ADJUSTABLE TURBINE VANE COOLING

Abstract

A turbine vane cooling system operably coupling a cooling fluid source to a turbine vane assembly is disclosed herein. A plurality of turbine vanes having an airfoil shaped surface forming a substantially hollow body is connected to the turbine vane assembly. An inlet can be operably connected to each turbine vane to form a fluid communication path between a cooling fluid source and an interior of the hollow body of each turbine vane. At least one outlet fluidly communicating with the interior of said hollow body can be formed in the vane. A regulating member can variably block a portion of an inlet of each of the turbine vanes in response to a temperature of each turbine vane.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/786,390, filed 15 Mar. 2013, the disclosure of which is now expressly incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates in general to an apparatus and method for cooling a turbine vane assembly. More particularly, the present disclosure relates to controlling the flow of cooling fluid to individual turbine vanes in a gas turbine engine or the like.

BACKGROUND

Gas turbine engine designers continuously work to improve engine efficiency. The thermal efficiency of a turbofan engine is a function of component efficiencies, cycle pressure ratio, and turbine inlet temperature. As temperatures increase in the gas turbine system, cooling fluid must be diverted from the compressor to cool certain hot section components. Typically, a cooling system for turbine vanes is designed for a worst case scenario such that the same amount of cooling flow is delivered to all of the turbine vanes so that the hottest vanes will not rise above a threshold temperature due to hot spots coming from the combustor. This type of cooling system design needlessly delivers cooling flow to relatively cool turbine vanes and therefore unnecessarily degrades thermal efficiency of the gas turbine engine. Cooling systems remain an area of interest for technology improvement. Some existing gas turbine cooling systems have various shortcomings, drawbacks, and disadvantages relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology.

SUMMARY

One embodiment of the present disclosure is a unique cooling system for a turbine vane assembly. Another embodiment includes a gas turbine engine having an adjustable cooling system for controlling cooling fluid to individual turbine vanes in a turbine vane assembly. Other embodiments include unique apparatuses, systems, devices, hardware, methods, and combinations for gas turbine engine power systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present disclosure will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a schematic cross-section of a turbine engine incorporating an exemplary embodiment of the present disclosure;

FIG. 2 is a perspective view of a portion of a turbine vane assembly in an exemplary embodiment of the present disclosure;

FIG. 3 is a perspective view of a single turbine vane in an exemplary embodiment of the present disclosure;

FIG. 4 is a cross-section view of the single turbine vane shown in FIG. 3, taken through section lines 4-4;

FIG. 5 is a partial cross-section of the single turbine vane shown in FIG. 3, taken through staggered section lines 5-5;

FIG. 6 is a schematic partial cross-section of a single turbine vane according to an alternative embodiment of the present disclosure; and

FIG. 7 is a schematic partial cross-section of a single turbine vane according to yet another embodiment of the present disclosure.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

A plurality of different embodiments of the present disclosure is shown in the Figures of the application. Similar features are shown in the various embodiments of the present disclosure. Similar features have been numbered with a common reference numeral and have been differentiated by an alphabetic suffix. Also, to enhance consistency, the structures in any particular drawing share the same alphabetic suffix even if a particular feature is shown in less than all embodiments. Similar features are structured similarly, operate similarly, and/or have the same function unless otherwise indicated by the drawings or this specification. Furthermore, particular features of one embodiment can replace corresponding features in another embodiment or can supplement other embodiments unless otherwise indicated by the drawings or this specification.

In some turbine engine applications, a cooling fluid such as air is directed through portions of a turbine vane assembly to provide cooling to vanes and other portions of the turbine assembly. Typically, passageways for cooling flow are sized for worst-case conditions caused by hot streaks (variations in temperature from the mean) in the system. Hot streaks are products of the combustion gases exiting the combustor and can be harmful when impinging on one or more turbine the vanes downstream. The cooling air is typically bled from a bleed port coupled to a compressor which causes an efficiency loss for the engine cycle because the compressed air is not used for power production in the gas turbine engine. It is desirable from an engine efficiency standpoint to minimize the cooling air bled from the compressor section. Since it is generally unknown at the time the cooling system is being designed which area of the combustor might cause hot streaks, the cooling design must be able to provide maximum cooling flow for each vane in the turbine assembly. This type of cooling system design needlessly overcools many of the vanes that are not running as hot as others in the turbine assembly.

