Patent Application
20120045318
The subject matter disclosed herein relates to gas turbines. More particularly, the subject matter relates a guide vane in the gas turbine.
In a gas turbine, a compressor adds kinetic energy to a fluid, such as air, by increasing the fluid's tangential momentum. The kinetic energy from the compressor and thermal energy from the combustor is conveyed by a fluid, often air, to a turbine where the energy of the fluid is converted to mechanical energy. Several factors influence the efficiency of adding kinetic energy in the compressor. These factors may include air distribution within the compressor, pressure rise across the compressor, and loss sources in the compressor. One embodiment is a guide vane in the compressor which influences the distribution and magnitude of airflow into the compressor. The guide vane may be designed for high efficiency at a selected condition for the turbine, such as full load, high power output and/or fuel usage. The guide vane controls the air flow in the compressor, which determines the entitlement on kinetic energy that can be supplied to the rest of the gas turbine system. However, when operating at lower loads and reduced power output, the air flow distribution and aerodynamic loading from the guide vane causes less efficient gas turbine performance.
According to one aspect of the invention, an air flow control apparatus includes a guide vane to be positioned between an air inlet and a compressor rotor of a turbomachine. Further, the guide vane includes a geometry configured to control an air flow incidence on the rotor, the guide vane further having a substantially constant aspect ratio. In addition, a body of the guide vane includes a shape memory material configured to change a geometry of the guide vane in response to energy provided by a power source.
According to another aspect of the invention, a method for controlling air flow in a compressor includes flowing air from an inlet toward a guide vane and applying an energy to a shape memory material in the guide vane to change a geometry of the guide vane to control a distribution of air flow toward a rotor.
According to yet another aspect of the invention, a turbine compressor includes an air inlet, a rotor positioned downstream of the air inlet, and a guide vane positioned between the air inlet and the rotor, the guide vane comprising a shape memory material. The compressor also includes a power source coupled to the shape memory material to cause a change of a guide vane geometry.
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.
A plurality of inlet guide vanes 104 (one shown) are disposed about the centerline axis 102 in front of one or more compressors 106. As depicted, the compressor 106 includes an inner hub 108 and outer casing 110, providing a flow path for air toward one or more combustors. The inlet guide vane 104 directs air flow from an inlet region 112, as indicated by arrow 114, downstream toward a first stage of the compressor 106. In an aspect, the compressor 106 includes a plurality of stages. A first stage of the plurality of stages includes a rotor 116 and stator 118. Similarly, a second stage includes a rotor 120 and stator 122 and a third stage includes a rotor 124 and stator 126. The air flow 114 flows downstream, where the guide vane 104 creates a flow distribution or flow field through the plurality of compressor stages and into the combustor, indicated by flow arrow 128.
In an embodiment, the guide vane 104 (also “inlet guide vane” or “IGV”) comprises a shape memory material (or “shape memory alloy”) that is in operable communication with the guide vane 104 to change the geometry of the guide vane 104 when an energy is applied to the shape memory material. For example, the shape memory material is embedded in or forms a portion of the interior and/or exterior of guide vane 104. The shape memory material may include a flexible composite material with a conductor or wire embedded in the composite. The wire is operably coupled to a power source 130, where the power source selectively applies energy, in the form of current and heat, to the wire. In one aspect, the power source 130 is coupled to a controller 132 to selectively apply current to the wires to change the geometry of the guide vane 104 based on turbine conditions. Conductive wire materials, such as nickel titanium (NiTi), produce a significant change in temperature when transmitting current. In an embodiment, a straight NiTi wire with a substantially straight shape is wound into a tight spiral and embedded in the composite. When a selected level of current is applied to the wire, the wire is heated to retain its previous, substantially straight shape. Accordingly, the composite shape memory material changes from a first shape to a second shape or geometry as the current carrying wire straightens. The power source 130 provides a selected level of current to the wire from a direct current (DC) source, such as a battery, a powerline-based alternating current (AC) source or any other suitable power source. A shape memory material may be described as having a shape memory property where the material remembers a plurality of different shapes based on a condition, such as an energy being applied to the material. For example, a shape memory material is configured to have one shape at low temperatures and a second shape at high temperatures. A material that shows a shape memory property during both heating and cooling may be called two-way shape memory material. As depicted, the guide vane 104 is an air foil defined by chord 134 and length 136 dimensions, wherein an aspect ratio (length/chord) is an expression of the relationship of the dimensions. In an embodiment, the aspect ratio of the guide vane 104 is substantially constant or fixed as the shape or geometry of the guide vane is changed by the shape memory material.
With continued reference to the embodiment of
In some embodiments, the entire structure of guide vane 104 includes the shape memory material, where wires are embedded throughout a composite-based structure. Such structures allow the entire geometry of the guide vane 104 to change based on current conditions. In other embodiments, selected portions or regions of the guide vane 104 structure include the shape memory material. For example, a trailing edge of the guide vane 104 comprises the shape memory material, thereby enabling the profile or geometry of the trailing edge to selectively change based on turbine conditions. In another embodiment, the leading edge changes geometry based on current selectively applied to a shape memory material located in the leading edge of the guide vane. In aspects, the shape memory material of the guide vane 104 include an alloy, flexible carbon fiber composites, conductive wires and/or nanoparticles, where the shape memory material changes shape when energy is applied to the material or selected portions of the material. The energy applied to the material may include current, voltage, electromagnetic waves, heat or other suitable energy. Although the guide vane 104 of the present embodiment is shown with a particular type of gas turbine engine 100, the guide vane may be used with any known turbine engine type, including but not limited to steam turbines, gas turbines and aeroderivative turbines. In some embodiments, it is noted that the depicted air flow through compressor 106 comprises any suitable fluid, including air, oxygen, gas fuel, liquid fuel or any combination thereof. Further, the variable geometry guide vane 104 may be positioned between various stages of the compressor 106. As discussed herein, the guide vane 104 is also referred to as an air flow control apparatus.
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.
