TO SUPPLY TURBINE AIRFOILS

FIELD OF THE INVENTION

This invention is directed generally to turbine engines, and more particularly to cooling fluid feed systems in turbine engines.

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

Typically, turbine vanes extend radially inward from a vane carrier and

terminate within close proximity of a rotor assembly. The turbine vanes typically include a plurality of cooling channels positioned in internal aspects of the turbine vanes. Cooling fluid is often supplied to the row 1 turbine blade assembly via axially aligned holes in a rotor seal disk, as shown in Figure 2. The holes in the seal disk are parallel with the longitudinal axis of the rotor seal disk. The cooling fluid can enter the axial holes in the rotor seal disk at an over swirl condition and are

exhausted from outlets in the axial holes with a swirl ratio of 1 , whereby a rotational velocity of the cooling fluid equals a rotational velocity of the outlets of the axial holes. In the over swirl condition, the rotational velocity of the cooling fluid is greater than a rotational velocity of the inlets of the axial holes. After the cooling fluid has passed through the axial holes in the rotor seal disk, the cooling fluid is pumped radially outward. Without additional manipulation, as the cooling fluid is moved radially outward, the rotational velocity of the cooling fluid decreases. Pumping fins on the upstream surface of the row 1 turbine disk, as shown in Figures 2-4, have been used to counteract this loss in rotational velocity of the cooling fluid. In particular, as shown in Figures 3 and 4, after the cooling fluid has passed through the axial holes in the rotor seal disk, the cooling fluid is pumped radially outward to the row 1 turbine blade assembly via a plurality of pumping fins on the turbine disk. The cooling fluid at the radially outer position, radially outward of the pumping fins at an entrance to a cooling system within a turbine airfoil, may have a swirl ratio of about 1 due to the pumping fins. The pumping fins on the turbine disk are useful to avoid swirl ratio drop normally associated with free vortex flow radially outward. Nonetheless, the pumping fins on the turbine disk or the cover plate add complexity to the engine and increased costs. Thus, a need exists for a more cost effective system configured to realize efficiencies of supplying cooling fluid to turbine blade cooling systems with a swirl ratio of about 1 .

SUMMARY OF THE INVENTION

A cooling fluid feed system for a turbine engine for directing cooling fluids from a compressor to turbine airfoils with improved swirl of the cooling fluid flow, thereby enhancing efficiency, is disclosed. In at least one embodiment, the cooling fluid feed system for a turbine engine may direct cooling fluids from a compressor, past pre-swirl vanes and through one or more fluid supply channels positioned within a rotatable body and positioned nonparallel and nonorthogonal with a longitudinal axis of the at least one rotatable body, when viewed radially inwardly, such that the cooling fluid exhausted from the rotatable body experiences less rotational velocity loss than conventional cooling systems. In at least one embodiment, the cooling fluid feed system may receive cooling fluid at an overswirl rotational speed and may exhaust the cooling fluid in an overswirl condition, thereby eliminating a need and costs for pumping fins on a turbine disk.

In at least one embodiment, the turbine engine may be formed from one or more combustors positioned upstream from a rotor assembly, wherein the rotor assembly includes at least first and second rows of turbine blades extending radially outward from a rotor. The turbine engine may also include a compressor positioned upstream from the at least one combustor and a first row of turbine vanes attached to a vane carrier, whereby the turbine vanes may each extend radially inward and terminate proximate to the rotor assembly upstream of the first row of turbine blades. The turbine engine may include one or more rows of pre-swirl vanes extending radially outward and collected together to form a ring of radially outward extending pre-swirl vanes, whereby the pre-swirl vanes are nonrotatable during turbine engine operation. The turbine engine may include one or more rotatable bodies positioned downstream from the row of pre-swirl vanes and positioned to receive cooling fluid from the rotatable body. The rotatable body may be configured to rotate about a longitudinal axis of the turbine engine and may include one or more fluid supply channels extending axially therethrough. The fluid supply channel may be positioned nonparallel and nonorthogonal with a longitudinal axis of the rotatable body, when viewed radially inwardly. In at least one embodiment, the rotatable body may be formed from one or more rotor seal disks.