A first exemplary embodiment of the present disclosure provides for a self-regulating fluid control device operably connected with each turbine vane in a turbine assembly. In one non-limiting example, a regulating member may be made from a material having a coefficient of thermal expansion greater than that of the material used to construct the vanes. The regulating member can be disposed along a cooling fluid supply path of each vane, typically proximate a radially inner base or radially outer base of the vane. As the vane assembly heats up from exhaust gas flow, one or more vanes may “see” hotter exhaust gas flow than other vanes due to hot streaks formed in the combustion chamber. A portion of the regulating member, such as an aperture or a valve stem, can expand and contract as a function of temperature in proportion to the coefficient of thermal expansion of the material used in forming the regulating member. The aperture or valve stem associated with a relatively hot turbine vane will expand more than an aperture or valve stem of a regulating member associated with a relatively cool turbine vane causing a higher cooling flow rate into the hotter turbine vane and thus reducing the temperature of the hot vane to an acceptable level without overcooling the relatively cool turbine vanes. Thus, the disclosed adjustable cooling system provides for a passively tuned cooling system for discrete turbine blades in one embodiment of the present disclosure.

A second exemplary embodiment includes an active control system to control cooling flow to individual turbine vanes. The active control system can include an actual temperature sensor or, alternatively, a device that sends output signals that are representative of temperature such as those proportional to expansion and contraction of the vane which can indicate a relative temperature change. Proportional signal devices can include for example, strain gauges, piezoelectric sensor, or other similar devices. A strain gauge or piezoelectric sensor can be operationally connected to the vanes to send a signal to a controller that is calibrated to a temperature of a corresponding vane. The controller can command a desired position of an electronic control valve coupled between the source of the cooling fluid and the vane to control to a desired temperature. In this manner, the turbine vanes may be cooled to a desired temperature independently from one another so as to minimize the total amount of cooling fluid required to be diverted from the core passageways.

FIG. 1 schematically shows a turbine engine 10. The various unnumbered arrows represent the flow of fluid through the turbine engine 10. The turbine engine 10 can produce power for several different kinds of applications, including vehicle propulsion and power generation, among others. The exemplary embodiments of the present disclosure, as well as other embodiments of the broader invention, can be practiced in any configuration of turbine engine and in any application other than turbine engines in which cooling of various internal components is desired or required.

The exemplary turbine engine 10 can include an inlet 12 to receive fluid such as air. The turbine engine 10 can include a fan to direct fluid into the inlet 12 in alternative embodiments of the present disclosure. The turbine engine 10 can also include a compressor section 14 to receive fluid from the inlet 12 and further compress the fluid. The compressor section 14 can be spaced from the inlet 12 along a centerline axis 16 of the turbine engine 10. The turbine engine 10 can also include a combustor section 18 to receive the compressed fluid from the compressor section 14. The compressed fluid can be mixed with fuel from a fuel system 20 and ignited in a combustion chamber 22 defined by the combustor section 18. The turbine engine 10 can also include a turbine section 24 to receive the combustion gases from the combustor section 18. The energy associated with the combustion gases can be converted into kinetic energy (motion) in the turbine section 24.

In FIG. 1, shafts 26, 28 are shown disposed for rotation about the centerline axis 16 of the turbine engine 10. Alternative embodiments of the present disclosure can include any number of shafts. The shafts 26, 28 can be journaled together for relative rotation. The shaft 26 can be a low pressure shaft supporting compressor blades 30 of a low pressure portion of the compressor section 14. The compressor blades, such as blade 30, can be part of a bladed disk assembly 48 fixed for rotation with the shaft 26. The blade disk assembly 48 is shown schematically in FIG. 1. The bladed disk assembly 48 can includes a disk or rotor 50 fixed to the shaft 26 for concurrent rotation. The disk 50 can include a plurality of grooves (not visible in FIG. 1), each groove receiving a blade such as blade 30. A plurality of vanes 31 can be positioned to direct fluid downstream of the blades 30. The shaft 26 can also support low pressure turbine blades 32 of a low pressure portion of the turbine section 24.

