into the impingement cavity, and configured for the cooling fluid to flow from the impingement cavity through the effusion apertures of the heat shield into the combustion chamber; and at least one effusion aperture formed in the shaped portion fluidly coupled from the impingement cavity through the heat shield to the combustion chamber.
In accordance with the present disclosure, there is provided a process of protecting a turbine engine combustor heat shield from hot spot degradation. The process comprises forming a shaped pad in the heat shield; locating the shaped pad proximate the hot spot on the heat shield; and forming at least one effusion aperture in the shaped pad, the at least one effusion aperture configured to conduct a cooling fluid through the heat shield.
In another exemplary embodiment the shaped pad through a support shell of the combustor.
In another exemplary embodiment the shaped pad comprises shaping the shaped pad into a shape similar to a shape of the hot spot.
In another exemplary embodiment the process further comprises forming a combustor support shell comprising a plurality of impingement apertures; fluidly coupling the combustor heat shield comprising additional effusion apertures with the plurality of impingement apertures via an impingement cavity between the combustor support shell and the combustor heat shield; fluidly coupling a combustor plenum with a combustion chamber by flowing the cooling fluid through the at least one effusion aperture formed in the shaped pad.
In another exemplary embodiment the process further comprises flowing the cooling fluid from the combustor plenum through the impingement apertures into the impingement cavity, and flowing the cooling fluid from the impingement cavity through the additional effusion apertures of the heat shield into the combustion chamber; and flowing the cooling fluid from the impingement cavity through the at least one effusion aperture formed in the shaped portion of the heat shield to the combustion chamber.
In another exemplary embodiment the forming the shaped pad comprises determining the shape hot spot through use of computer modeling or testing.
Other details of the hybrid floatwall cooling features are set forth in the following detailed description and the accompanying drawings wherein like reference numerals depict like elements.
The first combustor wall 16 and the second combustor wall 20 can each include a combustor support shell 30 and a combustor heat shield 32. The support shell 30 extends axially between the upstream end 14, 18 and a downstream end 34, 36. The support shell 30 extends circumferentially around the axial centerline 24, which provides the support shell 30 with an annular cross-sectional geometry. Referring to
Referring to
The impingement apertures (e.g., the apertures 44) extend radially through the support shell 30 between the combustor plenum surface 38 and the first impingement cavity surface 40. Each of the impingement apertures (e.g., the apertures 44) has an axis 48 that is angularly offset from first impingement cavity surface 40, for example, by an angle θ of about ninety degrees. Each of the impingement apertures (e.g., the apertures 44) can have a circular cross-sectional geometry with a second diameter 50, which is substantially (e.g., at least five to twenty times) smaller than the first diameter 46.
Referring to
Referring again to
Referring to
The effusion apertures (e.g., the apertures 96) extend radially through the heat shield 32 between the second impingement cavity surface 86 and the combustion chamber surface 88. Each of the effusion apertures (e.g., the apertures 96) has an axis 100 that is angularly offset from the combustion chamber surface 88, for example, by an angle α of between about fifteen and about thirty degrees (e.g., about 25°). Each of the effusion apertures (e.g., the apertures 96) can have a circular cross-sectional geometry with a fourth diameter 102, which is substantially (e.g., at least five to twenty times) smaller than the third diameter 98. The fourth diameter 102 of some or all of the effusion apertures can be greater than, less than or equal to the second diameter 50.
Referring to
In some embodiments, for example as illustrated in
Referring to
The hybrid double wall 116 includes a support shell 30 and heat shield 32 with an impingement cavity 138 between for cooling fluid to flow. The cooling fluid flows from the combustion plenum 144 through impingement apertures 44 of the support shell 30 into the impingement cavity 138. The cooling fluid 120 flows from the impingement cavity 138 through the effusion apertures 96 of the heat shield 32 into the combustion chamber 142. The hybrid double wall 116 also includes the shaped pad 110 formed in the heat shield 32. The shaped pad 110 includes effusion apertures 96 configured to flow cooling fluid from the combustor plenum 144 through the heat shield 32 and into the combustion chamber 142. In an exemplary embodiment, effusion aperture 96 can be provided in the shaped portion 110 and configured to flow cooling fluid 120 from the impingement cavity 138 through the heat shield 32 into the combustion chamber 142.
