Embodiments of the invention relate to airfoil profiles in gas turbines. More specifically, embodiments of the invention relate to airfoil profiles for inlet guide vanes (IGVs) of gas turbines.
In gas turbines, IGVs condition flow coming into the turbine to enhance efficiency and performance. The IGVs project from the center structure of the inlet, are arranged around the circumference of the turbine inlet, span at least part of the flow path between the inlet inner barrel or center structure and inlet casing, and work in concert with the profile of the inlet itself to deliver flow having desired characteristics to the first rotor of the turbine. For example, incoming flow direction, speed, and pressure can be directed to desired values.
In some gas turbines, the IGVs' angle of attack can be varied to control turbine flow rate. For example, the IGVs in some turbines are mounted on radial shafts that are rotated by actuators in the turbine housing to vary the IGV rotational position and angle of attack. As angle of attack increases, incoming flow rate decreases, and as angle of attack decreases, incoming flow rate increases. It has been observed that in such variable IGV arrangements, vibration of blades downstream of the IGV can vary significantly with changes in flow setting, which could reduce turbine and turbine component life. Investigation revealed that a component of the vibration is induced by non-uniform flow separation of the IGVs, and that at a reduced flow setting, IGV flow separation becomes very sensitive to inlet flow distortions. As a result, IGVs at some locations experience more flow separation than others, and the wakes of IGVs experiencing enhanced flow separation excite certain of the observed frequencies of vibration.
Embodiments disclosed herein include an article of manufacture with an airfoil having a nominal profile substantially in accordance with Cartesian coordinate values of x, y, and z set forth in TABLE 1. The airfoil can be produced using the TABLE 1 values and a scaling factor. The TABLE 1 x and y values are distances in inches, within a tolerance, which, when connected by smooth curves, define airfoil profile sections at each distance z in inches, the profile sections at the z distances being joined smoothly with one another to form a complete airfoil shape. As disclosed herein, the airfoil of an embodiment is an inlet guide vane, such as for a gas turbine engine. The tolerance in an embodiment can be 0.16 inches normal to any surface of the airfoil.
An embodiment includes a gas turbine with a plurality of articles of manufacture each including an airfoil produced using coordinate values of x, y, and z set forth in TABLE 1. The TABLE 1 x and y values are distances in inches, within a tolerance, which, when connected by smooth curves, define airfoil profile sections at each distance z in inches, the profile sections at the z distances being joined smoothly with one another to form a complete airfoil shape. As disclosed herein, the airfoil of an embodiment is an inlet guide vane, such as for a gas turbine engine. The tolerance in an embodiment can be 0.16 inches normal to any surface of the airfoil.
An embodiment includes a gas turbine with a plurality of articles of manufacture each including an airfoil having an uncoated nominal airfoil profile substantially in accordance with coordinate values of x, y, and z set forth in TABLE 1. The TABLE 1 x and y values are distances in inches, within a tolerance, which, when connected by smooth curves, define airfoil profile sections at each distance z in inches, the profile sections at the z distances being joined smoothly with one another to form a complete airfoil shape. As disclosed herein, the airfoil of an embodiment is an inlet guide vane, such as for a gas turbine engine. The tolerance in an embodiment can be 0.16 inches normal to any surface of the airfoil.
With reference to the accompanying Figures, examples of an inlet guide vane according to embodiments of the invention are disclosed. For purposes of explanation, numerous specific details are shown in the drawings and set forth in the detailed description that follows in order to provide a thorough understanding of embodiments of the invention. It will be apparent, however, that embodiments of the invention may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.
Referring now to the drawings,
The configuration of the airfoil and any interaction with surrounding airfoils, as embodied by the invention, that provide the desirable aspects fluid flow dynamics and laminar flow of the invention can be determined by various means. For a given airfoil downstream of the inlet guide vanes, fluid flow from a preceding/upstream airfoil intersects with the airfoil, and via the configuration of the instant airfoil, flow over and around the airfoil, as embodied by the invention, is enhanced. In particular, the fluid dynamics and laminar flow from the airfoil, as embodied by the invention, is enhanced. There is a smooth transition fluid flow from the preceding/upstream airfoil(s) and a smooth transition fluid flow to the adjacent/downstream airfoil(s). Moreover, the flow from the airfoil, as embodied by the invention, proceeds to the adjacent/downstream airfoil(s) and is enhanced due to the enhanced laminar fluid flow off of the airfoil, as embodied by the invention. Therefore, the configuration of the airfoil, as embodied by the invention, assists in the prevention of turbulent fluid flow in the unit comprising the airfoil, as embodied by the invention.