The shaft 28 encircles the shaft 26. As set forth above, the shafts 26, 28 can be journaled together, wherein bearings are disposed between the shafts 26, 28 to permit relative rotation. The shaft 28 can be a high pressure shaft supporting compressor blades 34 of a high pressure portion of the compressor section 14. The high pressure blades, such as blade 34, can be part of a bladed disk assembly such as described above with respect to the blade 30. A plurality of vanes 35 can be positioned to receive fluid from the blades 34. The shaft 28 can also support high pressure turbine blades 36 of a high pressure portion of the turbine section 24. A plurality of vanes 37 can be positioned to direct combustion gases over the blades 36.

The compressor section 14 can define a multi-stage compressor, as shown schematically in FIG. 1. A “stage” of the compressor section 14 can be defined as a pair of axially adjacent blades and vanes. For example, the vanes 31 and the blades 30 can define a first stage of the compressor section 14. The vanes 35 and the blades 34 can define a second stage of the compressor section 14. The present disclosure can be practiced with a compressor having any number of stages.

A casing 38 defines a first wall and can be positioned to surround at least some of the components of the turbine engine 10. The exemplary casing 38 can encircle the compressor section 14, the combustor section 18, and the turbine section 24. In alternative embodiments of the present disclosure, the casing 38 may encircle less than all of the compressor section 14, the combustor section 18, and the turbine section 24.

FIG. 1 shows the turbine engine 10 having a fan 40 positioned forward of the compressor section 14 along the centerline axis 16. The fan 40 can include a plurality of blades 42 extending radially outward from a hub 44. The fan 40 can be encircled by a fan case 46. The fan case 46 can be fixed to the casing 38. The casing 38 is shown schematically as being a single structure. In some embodiments of the present disclosure, the casing 38 can be a single structure. In other embodiments of the present disclosure, the casing 38 can be formed from a plurality of members that are fixed together. The forward-most member can be designated as a “front frame.” The fan case 46 can be mounted to a front frame portion of the casing 38.

The vane 37 can be supported at a radially outer end with the casing 38 or some other static structure. The vane 37 can also be supported at a radially inner end with a static structure such as a casing 48. The casing 48 can encircle and be radially spaced from the shafts 26, 28. The casing 48 can be positioned so as to not prevent or inhibit rotation of the shafts 26, 28.

FIG. 2 is a detailed perspective view of a portion of a row of turbine vanes in the exemplary embodiment of the present disclosure. FIG. 2 shows the exemplary outer casing 38 supporting a first row 50 of vanes 37 and also supporting a second row 52 of vanes 37. The inner casing 48, shown schematically in FIG. 1, has been omitted in FIG. 2 for clarity. FIG. 3 is a perspective view of a single turbine vane in the exemplary embodiment of the present disclosure. It is noted that the shapes of the structures in the drawing figures are exemplary. Embodiments of the present disclosure can incorporate differently shaped and constructed vanes and casings, including the structures by which the vane and the casing engage one another.

The embodiment of the present disclosure provides a vane assembly. The vane assembly is designated by reference number 37. Previous uses of the reference number 37 were intended to refer to a vane assembly as described below.

Referring now to FIG. 3, the vane assembly 37 includes an airfoil shaped hollow body 54 having a leading edge 56 and trailing edge 58. FIG. 4 is a cross-section of the vane assembly 37, shown in FIG. 3, taken through section lines 4-4. FIG. 4 shows the hollow body 54 having an interior 60 capable of receiving cooling fluid. The exemplary interior 60 is shown as a generally open cavity, but it is noted that the interior 60 can define any desired cross-section, combination of passageways, and/or number of sub-cavities in embodiments of the present disclosure. For example, U.S. Pat. Nos. 6,837,683 and 7,179,047 disclose various internal structures for generally hollow airfoils. These patents are incorporated by reference herein as examples of interior structures that can be applied in alternative embodiments of the present disclosure. Also, while the exemplary embodiment of the present disclosure illustrated as being practiced with a turbine vane (a static airfoil), it should be noted that embodiments of the present disclosure can be practiced with other portions hot sections requiring a cooling fluid.

