Turbine blade with sectioned pins

A turbine blade is provided and includes pressure and suction surfaces connected to define an interior through which coolant is passable and first and second pedestal arrays, each of the first and second pedestal arrays including pedestals respectively coupled to radially outboard portions of respective interior faces of one of the pressure and suction surfaces. The pedestals of the first pedestal array are separated from pedestals of the second pedestal array by gaps respectively defined therebetween.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to turbine blades and, more particularly, to turbine blades with sectioned pins.

A turbine blade may be disposed in a turbine section of a gas turbine engine. The turbine blade may be installed as part of an array of turbine blades in one of multiple axially arranged stages of the turbine section. As each array aerodynamically interacts with combustion gases, the array rotates about a rotor extending through the turbine section and causes corresponding rotation of the rotor that can be used to drive a compressor and a load.

When tuning natural frequencies of a turbine blade, one can increase the frequency by increasing the stiffness of the blade and/or reducing the mass of the blade (vice versa for reducing the frequency). However, since increasing stiffness usually involves adding mass, tuning can become challenging due to the competing nature of these tuning knobs.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, turbine blade is provided and includes pressure and suction surfaces connected to define an interior through which coolant is passable and first and second pedestal arrays, each of the first and second pedestal arrays including pedestals respectively coupled to radially outboard portions of respective interior faces of one of the pressure and suction surfaces. The pedestals of the first pedestal array are separated from pedestals of the second pedestal array by gaps respectively defined therebetween.

According to another aspect of the invention, a turbine blade is provided and includes pressure and suction surfaces connected to define an interior through which a coolant is passable and first and second pedestal arrays, each of the first and second pedestal arrays including extended pedestals respectively coupled to respective interior faces of one of the pressure and suction surfaces and pedestals respectively coupled to radially outboard portions of respective interior faces of one of the pressure and suction surfaces. The pedestals of the first pedestal array are separated from pedestals of the second pedestal array by gaps respectively defined therebetween.

According to yet another aspect of the invention, a method of forming a turbine blade is provided and includes creating a cavity forming ceramic core including an elongate element having pedestal forming recesses separated from pedestal forming recesses by gap forming core portions, forming pressure and suction sides of the turbine blade on either side of the elongate element such that the pressure and suction sides include pedestals formed in the pedestal forming recesses and assembling the pressure and suction sides of the turbine blade together such that the pressure side pedestals are separated from the suction side pedestals by gaps having dimensions similar to the gap forming core portions.

DETAILED DESCRIPTION OF THE INVENTION

With reference toFIGS. 1 and 2, a turbine blade10is provided for use in, e.g., a gas turbine engine in which the turbine blade10is installed in a turbine section where combustion gases are expanded to produce work. The turbine blade10may be installed as part of an array of turbine blades in one of multiple axially arranged stages of the turbine section. As each array aerodynamically interacts with the combustion gases, the array rotates about a rotor extending through the turbine section. The rotation of the array causes corresponding rotation of the rotor that can be used to drive rotation of a compressor and a load.

The turbine blade10includes a pressure surface11and a suction surface12that are arranged oppositely with respect to one another. Both the pressure surface11and the suction surface12have a similar span that extends along a radial dimension of the rotor. The pressure surface11and the suction surface12may be connected to one another at a leading edge13and a trailing edge14such that they define an interior15. The turbine blade10may further include baffles16(seeFIG. 2) extending through the interior15along portions of the spans of the pressure surface11and the suction surface12. The baffles16define pathways17or cavities18by which coolant can be directed and passed through the interior15. The cavity18proximate to the trailing edge14will be referred to herein as a “trailing edge cavity”180.

The turbine blade10further includes a first pedestal array20and a second pedestal array30. The first pedestal array20includes a pedestal21coupled to at least a radially outboard portion of an interior face111of the pressure surface11in the trailing edge cavity180. The second pedestal array30includes a pedestal31coupled to at least a radially outboard portion of an interior face121of the suction surface12in the trailing edge cavity180. As shown inFIG. 2, it is to be understood the pedestals21and31may be provided as a first plurality of pedestals21and as a second plurality of pedestals31. For purposes of clarity and brevity, the case in which the pedestals21and31are provided as the first plurality of pedestals21and as the second plurality of pedestals31will be described below. It is also to be understood that the pedestals21and31need not be located only in the trailing edge cavity180.

The radially outboard portion of the interior face111and the radially outboard portion of the interior face121are defined at a radially outboard portion ROPSof the span. Thus, in accordance with embodiments, the first plurality of pedestals21and the second plurality of pedestals31are provided at least at the radially outboard portion ROPSof the span (seeFIG. 6). In accordance with further embodiments, however, the first plurality of pedestals21and the second plurality of pedestals31may be provided along the entirety of the span.

Each individual pedestal22of the first plurality of pedestals21of the first pedestal array20may, but is not required to, correspond in location to a corresponding individual pedestal32of the second plurality of pedestals31of the second pedestal array30. That is, in accordance with alternative embodiments, the individual pedestals22may be misaligned with respect to the individual pedestals32. In addition, each individual pedestal22is separated by a gap40from one or more of the individual pedestals32. As shown inFIG. 2, since a gap40is provided for at least pairs of individual pedestals22and32, the turbine blade10is provided with multiple gaps40.

