Turbine airfoil with near wall inflow chambers

A turbine airfoil usable in a turbine engine and having at least one cooling system. At least a portion of the cooling system may be positioned in an outer wall of the turbine airfoil for receiving cooling fluids from a cooling fluid supply source, passing those fluids through the chambers in the outer wall, and exhausting those fluids into central cooling fluids collection chambers. The outer wall may include a plurality of outer wall cooling chambers that may be configured to pass cooling fluids in a counter flow direction. The outer wall cooling chambers may include a plurality of ribs including a plurality of impingement orifices for increasing the cooling efficiency of the cooling system.

FIELD OF THE INVENTION

This invention is directed generally to turbine airfoils, and more particularly to hollow turbine airfoils having cooling channels for passing fluids, such as air, to cool the airfoils.

BACKGROUND

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 vane and blade assemblies to these high temperatures. As a result, turbine vanes and blades must be made of materials capable of withstanding such high temperatures. In addition, turbine vanes and blades often contain cooling systems for prolonging the life of the vanes and blades and reducing the likelihood of failure as a result of excessive temperatures.

Typically, turbine vanes are formed from an elongated portion forming a vane having one end configured to be coupled to a vane carrier and an opposite end configured to be movably coupled to an inner endwall. The vane is ordinarily composed of a leading edge, a trailing edge, a suction side, and a pressure side. The inner aspects of most turbine vanes typically contain an intricate maze of cooling circuits forming a cooling system. The cooling circuits in the vanes receive air from the compressor of the turbine engine and pass the air through the ends of the vane adapted to be coupled to the vane carrier. The cooling circuits often include multiple flow paths that are designed to maintain all aspects of the turbine vane at a relatively uniform temperature. At least some of the air passing through these cooling circuits is exhausted through orifices in the leading edge, trailing edge, suction side, and pressure side of the vane. While advances have been made in the cooling systems in turbine vanes, a need still exists for a turbine vane having increased cooling efficiency for dissipating heat and passing a sufficient amount of cooling air through the vane.

SUMMARY OF THE INVENTION

This invention relates to a turbine airfoil having an internal cooling system for removing heat from the turbine airfoil. The turbine airfoil may be formed from a generally elongated hollow airfoil having a leading edge, a trailing edge, a pressure side, a suction side, a first end adapted to be coupled to a hook attachment, a second end opposite the first end and adapted to be coupled to an inner endwall, and a cooling system in the outer wall. The cooling system may be formed from one or more pressure side outer wall chambers and one or more suction side outer wall chambers positioned in the outer wall of the turbine airfoil. The pressure and suction side outer wall chambers may be configured to receive cooling fluids directly from a cooling fluid supply source, such as a compressor (not shown), and pass the cooling fluids into one or more central cooling fluid collection chambers to cool internal aspects of the turbine airfoil. Passing the cooling fluids through the pressure and suction side outer wall chambers first before passing the cooling fluids through other portions of the cooling system provides enhanced cooling capabilities to the turbine airfoil and reduces stress inducing temperature gradients that exist at operating conditions between the outer wall and internal aspects, such as internal ribs, of the turbine airfoil.

The pressure and suction side outer wall chambers may each include one or more chambers. In one embodiment, the suction side outer wall chamber may include a forward, mid, and aft suction side outer wall chamber. The pressure side outer wall chamber may include a forward and aft pressure side outer wall chamber. The pressure and suction side outer wall chambers may include ribs with impingement orifices for increasing the effectiveness of the cooling system. In particular, the pressure and suction side outer wall chambers may include a repeating pattern of ribs having impingement holes that are offset generally in the spanwise direction relative to impingement orifices in a downstream rib. In such a configuration, cooling fluids passing through the impingement ribs impinge on the rib downstream of the impingement holes and reduce the temperature of that rib.

The pressure and suction side outer wall chambers may be coupled to a central cooling fluid collection chamber through a pressure side cooling fluid turn and a suction side cooling fluid turn, respectively. The pressure side cooling fluid turn may be formed from forward and aft pressure side cooling fluid turns in communication with the forward and aft pressure side outer wall chambers, respectively. The suction side cooling fluid turn may be formed from forward, mid, and aft suction side cooling fluid turns in communication with the forward, mid, and aft suction side outer wall chambers, respectively.