The hollow body 54 also includes a first arcuate face 62 being generally concave and a second arcuate face 64 opposite the first arcuate face 62. The second arcuate face 64 is generally convex. Fluid such as combustion gases flowing from the combustor section 18 can be directed along the first arcuate face 62 toward the first row of turbine vanes (referenced at 36 in FIG. 1).

FIG. 5 is a partial cross-section of the single turbine vane shown in FIG. 3, taken through staggered section lines 5-5. FIG. 5 shows that the vane assembly 37 also includes an inlet 66 fluidly communicating with the interior 60 of the hollow body 54. The vane assembly 37 also includes at least one outlet fluidly communicating with the interior of the hollow body 54 and spaced from the inlet 66. The form and nature of the outlet can be practiced in numerous ways in alternative embodiments of the present disclosure. For example, FIG. 5 shows a series of apertures 68 arranged adjacent to the trailing edge 58; each of these apertures 68 can be an outlet from the interior 60. In another example, a similar series of apertures can be arranged adjacent to the leading edge 56 in other embodiments of the present disclosure. Further, apertures can be positioned anywhere along an outer surface of the turbine vane as desired in other embodiments of the present disclosure. In another example, the cooling air in the interior 60 can exit through outlet positioned radially opposite the exemplary inlet 66. In the exemplary embodiment, the inlet 66 can be formed in a radially outer mounting base 70 fixed to the hollow body 54. An outlet could be formed in a radially inner mounting base 72 fixed to a radially-opposite side of the hollow body 54. In such an embodiment, the cooling fluid would travel radially inward through the entire radial height of the hollow body 54. It is also noted that in alternative embodiments of the present disclosure the inlet 66 can be formed in the radially inner mounting base 72.

Referring again to FIG. 1, the exemplary embodiment of the present disclosure also includes a cooling fluid delivery system 74. The cooling fluid delivery system 74 includes a fluid bleed 76 operable to draw fluid out of the compressor section 14. The cooling fluid delivery system 74 also includes an intake fluid passageway 78 (shown schematically) that receives fluid from the fluid bleed 76. The intake fluid passageway 78 is operable to receive cooling fluid from any source of cooling fluid other than the compressor section 14 in alternative embodiments of the present disclosure. The cooling fluid delivery system 74 also includes a fluid plenum 80 operable to receive cooling fluid from the intake fluid passageway 78. FIG. 2 shows that the casing 38 and the radially outer mounting bases 70 of the vane assemblies 37 can cooperate to form the fluid plenum 80 in the exemplary embodiment of the present disclosure. The fluid plenum 80 defines a cavity 82 for receiving fluid from the intake fluid passageway 78. It is noted that in alternative embodiments of the present disclosure, the cooling fluid delivery system 74 can be configured differently, such as having a valve disposed along the intake fluid passageway 78 between the fluid bleed 76 and the fluid plenum 80.

As best seen in FIG. 5, the vane assembly 37 also includes a regulating member 84 positioned at the inlet 66. The regulating member 84 defines an aperture 86 in fluid communication with the inlet 66. Cooling fluid can pass from the cavity 82 (shown in FIG. 2), through the aperture 86, through the inlet 66, and into the interior 60. The regulating member 84 can have higher coefficient of thermal expansion than the hollow body 54. For example, the hollow body 54 can be formed from CMSX-4 and the regulating member could be formed from 347 Stainless Steel. CMSX-4 is a high strength, single crystal alloy, developed by the Cannon Muskegon Corporation. CMSX-4 is a second generation rhenium-containing, nickel-base single crystal alloy capable of higher peak temperature/stress operation of 2125° F. (1163° C.). It should be understood that other materials can be used for the regulating member 84 and the hollow body 54.

