Patent Application
20090053037
The invention relates in general to turbine engines and, more particularly, to turbine vanes.
A plurality of vanes 10 are arranged in an annular array in the turbine section of the engine to form a row of vanes. When installed, the circumferential end 16 of each vane platform 14 abuts a circumferential end 16 of an adjacent vane platform 14, as shown in
During engine operation, high pressure coolant can be supplied to the platforms 14. The seam 22 presents a potential leak path for the coolant. Despite efforts to seal the seam 22, a portion of the coolant inevitably leaks through the seam 22 and enters the turbine gas path. While providing some cooling benefit to the abutting portions of the platforms 14, such leakage flow through the seam 22 is not well controlled or optimized, resulting in excessive leakage in an area that requires relatively little cooling. Thus, there is a need for a turbine vane system that can make productive use of the leakage flow through the seam between adjacent vanes.
Aspects of the invention are directed to a turbine vane. The vane includes an airfoil that has a first end region and a second end region. The airfoil also has a pressure side and a suction side. Further, the airfoil has a leading edge, a trailing edge, and an airfoil mean line that extends from the leading edge to the trailing edge.
The vane includes a first platform that is unitary with the airfoil. The first platform transitions into the airfoil in the first end region. The first platform is located substantially entirely on either the pressure side or the suction side of the airfoil. The first platform extends substantially circumferentially from the airfoil to a circumferential side. The circumferential side is contoured to engage another airfoil. For example, the circumferential side can be contoured to substantially matingly engage the outer peripheral surface of another airfoil.
In one embodiment, the first platform can be located substantially entirely on the pressure side of the airfoil. In such case, the circumferential side can be contoured to engage the suction side of another airfoil. Alternatively, the first platform can be located substantially entirely on the suction side of the airfoil, and the circumferential side of the first platform can be contoured to engage the pressure side of another airfoil.
The turbine vane can further include a second platform unitary with the airfoil. The second platform can transition into the airfoil in the second end region. The second platform can be located substantially entirely on either the pressure side or the suction side of the airfoil. In one embodiment, the first and second platforms can be located on the same side of the airfoil. From the airfoil, the second platform can extend substantially circumferentially to a circumferential side that is contoured to engage another airfoil.
In one embodiment, the first platform does not substantially extend beyond a boundary defined by an imaginary extrapolation of the airfoil mean line beyond the airfoil. In another embodiment, the first platform does not substantially extend beyond a boundary defined by an imaginary axial line extending from the leading edge of the airfoil and an imaginary axial line extending from the trailing edge of the airfoil.
The outer peripheral surface of the airfoil on the opposite one of the pressure side and the suction side of the airfoil from the first platform can be exposed in the first end region. Alternatively, the first platform can further include a platform lip that extends in the first end region about the opposite one of the pressure side and the suction side of the airfoil from the first platform.
Aspects of the invention also concern a turbine vane system. The system includes a first turbine vane and a second turbine vane. The first turbine vane includes a first airfoil with a unitary first outer platform. The first airfoil has an outer region, an inner end region, an outer peripheral surface, a pressure side, a suction side, a leading edge, a trailing edge, and an airfoil mean line that extends from the leading edge to the trailing edge. The first outer platform transitions into the first airfoil in the outer end region. The first outer platform is located substantially entirely on either the pressure side or the suction side of the first airfoil.
The second turbine vane includes a second airfoil with a unitary second outer platform. The second airfoil has an outer end region, an inner end region, a pressure side, a suction side, a leading edge, a trailing edge, and an airfoil mean line that extends from the leading edge to the trailing edge. The second outer platform transitions into the second airfoil in the outer end region. The second outer platform is located substantially entirely on the same one of the pressure side and the suction side of the second airfoil as the first outer platform relative to the first airfoil of the first turbine vane. The second outer platform extends substantially circumferentially from the second airfoil to a circumferential side, which is contoured to engage at least a portion of the side of the first airfoil opposite the first outer platform. For instance, the circumferential side can be contoured to substantially matingly engage at least a portion of the outer peripheral surface of the first airfoil in the outer end region.
The first vane is positioned substantially adjacent the second vane such that the outer end region of the first airfoil is substantially cooperatively enclosed by the first outer platform and the circumferential end of the second outer platform. A seam is formed between the substantially adjacent portions of the first and second vanes. The system can further include a seal operatively positioned along at least a portion of the seam. The seam includes a cooling gap that extends proximate the side of the first airfoil that is opposite the first outer platform. The system also can include a coolant supplied to the outer platform. At least a portion of the coolant can flow through the cooling gap such that the interface between the circumferential end of the second outer platform and the first airfoil can be cooled.
The first outer platform can be located substantially entirely on the pressure side of the first airfoil, and the circumferential side of the second outer platform can be contoured to engage the suction side of the first airfoil. Alternatively, the first outer platform can be located substantially entirely on the suction side of the first airfoil, and the circumferential side of the second outer platform can be contoured to engage the pressure side of the first airfoil.
The first outer platform can include a platform lip, which can extend in the outer end region of the airfoil and about the opposite one of the pressure side and the suction side of the airfoil from the first platform. By providing such a lip, the cooling gap can be formed in part between the platform lip of the first outer platform and the circumferential end of the second outer platform. In one embodiment, the outer peripheral surface of the first airfoil on the opposite one of the pressure side and the suction side of the first airfoil from the first outer platform can be exposed in the outer end region. As a result, the cooling gap can be formed in part between the outer peripheral surface of the first airfoil and the circumferential end of the second outer platform.