In at least one embodiment, the fluid supply channel may include a plurality of fluid supply channels positioned nonparallel and nonorthogonal with a longitudinal axis of the rotatable body, when viewed radially inwardly. In at least one

embodiment, a longitudinal axis of the fluid supply channel may be offset angularly from the longitudinal axis of the rotatable body by between about 10 degrees and about 40 degrees. In another embodiment, the longitudinal axis of the fluid supply channel may be offset angularly from the longitudinal axis of the rotatable body by between about 20 degrees and about 30 degrees. The fluid supply channel may include an inlet with a tapered transition section. The fluid supply channel may include an outlet with a tapered diffusion section. The outlet of the fluid supply channel may be tapered along a downstream edge. The fluid supply channel may have a length that is greater than a width of the at least one fluid supply channel. The fluid supply channel may have a length that is at least three times greater than a width of the at least one fluid supply channel. In at least one embodiment, the fluid supply channel may be, but is not limited to being, cylindrical.

An advantage of the cooling fluid feed system is that cooling fluid feed system emits cooling fluid from an outlet in an overswirl condition thereby enabling the cooling fluid to exist in a swirl condition at an entrance to a turbine airfoil cooling system positioned radially further outward than the outlet of the cooling fluid feed system, whereby the swirl condition is one in which the rotational velocity of the cooling fluid is equal to the rotational velocity of the entrance to the turbine airfoil cooling system.

Another advantage of the cooling fluid feed system is that conventional pumping fins positioned on the turbine disk between the rotor seal disk and turbine airfoil cooling system are no longer needed, thereby reducing design complexity and saving costs.

Yet another advantage of the cooling fluid feed system is that the angled fluid supply channels in the rotor seal disk function to preserve an over swirled condition in which the cooling fluid is supplied to the angled fluid supply channels, thereby enhancing the efficiency of the system.

Another advantage of the cooling fluid feed system is that the angle of the fluid supply channels in the rotor seal disk may be customized, such that the angle is increased or decreased, so as to achieve a swirl ratio of one when the cooling fluid enters the blade supply cavity.

Still another advantage of the cooling fluid feed system is that the angled fluid supply channels may include a diffuser section configured to pressure recovery of the cooling fluid exiting the angled fluid supply channels.

These and other embodiments are described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

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.

Figure 1 is a cross-sectional side view of a turbine engine including a cooling fluid feed system for supplying cooling fluid to a row 1 turbine airfoil assembly.

Figure 2 is a detailed view of a portion of a prior art turbine engine shown, by way of location, in Figure 1 at detail 2.

Figure 3 is a detailed view of a portion of the prior art turbine engine shown in Figure 2 at detail 3.

Figure 4 is a perspective view of the prior art turbine disk shown in Figure 3 at detail 4. Figure 5 is a detailed view of a portion of the turbine engine shown in Figure 1 at detail 2 together with the cooling fluid feed system for supplying cooling fluid to a row 1 turbine airfoil assembly.

Figure 6 is a cross-sectional view of the pre-swirl blades and the fluid supply channels 20 in the rotatable body 22 taken along section line 6-6 in Figure 5.

Figure 7 is a cross-sectional view of the pre-swirl blades and the fluid supply channels 20 in the rotatable body 22 taken along section line 7-7 in Figure 5.

DETAILED DESCRIPTION OF THE INVENTION

As shown in Figures 1 and 5-7, a cooling fluid feed system 10 for a turbine engine 12 for directing cooling fluids from a compressor 14 to turbine airfoils 16 with improved swirl of the cooling fluid flow, thereby enhancing efficiency, is disclosed. In at least one embodiment, the cooling fluid feed system 10 for a turbine engine 12 may direct cooling fluids from a compressor 14, past pre-swirl vanes 18 and through one or more fluid supply channels 20 positioned within a rotatable body 22 and positioned nonparallel and nonorthogonal with a longitudinal axis 24 of the rotatable body 22, when viewed radially inwardly, such that the cooling fluid exhausted from the rotatable body 22 experiences less rotational velocity loss than conventional cooling systems. In at least one embodiment, the cooling fluid feed system 10 may receive cooling fluid at an overswirl rotational speed and may exhaust the cooling fluid in an overswirl condition, thereby eliminating a need and costs for pumping fins on a turbine disk 26.

In at least one embodiment, as shown in Figure 1 , a turbine engine 12 may include one or more combustors 28 positioned upstream from a rotor assembly 30. The rotor assembly 30, as shown in Figure 5, may include at least first and second rows 32, 34 of turbine blades 46 extending radially outward from a rotor 36. The turbine engine 12 may include one or more compressors 14 positioned upstream from the combustor 28. The turbine engine 12 may include a first row 38 of turbine vanes 40 attached to a vane carrier 42. The turbine vanes 40 may each extend radially inward and terminate proximate to the rotor assembly 30 upstream of a first row 32 of turbine blades 46. The turbine engine 12 may include one or more pre- swirl vanes 1 8 extending radially outward and collected together to form a ring of radially outward extending pre-swirl vanes 18. The pre-swirl vanes 18 may be nonrotatable during turbine engine operation.