As the operating temperature increases, the aperture 86 of the regulating member 84 can expand more quickly than the hollow body 54, increasing the amount of fluid passing into the interior 60. As the operating temperature decreases, the aperture 86 of the regulating member 84 can shrink more quickly than the hollow body 54, decreasing the amount of fluid passing into the interior 60. The increasing back pressure generated when an aperture 86 of a first regulating member 54 shrinks deters the flow of cooling fluid, allowing the cooling fluid to follow a path of lesser resistance, such as through an aperture 86 of a second regulating member 54 that is hotter than the first regulating member 54. In this manner, more cooling fluid is delivered to relatively hotter turbine vanes than to relatively cooler turbine vanes.

In the exemplary embodiment of the present disclosure, the regulating member 84 can be washer-like/ring-like in shape and the aperture 86 can be circular. However, in alternative embodiments of the present disclosure, the regulating member 84 and the aperture 86 can be shaped differently. The regulating member 84 can be engaged or mounted directly with the hollow body 54. This allows the regulating member 84 to be more responsive to temperature changes in the hollow body 54.

A retaining portion 88 can be fixed to the hollow body 54 adjacent to the inlet 66. The retaining portion 88 can be integrally-formed with the hollow body 54 or can be formed separately and subsequently attached to the hollow body 54. The exemplary retaining portion 88 can include a vertical flange portion 90 extending outward from the base 70 and a horizontal flange portion 92 extending away from a distal end of the vertical flange portion 90. The horizontal flange portion 92 can define an aperture 94 such that the aperture 86 can fluidly communicate with the cavity 82 (shown in FIG. 2).

The regulating member 84 can be positioned in the retaining portion 88. A biasing member 96 can be disposed in the retaining portion 88 adjacent to the regulating member 84. The biasing member 96 can accommodate relative size changes between the regulating member 84 and the hollow body 54 and also center the regulating member 84 in the retaining portion 88. As the regulating member 84 grows and thereby moves relative to the retaining portion 88 of the hollow body 54, the biasing member 96 can be increasingly compressed. In one non-limiting example, the exemplary biasing member 96 can be an annular spring, such as a garter spring, fully encircling the regulating member 84 and allowing the regulating member 84 to expand outward in all radial directions relative to the direction of fluid flow. Other types of biasing members are also contemplated by the present disclosure.

In the exemplary embodiment, the apertures 86 of all of the regulating members 84 fluidly communicate with and are downstream of the fluid plenum 80. In addition, the apertures 86 of the regulating members 84 are immediately upstream of the respective inlets 66 and the inlets 66 are immediately upstream of the respective interiors of the hollow bodies 54. Also, the apertures 86 of all of the regulating members 84 are immediately downstream of the fluid plenum 80. This arrangement allows for more direct control of the cooling fluid into each individual vane assembly 37. The exemplary regulating member 84 is positioned as close to the hollow body 54 as possible. It is noted that a hot streak could occur in less than all of the vane assemblies 37 in a particular row of vane assemblies. In the exemplary embodiment, the flow rates of cooling fluid could be different for two vane assemblies 37 in the same row.

The aperture 86 of the regulating member 84 can be smaller than the inlet 66. For example, the exemplary aperture 86 of the regulating member 84 can have a smaller cross-sectional area than the inlet 66 based on the direction of cooling fluid flow. This allows the aperture 86 to define the controlling orifice in the passageway for the flow of cooling fluid. The regulating member 84 can thus operate as a passive control valve to control a rate of fluid mass flow. In some embodiments of the present disclosure, the regulating member 84 could expand relative to the inlet 66 such that the aperture reaches the same size as the inlet 66, at which point the regulating member would no longer control the fluid mass flow rate.

FIG. 6 shows an alternative embodiment of the present disclosure. In FIG. 6, a vane 37 can include a hollow body 54a. The hollow body 54a can extend between a leading edge 56a and a trailing edge 58a. The hollow body 54a can define a first arcuate surface 62a. The hollow body 54a can extend radially between a radially outer mounting base 70a and a radially inner mounting base 72a. An inlet 66a can fluidly communicate with an interior 60a of the hollow body 54a and can be defined proximate the base 72a.