In one embodiment, the first outer platform does not extend substantially beyond a boundary defined by an imaginary extrapolation of the mean line beyond the first airfoil. In another embodiment, the first outer platform does not extend substantially beyond a boundary defined by an imaginary axial line extending from the leading edge of the first airfoil and an imaginary axial line extending from the trailing edge of the first airfoil.
Aspects of the present invention are directed to a vane system that can take advantage of the platform seam coolant leakage flow, which would otherwise be wasted in prior turbine vane systems. Aspects of the present invention involve a relocation of the seam to a location proximate the airfoil so that leakage flow therethrough can be used to cool the transition region between the airfoil and the platforms. Embodiments of the invention will be explained in the context of several possible vane configurations, but the detailed description is intended only as exemplary. Embodiments of the invention are shown in
The turbine vane 10 can also include an inner platform 52 and an outer platform 54. The inner and outer platforms 52, 54 are formed with the airfoil 32 so as to be a single piece, that is, as a unitary construction. The inner platform 52 can transition into the airfoil 32 at the inner end region 44 of the airfoil 32. Similarly, the outer platform 54 can transition into the airfoil 32 at the outer end region 40.
According to aspects of the invention, one or both of the inner and outer platforms 52, 54 can be located substantially entirely on one of the pressure side 36 or the suction side 38 of the airfoil 32.
From the suction side 38 the airfoil 32, each platform 52, 54 can extend circumferentially to a circumferential side 56. At least a portion of the circumferential side 56 can be contoured for engagement with a portion of a neighboring airfoil. In the embodiment shown in
The platforms 52, 54 can also extend from the airfoil 32 to an axial forward side 58 and an axial rearward side 60. The airfoil 32 can be located substantially centrally between the axial forward side 58 and the axial rearward side 60 of each platform. The terms “axial,” “circumferential” and variants thereof are intended to mean relative to the axis of the turbine when the vane 30 is installed in its operational position. The configuration of the inner platform 52 may or may not be substantially identical to the configuration of the outer platform 54.
Generally, the inner and outer platforms 52, 54 are formed on the suction side 38 of the airfoil 32 so as not to extend beyond the leading edge 46 and the trailing edge 48 of the airfoil 32. In one embodiment, the inner and outer platforms 52, 54 can be located substantially entirely on the suction side 38 of the airfoil 32 such that a substantial majority of each platform 52, 54 does not extend beyond a boundary defined by an imaginary extrapolation 62 of the airfoil mean line 50 beyond the outer peripheral surface 34 of the airfoil 32. Alternatively, the inner and outer platforms 52, 54 can be located substantially entirely on the suction side 38 of the airfoil 32 such that a substantial majority of each platform does not substantially extend beyond a boundary defined by an imaginary axial line 64 extending from the leading edge 46 of the airfoil 32 and an imaginary axial line 66 extending from the trailing edge 48 of the airfoil 32. However, as shown in
Aspects of the invention are not limited to embodiments in which the platforms 52, 54 are formed on the suction side 38 of the airfoil 32. For instance, as shown in
Further, aspects of the invention are not limited to embodiments in which the side of the airfoil opposite the unitary platform is exposed in the end region. For instance,
In any given row of vanes, one or more of the vanes can be constructed in accordance with aspects of the invention. The vanes can be connected to a vane carrier (not shown) or other stationary support structure (not shown) in the turbine section.
It should be noted that the circumferential side 56 of the platform 52 associated with the second vane 72 can engage the airfoil 32 of the first vane 70 in any of a number of ways. For instance, the circumferential end 56 can engage the outer peripheral surface 34 of the airfoil 32 in the end region 40 of the pressure side 36 of the vane 32. Alternatively or in addition, at least a portion of the circumferential end 56 can extend under the platform 52 associated with the first vane 70 so as to engage at least a portion of the inner end (not shown) of the first airfoil 32. For a vane 10 configured as shown in
During engine operation, a high pressure coolant 82, such as air, can be supplied to the platforms 52, 54. A portion of the coolant 82 can leak through the cooling gap 80 and enter the turbine gas path 84. Because the seam 78 is located proximate the airfoil 32, the coolant leakage can cool the transition region 86 between the airfoil 32 and the platforms 52, 54, particularly when the cooling gap 80 is formed in part by the airfoil 32. Such cooling benefits can also be enjoyed when the vane 10 includes a platform lip 68, as shown in
To further focus the leakage toward the airfoil, one or more seals 88 can be operatively positioned along those portions of the seam 78 formed by the abutting portions of the platforms 52, 54 of the first vane 70 and the platforms 52, 54 of the second vane 72. The seals 88 can be any suitable seal, such as flat plate seals, riffle seals, etc. Thus, it will be appreciated that the seals 88 can be used to direct the leakage flow through those portions of the seam 78 that are proximate the airfoil 32.
Aside from the cooling effect, aspects of the invention can result in a number of additional benefits. For example, aspects of the invention can result in a potential increase in engine efficiency as well as component life. Further, the unitary platform and airfoil can facilitate assembly and can reduce the number of unique pieces to install. Further, by providing the platform on one side, less sealing is needed and a more controlled leakage flow can be achieved.
The foregoing description is provided in the context of various embodiments of a turbine vane in accordance with aspects of the invention. It will be understood that aspects of the invention can be applied to any of a number of vane configurations. For instance, a vane can include multiple airfoils extending between the inner and outer platform. Aspects of the invention can be applied to such vanes, though not all of the airfoils will benefit from the leakage flow through the seam. Thus, it will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the invention as defined in the following claims.