The cooling system may also include one or more central cooling fluid collection chambers configured to receive cooling fluids from the pressure and suction side outer wall chambers. In one embodiment, the central cooling fluid collection chamber may be formed from a forward, mid, and aft central cooling fluid collection chamber. The cooling system may also include a leading edge impingement chamber in communication with the forward central cooling fluid collection chamber through one or more impingement orifices. The leading edge impingement chamber may exhaust cooling fluids from the airfoil through one or more film cooling orifices forming a showerhead. The cooling system may also include a trailing edge impingement chamber in communication with the aft central cooling fluid collection chamber through one or more impingement orifices. The trailing edge impingement chamber may exhaust cooling fluids from the airfoil through one or more trailing edge exhaust orifices. Cooling fluids may also be exhausted from the central cooling fluid collection chambers through one or more film cooling orifices.

During operation, the cooling fluids flow from a cooling fluid supply source through an endwall at the OD of the turbine airfoil. The cooling fluids may flow into the pressure and suction side outer wall chambers. The cooling fluids increase in temperature upon receiving heat from the turbine airfoil as the cooling fluids flow through the impingement orifices of the suction and pressure side outer wall chambers. In particular, as cooling fluids flow through the impingement orifices the cooling fluids impinge on the rib and cool the rib. Similarly, as cooling fluids flow through the impingement orifices, the cooling fluids impinge on the rib and cool the rib. This cooling mechanism is repeated throughout the pressure and suction side outer wall chambers. The cooling fluids then flow through the pressure or suction side cooling fluid turns and into the central cooling fluid collection chamber. Cooling fluids flow into the forward, mid, and aft central cooling fluid collection chambers. The cooling fluids entering the forward, mid, and aft central cooling fluid collection chambers have been heated while passing through the pressure and suction side outer wall chambers. As a result, a smaller temperature gradient is established between the ribs forming the forward, mid, and aft central cooling fluid collection chambers and the outer wall than in conventional airfoils. The cooling fluids may be expelled out of the central cooling fluid collection chamber and into the leading edge impingement chamber, the trailing edge impingement chamber, and through film cooling holes in the outer wall of the airfoil. The cooling fluids maybe exhausted from the leading edge impingement chamber through a plurality of film cooling holes extending through the outer wall forming a showerhead, a pressure side film cooling hole, and a suction side film cooling hole. The cooling fluids may be exhausted from the trailing edge impingement chamber through exhaust orifices extending through the outer wall of the trailing edge.

An advantage of this invention is that each individual cooling circuit formed from the pressure and suction side outer wall chambers may be independently designed based on local heat load and aerodynamic pressure loading conditions.

Another advantage of this invention is that the multiple impingement ribs having the multiple impingement orifices in the pressure and suction side outer wall chambers enables the airfoil cooling system to easily be reconfigured for cooling demand growth in other portions of the turbine engine.

Yet another advantage of this invention is that the cooling fluid flow is metered with the impingement ribs in the pressure and suction side outer wall chambers thereby yielding an excellent cooling fluid control device.

Another advantage of this invention is that the pressure and suction side outer wall chambers are separated from each other which thus eliminates conventional non-uniform distribution of mid-chord cooling fluid flow due to pressure variations in the mid-chord.

Still another advantage of this invention is that the configuration of the pressure and suction side outer wall chambers receiving the cooling fluids first reduces the thermal gradient present between the outer wall of turbine engine and the inner aspects of the airfoil under steady state operating conditions as compared with conventional designs. This is the case because relatively cold cooling fluids are first passed through the pressure and suction side outer wall chambers where the cooling fluids are heated. The heated cooling fluids are then passed to the central cooling fluid collection chambers at a temperature greater than when the cooling fluids entered the pressure and suction side outer wall chambers.

Another advantage of this invention is that the film cooling holes positioned in the outer walls and in communication with the central cooling fluids collection chambers have longer lengths than conventional film cooling orifices coupled to near wall cooling chambers. Such a configuration enables the film cooling orifices to have a well defined geometry, which is difficult to obtain with film cooling orifices extending from near wall cooling chambers.

Yet another advantage of this invention is that the cooling fluids flowing in the suction and pressure side outer wall chambers and through the plurality of impingement orifices spread out around the impingement jet stagnation points through the impingement cavities formed by the ribs in the suction and pressure side outer wall chambers and contact and cool the walls forming these components of the airfoil. This additional cooling characteristic increases the efficiency of the cooling system.