A regulating member 84a can include a conical portion 98a received in said inlet 66a and a rod portion 100a extending from the conical portion 98a outside of the inlet 66a. The conical portion 98a extends between a base 102a and a narrower, tip portion 104a. The rod portion 100a changes length in response to temperature changes and thereby changes a position of the conical portion 98a relative to the inlet 66a. In FIG. 6, the conical portion 98a is shown in solid line for a first position and in phantom or dashed line for a second position. The conical portion 98a can be shifted from the first position to the second position if the rod portion 100a decreases in length due to decreasing temperature. Conversely, the conical portion 98a can be shifted from the second position to the first position if the rod portion 100a increases in length due to increasing temperature.

When the conical portion 98a is in the first position, the flow of cooling fluid is generally less restricted from entering the interior 60a as the conical portion 98a fills relatively less of the cross-sectional area of the inlet 66a. Conversely, when the conical portion 98a is in the second position, the flow of cooling fluid is generally more restricted from entering the interior 60a as the conical portion 98a fills relatively more of the cross-sectional area of the inlet 66a.

It is noted that in an alternative embodiment of the present disclosure the conical portion could be arranged opposite to the orientation shown in FIG. 6. For example, the rod portion could be engaged with the base of the conical portion rather than the tip portion. In such an embodiment, the tip portion can be positioned in the interior 60a rather than the base. In such an embodiment, the regulating member could have a lower coefficient of thermal expansion than the hollow body. The inlet 66a would change size relative to the conical portion, generating more or less back pressure hindering the flow of cooling fluid into the interior 60a depending on the nature of the change in temperature. Other shapes besides cones could be applied in alternative embodiments of the present disclosure.

Referring now to FIG. 7, yet another embodiment of the present disclosure is illustrated. Control of cooling fluid flow to individual turbine vanes may also be accomplished through an active electronic control system. The configuration of the turbine vane 37a can be similar in many respects to the passively controlled cooling system depicted in FIG. 6, and as such will only be described where variations in the configuration occur. The embodiment of FIG. 7 can include a valve rod or stem 110 that can be coupled to an electronic actuator 112 for moving the regulating member 84a between an open and a closed position. A sensor 114 may be operationally coupled to an electronic controller 120 through a communication connection 122 to provide an indication of actual temperature or relative temperature of that turbine vane relative to other turbine vanes in the turbine vane assembly. The electronic controller 120 can be electronically coupled to the electronic actuator 112 through a communication connection 124. The sensor may be a temperature sensor, a piezoelectric sensor, a strain gauge or similar device to provide a signal indicative of the vane temperature to the electronic controller 120 so that the controller 120 can determine a valve position command for the electronic actuator 112. In this manner, cooling flow can be controlled to individual turbine vanes to provide a desired turbine vane temperature and reduce or eliminate wasted cooling flow that would otherwise be delivered to relatively cooler turbine vanes.

While the present disclosure has been described with reference to an exemplary embodiment, 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 of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the appended claims. Further, the “present disclosure” as that term is used in this document is what is claimed in the claims of this document. The right to claim elements and/or sub-combinations that are disclosed herein as other present disclosures in other patent documents is hereby unconditionally reserved.

Claims

1. A turbine vane cooling system comprising:

a cooling fluid system operably coupling a cooling fluid source and a turbine vane assembly;

a plurality of turbine vanes having an airfoil shaped surface forming a substantially hollow body connected to the turbine vane assembly;

an inlet operably connected to each turbine vane forming a fluid communication path between with the cooling fluid source and an interior of the hollow body of each turbine vane;

at least one outlet fluidly communicating with the interior of said hollow body of each turbine vane; and

a regulating member positioned proximate each inlet operable for blocking a variable portion of each inlet of each turbine vane.

