Patent Application
20090060712
This invention is directed generally to turbine airfoils, and more particularly to cooling systems of platforms of hollow turbine airfoils usable in turbine engines.
Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,500 degrees Fahrenheit. Typical turbine combustor configurations expose turbine blade assemblies to these high temperatures. As a result, turbine blades must be made of materials capable of withstanding such high temperatures. In addition, turbine blades often contain cooling systems for prolonging the life of the blades and reducing the likelihood of failure as a result of excessive temperatures.
Typically, turbine blades are formed from a root portion having a platform at one end and an elongated portion forming a blade that extends outwardly from the platform coupled to the root portion. Portions of the platform immediately adjacent to the airfoil are typically cooled with internal cooling systems in the blade. The remaining portions of the platform are typically cooled with convection cooling by cooling fluids that are contained in a region that is radially inward of the platforms. The cooling fluids are contained in this region for use in the internal cooling systems of the turbine airfoils. While the cooling fluids reduce the temperature of the platforms, the platforms remain susceptible to localized hot spots caused by exposure to the hot gases in the hot gas path because of a lack of directed cooling. Thus, a need exists for more efficiently cooling the platforms of turbine airfoils.
This invention relates to a turbine airfoil cooling system for turbine engines and, in particular, for cooling internal aspects of platforms of turbine airfoils. The turbine airfoil cooling system may include a hollow, disc post body configured to be positioned between adjacent roots of turbine airfoils. The hollow, disc post body may include a plurality of impingement orifices in an outer wall for directing cooling fluids into direct contact with inner surfaces of the turbine airfoil platforms and other components of the turbine airfoils. The impingement orifices may be sized and spaced according to localized heat loads to prevent the formation of hot spots.
The hollow, disc post body may be configured to be positioned between adjacent roots of turbine airfoils. The body may include a central cooling fluid cavity extending from a first end of the disc body to a second end of the disc body along a longitudinal axis of the disc body. The body may include an opening in an inner surface of an outer wall of the body creating a cooling fluid pathway for cooling fluids to enter the central cooling fluid cavity. The body may also include a plurality of impingement orifices in the outer wall extending between the central cooling fluid cavity and an outer surface for providing impingement cooling to inner surfaces of platforms of the turbine airfoils.
In one embodiment, the hollow disc body may include an outer surface, an inner surface opposite to the outer surface, two side surfaces opposite to each other and both generally orthogonal to the inner and outer side surfaces, and first and second ends opposite to each other and generally orthogonal to the inner and outer surfaces and to the two side surfaces, thereby forming a generally rectangular body. The two side surfaces may include lengthwise indentations that are generally parallel with the longitudinal axis of the disc body, thereby creating a generally anvil shaped cross-section of the disc body. In one embodiment, the inner surface may have a width that is less than a width of the outer surface. An intersection between a first side surface and the outer surface may be rounded and may include impingement orifices, and an intersection between a second side surface and the outer surface may be rounded and may include impingement orifices.
The turbine airfoil cooling system may also include a cooling fluid supply conduit extending through the opening in the inner surface of the outer wall of the disc post body. The cooling fluid supply conduit may have a cross-sectional area that is less than the opening in the inner surface of the outer wall of the disc post body, thereby allowing the cooling fluid supply conduit to fit into the opening. The cooling fluid supply conduit may be coupled to a conventional cooling fluid source.
An advantage of this invention is that the hollow disc post body cools the platforms of turbine airfoils without modifying the configuration of the turbine blade platforms.
Another advantage of this invention is that the impingement cooling fluids are not discharged into the gas path and can be redirected to the airfoil for reuse, thereby improving efficiency by reducing cooling fluid waste flows and minimizing cooling flow usage.
Yet another advantage of this invention is that the turbine blades are not modified and do not require additional fabrication for use with the hollow disc post body.
Another advantage of this invention is that the hollow disc post body is sheltered from the hot gas path, thereby resulting in robust durability.
Still another advantage of this invention is that the hollow disc post body is positioned in a low stress region.
Another advantage of this invention is that stress concentrations at the top of the cooling fluid supply conduit are less than the stress concentrations at the disc feed holes at the live rim.
Yet another embodiment of this invention is that the cooling fluids could also be exhausted as film cooling air in an alternative embodiment.
These and other embodiments are described in more detail below.
The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the presently disclosed invention and, together with the description, disclose the principles of the invention.
As shown in
As shown in
The hollow, disc post body 16 may also be formed from two side surfaces 30, 32, that are opposite to each other and both generally orthogonal to the inner and outer side surfaces 26, 24. The hollow, disc post body 16 may be have any configuration necessary to hold it in place while the engine is running. However, in one embodiment, the two side surfaces 30, 32 may include lengthwise indentations 34 that are generally parallel with a longitudinal axis 36 of the disc body 16, thereby creating a generally anvil shaped cross-section of the disc body 16. An intersection 42 between a first side surface 30 and the outer surface 24 may be rounded and may include impingement orifices 20, and an intersection 44 between a second side surface 32 and the outer surface 24 may be rounded and may include impingement orifices 20. The hollow, disc post body 16 may also be formed from first and second ends 38, 40 opposite to each other and generally orthogonal to the inner and outer surfaces 26, 24 and to the two side surfaces, 30, 32. In one embodiment, as shown in
The hollow, disc post body 16 may include a central cooling fluid cavity 46 extending from the first end 38 of the disc body 16 to the second end 40 of the disc body 16 along the longitudinal axis 36 of the disc body 16. The disc body 16 may include an opening 48 in the inner surface 26 of the outer wall 23 of the body 16 creating a cooling fluid pathway for cooling fluids to enter the central cooling fluid cavity 46. The hollow, disc post body 16 may also include a plurality of impingement orifices 20 in the outer wall 23 extending between the central cooling fluid cavity 46 and the outer surface 24 for providing impingement cooling to the inner surfaces 22 of the platforms 12 of the turbine airfoils 14. The impingement orifices 20 may be aligned in rows or may be positioned in other appropriate arrangements.
The turbine airfoil cooling system 10 may also include a cooling fluid supply conduit 50 extending through the opening 48 in the inner surface 26 of the outer wall 23 of the disc post body 16. The cooling fluid supply conduit 50 may have a cross-sectional area that is less than the opening 48 in the inner surface 26 of the outer wall 23 of the disc post body 16, thereby enabling the cooling fluid supply conduit 50 to extend through the opening 48 and terminate in the central cooling fluid cavity 46. The cooling fluid supply conduit 50 may be coupled to a conventional cooling fluid source in the turbine engine. As shown in
The hollow disc post body 16 may be generally aligned with the roots 18 of adjacent turbine airfoils 14, as shown in
The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of this invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of this invention.