DETAILED DESCRIPTION OF THE INVENTION

As shown inFIGS. 1-5, this invention is directed to a turbine airfoil10having a cooling system12in inner aspects of the turbine airfoil10for use in turbine engines. The cooling system12may be used in any turbine vane or turbine blade. While the description below focuses on a cooling system12in a turbine vane10, the cooling system12may also be adapted to be used in a turbine blade. The cooling system12may be configured such that adequate cooling occurs within an outer wall14of the turbine vane10by including one or more cavities16in the outer wall14and configuring each cavity16based on local external heat loads and airfoil gas side pressure distribution in both chordwise and spanwise directions. The chordwise direction is defined as extending between a leading edge40and a trailing edge42of the airfoil10. The spanwise direction is defined as extending between an inner endwall38and an endwall32at the first end33. In particular, the cooling system12may include one or more pressure side outer wall chambers18and one or more suction side outer wall chambers20positioned in the outer wall14of the turbine airfoil10. The pressure and suction side outer wall chambers18,20may be configured to receive cooling fluids directly from a cooling fluid supply source, such as a compressor (not shown), and pass the cooling fluids into one or more central cooling fluid collection chambers22to cool internal aspects of the turbine airfoil10. Passing the cooling fluids through the pressure and suction side outer wall chambers18,20first before passing the cooling fluids through other portions of the cooling system provides enhanced cooling capabilities to the turbine airfoil10and reduces stress inducing temperature gradients that exist at operating conditions between the outer wall14and internal aspects, such as internal ribs24, of the turbine airfoil10.

As shown inFIG. 1, the turbine vane10may be formed from a generally elongated hollow airfoil having an outer surface28adapted for use, for example, in an axial flow turbine engine. Outer surface28may have a generally concave shaped portion forming pressure side30and a generally convex shaped portion forming suction side31, as shown inFIG. 2. The turbine vane10may also include an outer endwall32adapted to be coupled to a hook attachment34at a first end33and may include a second end36adapted to be coupled to an inner endwall38. The airfoil22may also include a leading edge40and a trailing edge42.

As shown inFIGS. 2 and 3, the cooling system12may be formed from at least one suction side outer wall chamber20positioned in the outer wall14of the airfoil and extending from proximate the first endwall32of the generally elongated hollow airfoil toward the second end34. In at least one embodiment, as shown inFIG. 2, the suction side outer wall chamber20may be formed from a forward suction side outer wall chamber44positioned proximate to the leading edge40of the elongated hollow airfoil26, an aft suction side outer wall chamber48positioned proximate to the trailing edge42, and a mid suction side outer wall chamber46positioned between the forward and aft pressure side outer wall chambers44,48. One or more of the forward, mid, and aft suction side outer wall chambers44,46,48may be in communication with a suction side inlet opening49in an OD endwall32of the turbine airfoil10at the first end33of the generally elongated hollow airfoil26. The suction side inlet opening may establish a cooling fluid channel between an OD cooling fluid supply, such as a compressor (not shown) and the forward, mid, and aft pressure side outer wall chambers44,46,48. In at least one embodiment, the suction side outer wall chambers44,46,48may extend from the endwall32at the first end33to the inner endwall38at the second end36, as shown inFIG. 2.

The suction side outer wall chambers20may be in fluid communication with the central cooling fluids collection chambers22through one or more suction side cooling fluid turns52that coupling the suction side outer wall chambers20to the central cooling fluid collection chamber22. The suction side cooling fluid turn52may be positioned between the first end33and the second end36. In at least one embodiment, the suction side cooling fluid turn52may be positioned in close proximity to the inner endwall38, as shown inFIG. 3, such that the inner endwall38forms a portion of the suction side cooling fluid turn52. One or more suction side cooling fluid turns52may be used to couple the suction side outer wall chambers18to the central cooling fluid collection chamber22. In at least one embodiment, the suction side cooling fluid turn52may be formed from a forward, mid, and aft suction side cooling fluid turn. The forward, mid, and aft suction side cooling fluid turns may be in fluid communication with the corresponding forward, mid, and aft suction side outer wall chambers44,46,48.

As shown inFIGS. 2 and 3, the cooling system12may be formed from at least one pressure side outer wall chamber18positioned in the outer wall14of the airfoil and extending from proximate the first endwall32of the generally elongated hollow airfoil toward the second end34. In at least one embodiment, as shown inFIG. 2, the pressure side outer wall chamber18may be formed from a forward pressure side outer wall chamber60positioned proximate to the leading edge40of the elongated hollow airfoil26and an aft pressure side outer wall chamber62positioned proximate to the trailing edge42. One or both of the forward and aft pressure side outer wall chambers60,62may be in communication with a pressure side inlet opening in an OD endwall32of the turbine airfoil10at the first end33of the generally elongated hollow airfoil26. The pressure side inlet opening may establish a cooling fluid channel between an OD cooling fluid supply, such as a compressor (not shown) and the forward and aft pressure side outer wall chambers60,62. In at least one embodiment, the pressure side outer wall chambers60,62may extend from the endwall32at the first end33to the inner endwall38at the second end36, as shown inFIG. 2.