In accordance with embodiments, the gap40may be about 0.03 inches wide although this is not required and embodiments exist in which the gap40is wider or narrower and where the size of the gap40varies. More generally, the gap40is larger than any gap that would normally be found in a conventional turbine blade as a result of manufacturing tolerances resulting from the shape and size of the conventional ceramic core and the injection molding or casting of the conventional pressure and suction sides.

In accordance with further embodiments, the interior15of the turbine blade10may be but is not required to be devoid of a pin that extends along an entirety of the distance between the interior face111of the pressure surface11and the interior face121of the suction surfaces12(i.e., the turbine blade10may be configured such that it does not include “fully elongated” pins). However, where the turbine blade10does include fully elongated pins, the baffles16may be distinguished from such fully elongate pins in that the baffles16extend along a substantial length of the spans of the pressure and suction surfaces11and12and thereby define the overall shapes and sizes of the pathways17, the cavities18generally and the trailing edge cavity180particularly.

With reference toFIGS. 3-5, various embodiments will now be described. As shown inFIG. 3, all or a portion of the gaps40may be defined along a mean camber line50of the turbine blade10where the mean camber line50is cooperatively defined by the respective shapes of the pressure and suction surfaces11and12. Alternatively, although not shown inFIG. 3, it is to be understood that all or a portion of the gaps40may be defined on one side of the mean camber line50. As shown inFIG. 4, all or a portion of the gaps40may be defined on both sides of or along the mean camber line50. In these embodiments, all or a portion of adjacent gaps40may be defined on opposite sides of the mean camber line50. Alternatively, a distribution of all or a portion of the gaps40may be defined on each side of the mean camber line50at random. As shown inFIGS. 3 and 4, all or a portion of the gaps40may be defined in parallel with the mean camber line50. Alternatively, as shown inFIG. 5, all or a portion of the gaps40may be oriented transversely or non-parallel with respect to the mean camber line50.

In addition, as shown inFIGS. 3 and 4, individual extended pedestals220,320may be respectively coupled to the respective interior faces111,121of the pressure and suction surfaces11and12. The individual extended pedestals220,320are distinguished from the individual pedestals22and32in that the individual extended pedestals220extend from the interior face111and are separated from the interior face121by corresponding gaps40while the individual extended pedestals320extend from the interior face121and are separated from the interior face111by corresponding gaps40.

In each case, the embodiments ofFIGS. 3-5may be provided alone or in various combinations with one another. Generally, the size, shape and orientation of the individual pedestals22and32and the gaps40may be provided in accordance with various design considerations of the turbine blade10. For example, when tuning natural frequencies of a turbine blade, one can increase the frequency by increasing the stiffness of the blade and/or reducing the mass of the blade (vice versa for reducing the frequency). However, since increased stiffness may involve adding mass, tuning can become challenging due to the competing nature of these tuning effects. That is, the frequency of a blade with trailing edge motion can be altered if the stiffness could be affected without appreciably impacting the mass. This can be accomplished in accordance with the embodiments described herein. By providing the gaps40between the individual pedestals22and32(i.e., by separating the individual pedestals22and32), the pressure side of the turbine blade10can be decoupled from the suction side and stiffness can be reduced. However, by maintaining the individual pedestals22and32and making the gaps40relatively small, the mass of the turbine blade10is negligibly affected.

In accordance with further aspects of the invention, the size, shape and orientation of the individual pedestals22and32and the gaps40may be provided in accordance with various particular design considerations of the turbine blade10. For example, more effectively cooling relatively hotter regions on the pressure surface11or the suction surface12may be accomplished by the provision of longer individual pedestals22proximate to the hotter region, thus enhancing the fin effectiveness in that region.

With reference toFIG. 6, a method of forming the turbine blade10will now be described. The method includes creating a ceramic core60that can be used to form the trailing edge cavity180. As shown inFIG. 6, the ceramic core60includes an elongate element61having pin forming recesses62and gap forming core portions63at least at the radially outboard portion ROPSof the span. The gap forming core portions63are disposed between the pedestal forming recesses62such that the individual pedestals21and31will be separate from one another. The elongate element61further includes trailing edge hole forming portions64, which are arrayed along a side of the elongate element61to be used to form trailing edge holes640in the turbine blade (seeFIG. 2).

Once the ceramic core60is created, the method further includes casting (or another similar manufacturing method or process) of pressure and suction sides of the turbine blade10on either side of the elongate element61such that the pressure and suction sides include the above-described individual pedestals22and32formed in the pedestal forming recesses62and assembling the pressure and suction sides of the turbine blade10together such that the pressure side individual pedestals22are separated from the suction side individual pedestals32by the gaps40having dimensions similar to the gap forming core portions63.

Although the method as described above relates to cast components, it is to be understood that this is not required and that other manufacturing methods and processes may be employed for other types of components. For example, the individual pedestals22and32may be formed in part that is assembled or fabricated. Such a part may be provided as buckets, blades, nozzles or any other gas turbine components.

As described herein, a manufacturing process of the ceramic core60may be simplified as compared to conventional processes. In accordance with the embodiments described herein, the ceramic core60is created such that the gaps40are formed directly and preserved. Core yield may be thereby improved.