1. Technical Field
The disclosure generally relates to gas turbine engines.
2. Description of the Related Art
Various gas turbine engine components, such as turbine blades, can experience platform distress due to high platform metal temperatures and low backside heat transfer. By way of example, platform distress can include creep (or deformation), thermo-mechanical fatigue (TMF), and oxidation in areas that are difficult to cool. Notably, blade platforms oftentimes rely on filmholes that route cooling air to the heated surfaces of the platforms.
Gas turbine engine systems involving baffle assemblies are provided. In this regard, an exemplary embodiment of a baffle assembly for a gas turbine engine comprises: a cooling plenum defining a cooling air path; and a baffle sized and shaped to extend between surfaces of the cooling plenum such that a cooling air path of reduced cross-section is formed between the baffle and the surfaces, the baffle being operative to increase a flow rate of cooling air as the cooling air directed to the cooling air path is redirected through the cooling air path of reduced cross-section.
An exemplary embodiment of a gas turbine engine assembly comprises: a turbine disk; and a blade assembly having a first blade, a second blade and a baffle, the first blade and the second blade being operative to attach to the turbine disk; the first blade having a first inner diameter platform with an outer diameter side and an inner diameter side; the second blade having a second inner diameter platform with an outer diameter side and an inner diameter side; the baffle operative to form a cooling air path between the baffle and respective inner diameter sides of the first platform and the second platform.
An exemplary embodiment of a gas turbine engine comprises: a compressor; a turbine operative to drive the compressor; a cooling plenum defining a cooling air path for cooling the turbine; and a baffle sized and shaped to extend between surfaces of the cooling plenum such that a cooling air path of reduced cross-section is formed between the baffle and the surfaces, the baffle being operative to increase a flow rate of cooling air as the cooling air directed to the cooling air path is redirected through the cooling air path of reduced cross-section.
Other systems, methods, features and/or advantages of this disclosure will be or may become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features and/or advantages be included within this description and be within the scope of the present disclosure.
Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
Gas turbine engine systems involving baffle assemblies are provided, several exemplary embodiments of which will be described in detail. In various embodiments, a baffle (e.g., a removable, free-floating baffle) is utilized to reduce the effective cross-sectional area through which cooling air flows, such as a cooling plenum associated with one or more vanes, blades and/or blade outer air seals. Notably, blade platforms are structures (typically integrated with one or more blade airfoils) that define the inner diameter confines of the gas path that directs gas across the blade airfoils. By reducing the size of the cooling plenum that defines a cooling air path on the non-gas path sides of the inner diameter platforms, flow velocity of cooling air in a vicinity of the blade platform is increased. This tends to increase heat transfer and decrease platform temperature, thereby potentially decreasing platform distress.
In this regard,
An exemplary embodiment of a baffle assembly is depicted in
Baffle 202 is formed of temperature resistant material (e.g., cobalt sheet metal) and is sized and shaped to form a cooling air path of reduced cross-section 250 (
As shown in
Cooling air path 250 formed by baffle 202 increases a velocity of cooling air flowing adjacent the inner diameter sides of the platforms 210, 226. Notably, the flow of cooing air enters near the leading edge of the blades and exits via film cooling holes (e.g., holes 253, 255) of the platforms.
This increase in velocity tends to increase the heat transfer coefficients, decrease platform temperatures, and reduce platform distress, which may otherwise be caused due to high temperatures. By way of example, in conventional blade platforms, without the presence of a baffle, the low backside heat transfer can be at a rate of approximately 50 BTU/ft2/Hr/° F. and create an approximate temperature of 2050 degrees Fahrenheit on the inner diameter side of the blade platform. Such high platform temperatures can lead to platform distress. Notably, even though cooling air is typically used, that cooling air is generally routed through the relatively large plenum created between the blade platforms and the disk rim, which can be approximately 0.50 inches in conventional turbines.
However, the heat transfer in the representative embodiment of
Another exemplary embodiment of a baffle assembly is depicted in
In this embodiment, baffle 306 rides on rails 318, 320 that are located on the non-gas path sides 322, 324 of the blades. Pin fins also are provided on the non-gas path sides of the platforms of the blades. Specifically, platform 310 includes multiple pin fins (e.g., pin fin 326), and platform 312 includes multiple pin fins (e.g., pin fin 328).
The pin fins may enhance heat transfer coefficients and further reduce platform temperatures by increasing the surface area of the platforms in a vicinity of the cooling air flows directed by the baffle 306. Additionally, in some embodiments, the pin fins can function as standoffs for structurally supporting and/or positioning the baffle.
It should also be noted that, in some embodiments, a baffle can be sized and shaped to fit relatively loosely against an adjacent blade. As such, the baffle can provide a vibration damping function. Notably, the relatively loose fit enables the baffle to move relative to the blade thereby tending to compensate for vibrations.
Another exemplary embodiment of a baffle assembly is depicted in
In operation, cooling air provided for cooling the blade outer air seal 118 is directed between the baffle 356 and the outer diameter surfaces (e.g., surface 352). Thus, the baffle 356 causes the cooling air to be routed along cooling air path 358, which increases the velocity of the cooling air. In this embodiment, the cooling air enters cooling air path at an end of the blade outer air seal that is opposite that of cooling passage inlet holes (e.g., hole 360) so that the cooling air flows substantially along the length of the blade outer air seal before entering the cooling passage inlet holes.
It should be emphasized that the above-described embodiments are merely possible examples of implementations set forth for a clear understanding of the principles of this disclosure. Many variations and modifications may be made to the above-described embodiments without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the accompanying claims.
The U.S. Government may have an interest in the subject matter of this disclosure as provided for by the terms of contract number N00019-02-C-3003 awarded by the U.S. Navy.