The pressure side outer wall chambers18may be in fluid communication with the central cooling fluids collection chambers22through one or more pressure side cooling fluid turns66that couple the pressure side outer wall chambers18to the central cooling fluid collection chamber22. The pressure side cooling fluid turn66may be positioned between the first end33and the second end36of the elongated hollow airfoil26. In at least one embodiment, the pressure side cooling fluid turn66may be positioned in close proximity to the inner endwall38, as shown inFIG. 3, , such that the inner endwall38forms a portion of the pressure side cooling fluid turn66. One or more pressure side cooling fluid turns66may be used to couple the pressure side outer wall chambers18to the central cooling fluid collection chamber22. In at least one embodiment, the pressure side cooling fluid turn66may be formed from a forward and aft pressure side cooling fluid turn. The forward and aft pressure side cooling fluid turns may be in fluid communication with the corresponding forward and aft pressure side outer wall chambers60,62.

As shown inFIGS. 2 and 3, and in detail inFIG. 4, the pressure and suction side outer wall chambers18,20include one or more ribs having one or more impingement orifices for increasing the heat transfer between the cooling fluids passing through the cooling system12and the turbine airfoil10. As shown inFIG. 4, the suction side outer wall chamber20includes a first rib72including a plurality of impingement orifices74and includes a second rib76including a plurality of impingement orifices78positioned downstream from the first rib72. The plurality of impingement orifices74in the first rib72may be offset in a general chordwise direction relative to the plurality of impingement orifices78in the second rib76. The offset pattern between the impingement orifices74,78of the first and second ribs72,76forms a repeating pattern that may be positioned in portions of or entirely between the first end33and the second end36. The repeating pattern of offset impingement orifices74,78may be positioned in the forward, mid, and aft suction side outer wall chambers44,46,48. One or more of the impingement orifices74,78may include a bell-shaped mouth80, as shown inFIG. 4, to decrease head loss of cooling fluids flowing through the impingement orifices74,78. The ribs72,76may be extend generally spanwise and be positioned orthogonal to cooling fluid flow. In other embodiments, the ribs72,76may be positioned at other angles relative to fluid flow.

As shown inFIG. 5, the pressure side outer wall chamber18includes a first rib82including a plurality of impingement orifices84and includes a second rib86including a plurality of impingement orifices88positioned downstream from the first rib82. The plurality of impingement orifices84in the first rib82may be offset in a general chordwise direction relative to the plurality of impingement orifices88in the second rib86. The offset pattern between the impingement orifices84,88of the first and second ribs82,86forms a repeating pattern that may be positioned in portions of or entirely between the first end33and the second end36. The repeating pattern of offset impingement orifices84,88may be positioned in the forward and aft pressure side outer wall chambers60,62. One or more of the impingement orifices84,88may include a bell-shaped mouth90, as shown in FIG.5, to decrease head loss of cooling fluids flowing through the impingement orifices84,88. The ribs82,86may be extend generally spanwise and be positioned orthogonal to cooling fluid flow. In other embodiments, the ribs82,86may be positioned at other angles relative to fluid flow.

As shown inFIG. 2, the central cooling fluid collection chamber22may be formed from a plurality of chambers. In particular, the central cooling fluid collection chamber22may be formed from a forward central cooling fluid collection chamber92, an aft central cooling fluid collection chamber96, and a mid central cooling fluid collection chamber94positioned between the forward and aft central cooling fluid collection chambers92,96. The forward, mid, and aft central cooling fluid collection chambers92,94,96may be in fluid communication with the pressure and suction side outer wall chambers18,20. In particular, the forward central cooling fluid collection chamber92may be in fluid communication with the forward suction side outer wall chamber44and the forward pressure side outer wall chamber60. The mid central cooling fluid collection chamber94may be in fluid communication with the mid suction side outer wall chamber46and the forward pressure side outer wall chamber60. The aft central cooling fluid collection chamber94may be in fluid communication with the aft suction side outer wall chamber48and the aft pressure side outer wall chamber62. Thus, the central cooling fluid collection chambers22may receive cooling fluids from the pressure or suction side outer wall chambers18,20.

