Patent Application
20130167552
The subject matter disclosed herein relates to an exhaust strut and, more particularly, to an exhaust strut for use during at least off design conditions in turbomachinery, such as a power generation turbine.
Generally, a turbomachine, such as a power generation gas turbine engine, includes a turbine section and a diffusion section. The turbine section is configured to generate power and/or electricity from a flow of high temperature fluids and outputs turbine exhaust from a remainder of the high temperature fluids at an aft end thereof. The diffusion section is disposed downstream from the aft end of the turbine section and is fluidly coupled to the turbine section such that the turbine exhaust flows into the diffusion section. Within the diffusion section, the flow of the turbine exhaust is diffused and conditioned for exhaust into the atmosphere.
With increasing demand for flexible turbomachine operation, part load operations become important. At part load, flows from turbine section aft stages entering the diffusion section as exhaust may not be present as shock-less flows and may cause pressure losses. These pressure losses can directly impact turbomachine efficiency and usability at part load.
According to one aspect of the invention, an exhaust strut is provided and includes a body having an airfoil-shaped cross-section defining a lead edge portion and a trailing edge portion opposite the lead edge portion, the lead edge portion and the trailing edge portion being connected by a pressure side and a suction side opposite the pressure side, at least the lead edge portion and respective sections of the pressure side and the suction side proximate to the lead edge portion being formed of shape memory alloy, and a temperature control system operably disposed at the lead edge portion and the respective sections of the pressure side and the suction side proximate to the lead edge portion to modify a temperature of the shape memory alloy.
According to another aspect of the invention, an exhaust strut is provided and includes a body having an airfoil-shaped cross-section defining a lead edge portion and a trailing edge portion opposite the lead edge portion, the lead edge portion and the trailing edge portion being connected by a pressure side and a suction side opposite the pressure side, an external surface of the body being formed of shape memory alloy in strips along the lead edge portion, the trailing edge portion, the pressure side and the suction side, and a temperature control system operably disposed at the external surface of the body to modify a temperature of one or more of the strips of the shape memory alloy.
According to yet another aspect of the invention, a turbomachine is provided and includes a turbine section, a diffusion section disposed downstream from and is fluidly coupled to the turbine section and an exhaust strut disposed in a forward end of the diffusion section. The exhaust strut includes a body having an airfoil-shaped cross-section defining relative to a main flow proceeding through the turbine section and the diffusion section a lead edge portion and a trailing edge portion, the lead edge portion and the trailing edge portion being connected by a pressure side and a suction side, at least the lead edge portion and respective sections of the pressure side and the suction side proximate to the lead edge portion being formed of shape memory alloy and a temperature control system operably disposed at the lead edge portion and the respective sections of the pressure side and the suction side proximate to the lead edge portion to modify a temperature of shape memory alloy.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
In accordance with aspects, shape memory alloy (SMA) is provided to exhaust struts of a turbomachine, such as a gas turbine engine. In general, SMA has a characteristic property by which the SMA is able to remember an original shape thereof when a temperature thereof is changed above/below a characteristic transition temperature. As described herein, this property can be utilized to modify an orientation of an exhaust strut with respect to incoming flow from a turbine section. In particular, the SMA portion of the exhaust strut will be provided with a temperature control system through which secondary flow can be directed during at least part load operation. This secondary flow can be provided from a dedicated source or may be blower air that is otherwise used for cooling the exhaust strut. When the secondary flow is passed through the temperature control system, the SMA temperature may be modified to cause the SMA to shape-change. That is, the SMA can be made to shape-change in response to changes in flow temperatures or any measurable turbine parameter brought about by load changes to thereby permit shock-less entry of incoming flows from the turbine section.
With reference to
With reference to
The pressure side 34 extends between the lead edge portion 32 and the trailing edge portion 33 to define a section 341 of the pressure side that is proximate to the lead edge portion 32. Similarly, the suction side 35 extends between the lead edge portion 32 and the trailing edge portion 33 to define a section 351 of the suction side that is proximate to the lead edge portion 32. In accordance with embodiments, the body 30 may be formed of SMA 400 (see
With reference to
In accordance with embodiments, as shown in
The temperature control system 40 is thus configured to direct a secondary flow toward at least the SMA 400 during at least part load operation of the turbomachine 10. This secondary flow can be provided from a dedicated source or may be blower air that is otherwise used for cooling the exhaust strut 20. Piping 51 (see
With reference back to
With reference back to
In accordance with embodiments, the processing unit 50 may be configured to receive as inputs and thereby sense at least one of a load and/or an operational change of the turbomachine 10. The processing unit 50 could thus control the temperature of the SMA 400 accordingly. Also, to the extent that the SMA 400 may not sufficiently cause a shape-change, it is to be understood that an auxiliary mechanical device may be provided to mechanically change a shape of the exhaust strut 20.
In accordance with still further embodiments and, with reference to
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
