Rope seal for Reducing Post Impingement Air Leakages
Publication Date: 2015-Nov-12
The IP.com Prior Art Database
The invention relates to gas turbine engines Specifically the invention relates to the use of a rope seal to reduce post impingement cooling air leakages between a hanger and a shroud
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Rope seal for Reducing Post-Impingement Air Leakages
The invention relates to gas turbine engines. Specifically, the invention relates to the use of a rope seal to reduce post-impingement cooling air leakages between a hanger and a shroud.
At least some known gas turbine engines include a fan assembly, a core engine, and a power turbine. The core engine includes at least one compressor that provides pressurized air to a combustor where the air is mixed with fuel and ignited for generating hot combustion gases. The combustion gases are channeled through one or more turbines that extract energy therefrom to power the compressor and an aircraft. Specifically, known turbines include a turbine nozzle which channels combustion gases towards a plurality of circumferentially-spaced turbine blades that extend radially outward from a rotor disk that rotates about the centerline axis of the engine.
Known turbines also include a shroud assembly coupled downstream from the turbine nozzle. The shroud assembly circumscribes the turbine rotor and defines an outer boundary for combustion gases flowing through the turbine. At least some known shroud assemblies include a shroud hanger that is coupled to an outer casing of the engine to provide support to a plurality of shrouds positioned adjacent to, and radially outward of, the tips of the turbine blades. In its function as a flowpath component, the shroud segment and assembly must be capable of meeting the design life requirements selected for use in a designed engine operating temperature and pressure environment. To enable current materials to operate effectively as a shroud in the strenuous temperature and pressure conditions as exist in the turbine section flowpath of modern gas turbine engines, it has been a practice to provide cooling air to a radially outer portion of the shroud. At least some known shroud hanger members include a cooling passage that extends
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through a portion of the shroud hanger to enable cooling air to be channeled towards the shrouds. Air is often routed from the compressor through these cooling passages to provide high pressure cooling air in a process known as impingement cooling.
However, as is well known in the art, provision of such cooling air is at the expense of engine efficiency. Therefore, it is desired to conserve use of cooling air by minimizing leakage of cooling air into the flowpath of the engine. For example, cooling air leakage about the edges of a shroud segment can reduce designed efficiency by wasting cooling airflow. After cooling air is used for impingement cooling of a shroud member, it becomes post-impingement air that must exit the shroud chamber. Often this air leaks into the hot gas path through openings between the shroud and its supporting hanger. The amount of leaka...