2. The turbine vane cooling system of claim 1, wherein said regulating member is formed from a material having a higher coefficient of thermal expansion than a material forming said hollow body.

3. The turbine vane cooling system of claim 1, wherein said regulating member includes an aperture in fluid communication with said inlet.

4. The turbine vane cooling system of claim 3, wherein said aperture defines a substantially round orifice that expands and contracts with an increase or decrease, respectively, in temperature.

5. The turbine vane cooling system of claim 1 further comprising: a biasing member engaged with said regulating member.

6. The turbine vane cooling system of claim 1, further comprising:

an electronic actuator operable to move the regulating member between an open and a closed position corresponding to an open inlet flow area and a closed inlet flow area for each turbine vane.

7. The turbine vane cooling system of claim 6, wherein an electronic controller is operable for sending a position signal to each actuator coupled to a corresponding regulating member, wherein at least one position signal is different from one of the other position signals.

8. The turbine vane cooling system of claim 1 further comprising:

a sensor operable for transmitting at least one of an actual temperature signal or a signal indicative of a temperature of a turbine vane to an electronic controller.

9. The turbine vane cooling system of claim 8, wherein said sensor includes at least one of a temperature sensor, a strain gauge, and a piezoelectric sensor.

10. The vane assembly of claim 1 wherein said regulating member further comprises:

a conical portion positioned proximate said inlet; and

a rod portion extending from said conical portion, wherein said rod portion changes length in response to a temperature change causing movement of the conical portion relative to said inlet; wherein an inlet flow area increases and decreases with increasing and decreasing temperature, respectively.

11. A method comprising the steps of:

directing cooling fluid through a plurality of turbine vanes to cool the turbine vanes; and

independently controlling the flow of cooling fluid into each turbine vane with a regulating member operably connected to each turbine vane.

12. The method of claim 11, wherein the independent controlling step includes:

passively controlling a regulating member in response to a turbine vane temperature.

13. The method of claim 12, wherein passively controlling the regulating member includes expanding and contracting a portion thereof to increase or decrease in inlet flow area of a turbine vane.

14. The method of claim 11, wherein the independent controlling step includes:

actively controlling a regulating member in response to at least one of a sensed temperature and a signal indicative of a temperature.

15. The method of claim 14 further comprising:

sending a position signal from an electronic controller to an actuator in response to said sensed temperature and/or said signal indicative of said temperature.

16. A gas turbine engine comprising:

a compressor section operable to compress fluid;

a combustor section positioned downstream of said compressor section operable to receive said compressed fluid from said compressor section; and

a turbine section positioned downstream of said combustor section operable to receive combustion gases from said combustion chamber;

at least one vane assembly positioned in the turbine section operable to direct fluid further downstream, wherein the at least one vane assembly includes:

a plurality of vanes having partially hollow bodies for receiving a cooling fluid therein;

an inlet fluidly connecting a cooling source and each hollow body of the plurality of vanes;

at least one outlet fluidly communicating with the interior of said hollow body and spaced from said inlet of each of the turbine vanes; and

a regulating member operably connected with each inlet for increasing or decreasing a flow rate of cooling fluid into the inlet of each hollow body in response to a temperature of a corresponding turbine vane.

17. The gas turbine engine of claim 16, wherein said regulating member defines an aperture in fluid communication with said inlet to passively control the flow rate of the cooling fluid entering the inlet.

18. The gas turbine engine of claim 16, wherein said regulating member includes a material with a higher coefficient of thermal expansion than that of a material used to form the turbine vanes.

19. The gas turbine engine of claim 16, further comprising:

an active electronic control system operably connected to the regulating member to control an effective flow area of the inlet.

20. The gas turbine engine of claim 19, wherein said active electronic control system further includes:

a sensor coupled to each turbine vane and configured to determine a relative temperature of each turbine vane;

an electronic actuator configured to control a position of a corresponding regulating member to define an effective flow area of a corresponding inlet; and

an electronic controller operable for receiving signals indicative of temperature from each of the sensors and for transmitting a position command to each of the actuators, wherein the position command varies as a function of the temperature of each vane.