The hot spots 112 are locations on the heat shield susceptible to higher temperatures and subsequent loss of material due to thermal and chemical degradation. The hot spot 112 can be found downstream of the fuel injector assemblies 22. In an exemplary embodiment, the hot spots 112 can be located in-line and about a half of a combustor dome height downstream of the fuel injector assemblies 22. The hot spot 112 in the heat shield 32 can lead to wall failure resulting in a blowout, that is, a larger hole or aperture 96 in the heat shield 32. The hole/larger aperture 96 changes the cooling flow characteristics in the hot spot 112 location. The changes in cooling flow characteristics can lead to less cooling and higher temperatures at the hot spot 112. The hot spot 112 can increase in size as the changes in cooling characteristics cascades into ever decreasing cooling capacity.
The shaped pad 110 comprising greater thickness and material at the location of the hot spot 112, allows for greater durability. The thermal and chemical degradation takes a longer period of time to create the initial wall failure.
The shaped pad 110 is depicted as a triangle shape but it is contemplated that any shape can be utilized, such as, triangle, trapezoid, rectangle and the like, depending on the hot spot 112 location. In an exemplary embodiment, if the shaped pad 110 is configured as a triangle, the height of the triangle can be about one quarter of a combustor dome height. In an exemplary embodiment, the location, size and shape of the shaped pad 110 can be determined by testing in the laboratory as well as through computer modeling. For example, a computer model can determine an estimate of the location, size and shape of the hot spot 112. Then, laboratory testing in a test rig can be performed to gain empirical data for location, size and shape of the hot spot 112.
The shaped pad 110 can include the effusion apertures 96 that conduct cooling fluid flow 120 across the heat shield 32. The effusion apertures 96 in the heat shield 32 and impingement apertures 44 in the support shell 30 can be configured to maintain the proper cooling flow proportions through the heat shield 32 and support shell 30. The pressure drop between the airflow through the impingement apertures 44 across the support wall 30 and the airflow through effusion apertures 96 across the heat shield 32 can be split and defined as a ratio. The pressure drop split can be 100 to 0 for cooling flow through the heat shield at the shaped pad 110. The pressure drop split can be 50/50 to 80/20 near other portions of the support shell 30 and heat shield 32 proximate the shaped pad 110.
Cooling air 120 flowing through the impingement apertures 44 in the support shell 30 is subject to a cooling air first pressure drop between the combustor plenum surface 38 and the first impingement cavity surface 40. The magnitude of the first pressure drop is influenced by the number and/or diameter of the impingement apertures 44. Cooling air 120 flowing through the effusion apertures 96 in the heat shield 32 is subject to a cooling air second pressure drop between the second impingement cavity surface 86 and the combustion chamber surface 88. The magnitude of the second pressure drop is influenced by the number and/or diameter of the effusion apertures 96. In some embodiments, in the hybrid double wall system 116 the numbers and/or effective flow areas of the impingement and effusion apertures 44, 96 are selected such that a ratio of the first pressure drop to the second pressure drop is between about 1 to 1 (50:50) and about 1 to 2 (80:20). For example, if the liner has 3% P3 pressure loss, for an 80/20 split, the heat shield 32 would have 0.6% compressor discharge pressure loss across it and the impingement sheet would have the remainder 2.4%.
During operation of the combustor 10 of
The thicker wall found in the location of the shaped pad 110 provides more heat shield wall material that has to be burned through.
The portion of the shaped pad 110 of the heat shield 32 is designed to take 100% of the liner pressure loss. With the shaped pad 110 taking 100% of the pressure loss, there is potential that the local hot spots 112 will not propagate to adjacent panels in the combustor 10. The shaped pad 110 will maintain the local cooling effectiveness, and prevent deterioration of the local cooling effectiveness.
The thicker material at the shaped pad 110 can enable more complex cooling passages and improve cooling effectiveness.
Implementation of the hybrid double wall 116 with strategic shaped pads 110 in the heat shield 32 can provide longer life for the heat shield 32. The longer life can be attained through slowing or stopping the panel burn-though cascading to the support shell 30 near the hot spots 112.
The shaped pads 110 cooling flow also makes the heat shield 32 insensitive to debris, sand, dirt and the like, plugging the cooling apertures 44, 96. The shaped pads 110 eliminate the impingement cavity 138 between the heat shield and the support shell where sand and debris can become entrained.
The implementation of the shaped pad 110 can allow for the utilization of a hybrid double wall or even a single wall design. This simplifies the hoop stress.
There has been provided a hybrid floatwall cooling feature. While the hybrid floatwall cooling feature has been described in the context of specific embodiments thereof, other unforeseen alternatives, modifications, and variations may become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications, and variations which fall within the broad scope of the appended claims.