For example, but in no way limiting of the invention, the airfoil configuration (with or without fluid flow interaction) can be determined by computational Fluid Dynamics (CFD); traditional fluid dynamics analysis; Euler and Navier-Stokes equations; for transfer functions, algorithms, manufacturing: manual positioning, flow testing (for example in wind tunnels), and modification of the airfoil; in-situ testing; modeling: application of scientific principles to design or develop the airfoils, machines, apparatus, or manufacturing processes; airfoil flow testing and modification; combinations thereof, and other design processes and practices. These methods of determination are merely exemplary, and are not intended to limit the invention in any manner.
As noted above, the airfoil configuration (along with its interaction with surrounding airfoils), as embodied by the invention, including its peripheral surface, provides for stage airflow efficiency, enhanced aeromechanics, smooth laminar flow from stage to stage, reduced thermal stresses, enhanced interrelation of the stages to effectively pass the airflow from stage to stage, and reduced mechanical stresses, among other desirable aspects of the invention, compared to other similar airfoils, which have like applications. Moreover, and in no way limiting of the invention, in conjunction with other airfoils, which are conventional or enhanced (similar to the enhancements herein), the airfoil, as embodied by the invention, provides an increased efficiency compared to previous individual sets of airfoils. This increased efficiency provides, in addition to the above-noted advantages, a power output with a decrease the required fuel, therefore inherently decreasing emissions to produce energy. Of course, other such advantages are within the scope of the invention.
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To define the airfoil shape or profile 12 of the IGV 10, a unique set of points in space were derived by analytical means, such as by iteration of mechanical and aerodynamic loadings and flow conditions in a modeling computer software application. More specifically, to define the airfoil profiles 12 of the IGV 10, a unique set of points in space were derived using modeling computer software at respective spanwise positions on the blade. Local inflow distortions at each spanwise position were considered and each profile was derived with the goals of minimizing total pressure drop, broadening the separation-free range of operation vs. angle of attack to match the predicted inflow distortion, and satisfying mechanical requirements for strength, vibrational stress, and ease of manufacture. The profiles are interpolated to define the entire blade surface. This process is carried out in a computer software environment, such as a proprietary computer software environment. Fully three-dimensional computer analyses and scale model testing of the combined IGV and engine inlet were conducted to validate the design. The unique set of points is described using the Cartesian coordinate system of three mutually perpendicular axes x, y, and z. An example unique set of points is set forth in TABLE 1 below and is sufficient to enable manufacture of the IGV 10, such as with a “CNC” machine or other suitable apparatus, or by another method, such as casting, for example. Producing an IGV following the unique set of points yields an IGV that drives the initiation of flow separation from the IGVs to lower flow conditions than previous IGVs. As a result, vibration resulting from flow separation is significantly reduced, increasing reliability and reducing vibration-induced stresses on the IGVs and other components of the gas turbine.
The Cartesian coordinate system used to describe the unique set of points is oriented so that each subset of the unique set of points defines a planar section starting from the blade outer diameter (section A-A just inside blade “palm”) to the blade inner diameter (section BB-BB).
By defining x and y coordinate values at selected locations in a z direction normal to the x-y plane and connecting the x-y points with smooth curves, the profile section of the blade at each z distance along the length of the blade can be defined. By connecting each section with smooth surfaces, the entire blade is described and can be formed. It should be noted that the values in TABLE 1 are for non-operational, ambient conditions of the bare material of the blade.
The table values are generated and shown to three decimal places in the x-y plane of each section and three decimal places along the z-axis. Manufacturing tolerances and coatings that might be applied should be taken into account for the actual profile of the airfoil. For example, each coordinate value should be read as including typical manufacturing tolerances, such as ±0.16 inches for example, though other tolerances can be employed as appropriate for particular applications, all in accordance with an embodiment of the invention. Thus, any value in the table defines a range of variation between the ideal points represented in the table and measured points on the actual finished airfoil surface at ambient conditions. The IGV airfoil design of embodiments is not impaired in its performance as a result of these variations. While embodiments of the invention are described having numerical values with a three decimal place accuracy and having particular manufacturing tolerances, it will be appreciated that this is for discussion purposes only and that the scope of the invention is not so limited. As such, it will be appreciated that the scope of the invention also includes other numerical values having less than or greater than a three decimal place accuracy, and other types and values of manufacturing tolerances.
The particular values given in TABLE 1 can be scaled up or down to yield a different sized IGV. In such instances, a scaling factor can be applied to all values such that the IGV remains substantially identical in its proportions, but is larger or smaller in accordance with the scaling factor. The values in TABLE 1, for example, have a scaling factor of 1.
The coordinate values given in TABLE 1 below provide the nominal profile envelope for an exemplary inlet guide vane according to an embodiment.
While the instant disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope thereof. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
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Number | Date | Country | |
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20100068045 A1 | Mar 2010 | US |