Patent Grant
8585360
The present invention relates generally to turbines and more specifically to turbine vanes. In particular, embodiments of the invention pertain to improved vane airfoil profiles.
In a gas turbine engine, air is pressurized in a compressor then mixed with fuel and burned in a combustor to generate hot combustion gases. These pressurized hot combustion gases are expanded within a turbine section that may include multiple stages of rotary blades. The expanding gases cause the blades to rotate to power an upstream machine such as a generator to produce electricity, or otherwise generate a work load. A turbine stage may include a row of stationary vanes followed by a row of rotating turbine blades, where the turbine blades extract energy from the hot combustion gas for powering the compressor and providing output power as described. The stationary turbine vanes control the gas flow between successive turbine blades. In particular, the turbine vanes having intricately designed airfoil profiles to redirect gas flow exiting turbine blades, while minimizing temperature and pressure loss of the expanding gas.
One of the primary demands of turbine machine is maximizing the efficiency of the turbine operation. That is, generating more power or energy using less fuel. Various components of a turbine, for example vanes and blades, are constantly upgraded or modified to meet these demands. These turbine vanes and turbine blades are being constantly redesigned to meet the demands associated with the technological advances of turbines. More specifically, the airfoil profile of vanes and blades may be reconfigured to enhance the efficiency of turbine operations. By way of example, existing turbine machines that have been in operation over a number of years, and in some instance for decades, are often upgraded, which may result in the turbine vanes or blades airfoil profiles shifting away from an optimum aerodynamic design point. Accordingly, a need exists for an improved airfoil profile of a turbine vane, and especially a second stage turbine vane airfoil profile, to improve the aerodynamic efficiency of a turbine section of a turbine machine.
The invention is explained in the following description in view of the drawings that show:
Referring now to
With respect to
Also shown in
In an embodiment, the airfoil configuration represented in the
The airfoil profile or contour of the intermediate section 13A of vane 13 introduces a bowed stacking of eleven sections taken along the Z axis. As shown in Table I, there are eleven different Z coordinate values provided at nineteen (19) millimeter (mm) height increments. Each of the X, Y and Z coordinate values are provided to four decimal places. The span of the airfoil profile or the airfoil section 13A has an overall smooth contour. The X and Y values define a set of points for each Z value which when connected by smooth continuing arcs define an airfoil profile of the intermediate section of the vane, and the profile sections at the Z heights are joined smoothly with one another to form an airfoil shape of the intermediate portion.
An uncoated vane will have a nominal airfoil profile tolerance of ±2.5 mm normal to any airfoil surface location thereby defining an airfoil profile range at any such surface location. Any manufacturing tolerances, thickness of coatings etc., are in addition to the described profile tolerance. In addition, the profile tolerance may include a ±1° of rotation around an airfoil stacking axis or the Z axis of the Cartesian coordinate system.
The Cartesian coordinate values set forth in Table I are provided in millimeters and define an embodiment of the nominal airfoil profile for the intermediate section 13A of stationary vane 13.
An optimized parabolic curvature was followed to model the bowed shape of the vane 13 along the radial height enclosed between shroud 11 and 12. The vane turning angle has been adapted to improve flow incidence, eliminate separation and re-align the gas flow into the downstream rotary blade. The trailing edge 15 thickness was reduced to lower trailing edge loss. The leading edge 14 region was modified to make the vane 13 tolerant to wide swings in incidence. This enhances the vane's 13 long term durability by enabling the use of the vane 13 in various operating conditions without separation occurring and thereby reducing loss and heat transfer issues. The bowed shape of the airfoil profile enhances radial loading balance, reduces endwall (suction side 16 and pressure side 17) losses and delivers uniform flow to the downstream components.
While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.
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| Number | Date | Country | |
|---|---|---|---|
| 20120063908 A1 | Mar 2012 | US |