The turbine engine 12 may include one or more rotatable bodies 22 positioned downstream from the row of pre-swirl vanes 18 and positioned to receive cooling fluid from the pre-swirl vanes 18. The rotatable body 22 may be configured to rotate about a longitudinal axis 48 of the turbine engine 12 and may include one or more fluid supply channels 20 extending axially therethrough. The fluid supply channel 20 may be positioned nonparallel and nonorthogonal with the longitudinal axis 24 of the rotatable body 24, when viewed radially inwardly. In at least one embodiment, the rotatable body 22 may be formed from one or more rotor seal disks 50. The rotor seal disk 50 may be positioned radially inward from the first row 38 of turbine vanes 40.

In at least one embodiment, as shown in Figures 6 and 7, the fluid supply channel 20 may be formed from a plurality of fluid supply channels 20 positioned nonparallel and nonorthogonal with the longitudinal axis 24 of the rotatable body 22, when viewed radially inwardly. A longitudinal axis 52 of the fluid supply channel 20 may be offset angularly from the longitudinal axis 24 of the rotatable body 22. In at least one embodiment, the longitudinal axis 52 of the fluid supply channel 20 may be offset angularly from the longitudinal axis 24 of the rotatable body 22 by between about 10 degrees and about 40 degrees. In yet another embodiment, the

longitudinal axis 52 of the fluid supply channel 20 may be offset angularly from the longitudinal axis 24 of the rotatable body 22 by between about 20 degrees and about 30 degrees.

The fluid supply channel 20 may have any appropriate configuration for maintaining an overswirl condition as the cooling fluid is exhausted from the fluid supply channel 20. In at least one embodiment, the fluid supply channel 20 may have a length that is greater than a width of the fluid supply channel 20. The fluid supply channel 20 may have a length that is at least three times greater than a width of the supply channel 20. The fluid supply channel 20 may be, but is not limited to being, cylindrical.

As shown in Figures 6 and 7, the fluid supply channel 20 may include an inlet 54 with a tapered transition section 56. The inlet 54 may or may not include the tapered transition section 56. The fluid supply channel 20 may include an outlet 58 with a tapered diffusion section 60, as shown in Figure 7. The tapered diffusion section 60 is a flow diffusion feature for pressure recovery of the flow exiting the angled fluid supply channels 20. The outlet 58 of the fluid supply channel 20 may be tapered along a downstream edge 62. In at least one embodiment, the fluid supply channel 20 may be tapered only along the downstream edge 62, as shown in Figure 7.

During use, cooling fluid is provided from the compressor 14 to the pre-swirl vanes 18. The pre-swirl vanes 18 impart an angled direction of flow with a tangential vector, which is orthogonal to the longitudinal axis 48 of the turbine engine 12, to the cooling fluid as the cooling fluid is exhausted from the pre-swirl vanes 18. The cooling fluid is exhausted from the pre-swirl vanes 18 in an overswirl condition in which the swirl ratio is greater than 1 . An overswirl condition occurs where the cooling fluid has a larger circumferential speed than the rotational speed of the rotor 36. The cooling fluid then flows into the one or more angled fluid supply channels 20 through the inlet 54 and into the fluid supply channels 20. The cooling fluid may then be exhausted through the tapered diffuser section 60 into a cavity formed in part by an upstream surface of the row 1 turbine disk 26 and then into a cooling system for the turbine airfoils 16. The swirl ratio of the cooling fluid at the outlet 58 of the fluid supply channel 20 is greater than 1 , and thus an overswirl condition. The swirl ratio at the outlet of the cavity formed in part by an upstream surface of the row 1 turbine disk 26 is about 1 . The swirl ratio decreases as the cooling fluid moves radially outward. Thus, the cooling fluid feed system 10 may be configured such that the cooling fluid in the fluid supply channels 20 is overswirled at such a speed that after being exhausted from the fluid supply channels 20 and traveling to an inlet 64 of the cooling system 66 for the turbine airfoils 16, the cooling fluid has a swirl ratio of 1 , whereby the rotational speed of the cooling fluid is equal to a rotational speed of the inlet 64 of the cooling system 66 for the turbine airfoils 16.

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.