Flange cavity isolation with discourager seal for reducing flange thermal gradients
Publication Date: 2016-Jun-16
The IP.com Prior Art Database
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Flange cavity isolation with discourager seal for reducing flange thermal gradients Background:
At least some known gas turbine engines, such as turbofan engines, include a fan, a core engine, and a power turbine. The core engine includes at least one compressor, a combustor, and a high-pressure turbine coupled together in a serial flow relationship. At least some known gas turbine engines extract a portion of compressed air from the compressor as bleed air. The bleed air is extracted to perform one or more functions such as, but not limited to, cooling hot gas path components, deicing, passenger cabin pressurization, and cross-starting another turbine engine.
The compressor and the combustor each include a case, which are typically coupled together in a bolted flange connection. When extracting bleed air from the compressor, the bleed air is channeled radially outward towards the case of the combustor. More specifically, the bleed air is channeled into and swirls circumferentially within a cavity defined between the case of the combustor and a circumferentially-extending support structure (i.e., a wishbone structure) before being extracted through the case. The bleed air extracted from the compressor is comparatively hot relative to fluid positioned on a radially outer side of the case. As such, a thermal gradient is formed across the case during operation of the turbine engine. The thermal gradient forms thermally driven stresses within the turbine engine, which can reduce the service life of and cause cracking in the bolted flange connection, for example.
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The system described herein is for reducing the formation of thermal gradients in the bolted flange connection located between the compressor and combustor of a turbine engine. More specifically, the system described herein includes a discourager seal positioned within the cavity defined between the case of the combustor and the wishbone. The discourager seal is positioned such that the cavity is divided into a main cavity and an isolated flange cavity, and such that the hot bleed air is restricted from freely flowing into the isolated flange cavity. Rather, the discourager seal facilitates reducing high-velocity circumferential swirl of bleed air flowing across the discourager seal relative to the bleed air flowing within the main cavity. As such, the isolated flange cavity is not completely sealed from the main cavity. This allows for pressure equalization across the discourager seal while reducing exposure to the high velocity flow.
 As used herein, the terms "axial" and "axially" refer to directions and orientations that extend substantially parallel to a centerline of the turbine engine. Moreover, the terms "radial" and "...