The central cooling fluid collection chambers22may exhaust cooling fluids through numerous channels. As shown inFIG. 2, the cooling fluid collection chamber22, and specifically, the forward cooling fluid collection chamber92, may be in communication with a leading edge impingement chamber98through one or more impingement orifices100. The leading edge impingement chamber98may include a plurality of film cooling holes102extending through the outer wall14forming a showerhead. A pressure side film cooling hole104and a suction side film cooling hole106may be positioned in the outer wall14as well and be in fluid communication with the leading edge impingement chamber98. The leading edge impingement chamber98may extend from the first end33to the second edge36of the elongated hollow airfoil26or may have a shorter length.

As shown inFIG. 2, the cooling fluid collection chamber22, and specifically, the aft cooling fluid collection chamber92, may be in communication with a trailing edge impingement chamber108through one or more impingement orifices110. The trailing edge impingement chamber108may include a plurality of trailing edge exhaust orifices112extending through the outer wall14of the trailing edge42. The trailing edge impingement chamber108may extend from the first end33to the second end36of the elongated hollow airfoil26or may have a shorter length.

The central cooling fluid collection chambers22may also exhaust cooling fluids through one or more film cooling holes114. In particular, the forward central cooling fluid collection chamber92may exhaust cooling fluids through one or more film cooling holes114on the suction side31. The mid central cooling fluid collection chambers94may exhaust cooling fluids through one or more film cooling holes114on the suction side31, the pressure side30, or both. The aft central cooling fluid collection chambers96may exhaust cooling fluids through one or more film cooling holes114on the pressure side30.

During operation, the cooling fluids flow from a cooling fluid supply source (not shown) through the endwall32at the OD of the turbine airfoil10. The cooling fluids flow into the pressure and suction side outer wall chambers18,20. The cooling fluids increase in temperature upon receiving heat from the turbine airfoil26as the cooling fluids flow through the impingement orifices74,78,84,88of the suction and pressure side outer wall chambers20,18. In particular, as cooling fluids flow through the impingement orifices74, the cooling fluids impinge on the rib76and cool the rib76. Similarly, as cooling fluids flow through the impingement orifices84, the cooling fluids impinge on the rib86and cool the rib86. The cooling fluids may also flow through impingement orifices78or88and impinge on ribs72or82, respectively. The cooling fluids also spread out through the impingement cavities formed by the ribs72,76,82,86in the suction and pressure side outer wall chambers20,18and contact and cool the walls forming these components of the airfoil10. This cooling mechanism is repeated throughout the pressure and suction side outer wall chambers18,20. The cooling fluids then flow through the pressure or suction side cooling fluid turns66,52and into the central cooling fluid collection chamber22. Cooling fluids flow into the forward, mid, and aft central cooling fluid collection chambers92,94,96. The cooling fluids entering the forward, mid, and aft central cooling fluid collection chambers92,94,96have been heated while passing through the pressure and suction side outer wall chambers18,20. As a result, a smaller temperature gradient is established between the ribs24forming the forward, mid, and aft central cooling fluid collection chambers92,94,96and the outer wall14than in conventional airfoils.

The cooling fluids may be expelled out of the central cooling fluid collection chamber22and into the leading edge impingement chamber98, the trailing edge impingement chamber108, and the film cooling holes114. In particular, cooling fluids may pass from the forward central cooling fluid chamber92and into the leading edge impingement chamber98through impingement orifices100. The cooling fluids may be exhausted from the leading edge impingement chamber98through the plurality of film cooling holes102extending through the outer wall14forming a showerhead, the pressure side film cooling hole104, and the suction side film cooling hole106. The cooling fluids may pass from the forward central cooling fluid chamber92and into the trailing edge impingement chamber108through one or more impingement orifices110. The cooling fluids may be exhausted from the trailing edge impingement chamber108through exhaust orifices112extending through the outer wall14of the trailing edge42. The central cooling fluid collection chambers22may also exhaust cooling fluids through the film cooling holes114. In particular, the forward central cooling fluid collection chamber92may exhaust cooling fluids through one or more film cooling holes114on the suction side31. The mid central cooling fluid collection chambers94may exhaust cooling fluids through one or more film cooling holes114on the suction side31, the pressure side30, or both. The aft central cooling fluid collection chambers96may exhaust cooling fluids through one or more film cooling holes114on the pressure side30.